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Dichotomous keys to the species of Solanum L. (Solanaceae) in continental Africa, Madagascar (incl. the Indian Ocean islands), Macaronesia and the Cape Verde Islands
expand article infoSandra Knapp, Maria S. Vorontsova§, Tiina Särkinen|
‡ Natural History Museum, London, United Kingdom
§ Royal Botanic Gardens, Kew, United Kingdom
| Royal Botanic Garden, Edinburgh, United Kingdom
Open Access

Abstract

Solanum L. (Solanaceae) is one of the largest genera of angiosperms and presents difficulties in identification due to lack of regional keys to all groups. Here we provide keys to all 135 species of Solanum native and naturalised in Africa (as defined by World Geographical Scheme for Recording Plant Distributions): continental Africa, Madagascar (incl. the Indian Ocean islands of Mauritius, La Réunion, the Comoros and the Seychelles), Macaronesia and the Cape Verde Islands. Some of these have previously been published in the context of monographic works, but here we include all taxa. The paper is designed to be used in conjunction with the web resource Solanaceae Source (www.solanaceaesource.org) and hyperlinks provide access to online descriptions, synonymy and images (where available) of each species. All taxa treated and specimens seen are included in searchable Suppl. material 1, 2.

Keywords

Africa, Aldabra, Azores, Canary Islands, Cape Verde, Comoros, cultivated plants, identification, keys, Madagascar, Madeira, Mauritius, La Réunion, Seychelles, Solanum, weeds

Introduction

Solanum L. (Solanaceae) is one of the largest of angiosperm genera (Frodin 2004) with ca. 1,200 species distributed worldwide with species on all continents except Antarctica. The greatest species diversity in the genus occurs in the Neotropics (see Bohs 2005), but significant diversity also occurs in the Old World, with Africa and Australia particularly important areas for diversification (see Vorontsova and Knapp 2016; Echeverría-Londoño et al. 2018). Due to its large number of species and the number of introductions and cultivated taxa, Solanum is often an identification challenge for non-specialists. Recent completion of several large monographic treatments of the Solanum of Africa (e.g. Vorontsova and Knapp 2016; Knapp and Vorontsova 2016; Särkinen et al. 2018) as part of the US National Science Foundation funded Planetary Biodiversity Inventory project “PBI Solanum” means we can now provide keys for the genus across the continent and for adjacent islands such as Madagascar and Macaronesia. Some of these have been published in the Open Access literature (e.g. Knapp 2013; Knapp and Vorontsova 2016; Särkinen et al. 2018), but the largest of these, treating the spiny solanums (Vorontsova and Knapp 2016) is not. Several species that are either naturalised (e.g. members of the Brevantherum Clade) or cultivated (tree tomatoes, pepinos, potatoes and tomatoes) in the region are also not treated as part of these monographic treatments, although complete species descriptions and photographs are provided on the web resource Solanaceae Source (www.solanaceaesource.org).

Here we provide dichotomous keys that include all groups and species (native, naturalised and widely cultivated; see Table 1 for species list) of Solanum occurring in continental Africa, Madagascar (incl. the Indian Ocean islands of Mauritius, La Réunion, the Comoros, and the Seychelles), Macaronesia and the Cape Verde Islands to facilitate identification across the region. Taxa occurring in each country in the region are shown in Table 2 and a map of Solanum diversity (all taxa) is presented in Figure 1. Keys to individual groups are also provided for the 135 Solanum species occurring in the region (see Table 1 and Appendix 1 for a species list). We hope that these keys will encourage collection and documentation of Solanum across Africa and uncover new distributions and perhaps new species for the region.

The 135 species of Solanum (native, naturalised and widely cultivated) occurring in Africa as defined by Brummitt (2001), with their places of original publication and clade membership as currently understood (Major Clades sensu Bohs 2005; minor clades are divisions within these sensu Bohs 2007; Stern et al. 2011; Vorontsova et al. 2103; Särkinen et al. 2015, 2018; Aubriot et al. 2016; Tepe et al. 2016).

Species Place of original publication Major Clade Minor clade
Solanum aculeastrum Dunal Prodr. [A. P. de Candolle] 13(1): 366. 1852. Leptostemonum Old World-Africa
Solanum aculeatissimum Jacq. Collectanea [Jacquin] 1: 100. 1787 [‘1786’]. Leptostemonum Acanthophora
Solanum adoense Hochst. ex A.Rich. Tent. Fl. Abyss. 2: 105. 1850 [1851]. Leptostemonum Old World-Africa
Solanum aethiopicum L. Cent. Pl. 2: 10. 1756. Leptostemonum Old World-Africa
Solanum africanum Mill. Gard. Dict. ed. 8, no. 26. 1768. African non-spiny (ANS)
Solanum agnewiorum Voronts. Phytotaxa 10: 32. 2010. Leptostemonum Old World-Africa
Solanum agrarium Sendtn. Fl. Bras. (Martius) 10: 68, fig. 5, 32–33. 1846. Leptostemonum Gardneri
Solanum aldabrense C.H.Wright Kew Bull. 1894: 149. 1894. Leptostemonum Old World
Solanum americanum Mill. Gard. Dict. ed. 8, no. 5. 1768. Morelloid Black nightshade
Solanum anguivi Lam. Tabl. Encycl. 2: 23. 1794. Leptostemonum Old World-Africa
Solanum anomalum Thonn. Beskr. Guin. Pl. 126 1827. Leptostemonum Old World-Africa
Solanum arundo Mattei Boll. Reale Orto Bot. Giardino Colon. Palermo 7: 188. 1908. Leptostemonum Old World-Africa
Solanum atropurpureum Schrank Syll. Ratisb. 1: 200. 1824. Leptostemonum Acanthophora
Solanum aureitomentosum Bitter Repert. Spec. Nov. Regni Veg. 11: 18. 1912. Leptostemonum Old World-Africa
Solanum batoides D’Arcy & Rakot. Fl. Madag., Fam. 176: 75. 1994. Leptostemonum Old World-Madagascar
Solanum betaceum Cav. Anales Hist. Nat. 1: 44. 1799. Cyphomandra Pachyphylla
Solanum betroka D’Arcy & Rakot. Fl. Madag., Fam. 176: 77. 1994. African non-spiny (ANS)
Solanum bumeliifolium Dunal Prodr. [A. P. de Candolle] 13(1): 292. 1852. Leptostemonum Old World-Madagascar
Solanum burchellii Dunal Prodr. [A. P. de Candolle] 13(1): 291. 1852. Leptostemonum Old World-Africa
Solanum campylacanthum Hochst. ex A.Rich. Tent. Fl. Abyss. 2: 102. 1850. Leptostemonum Old World-Africa
Solanum capense L. Syst. ed. 10: 935. 1759. Leptostemonum Old World-Africa
Solanum capsicoides All. Auct. Syn. Meth. Stirp. Hort. Regii Taur. 64. 1773. Leptostemonum Acanthophora
Solanum catombelense Peyr. Sitzungsber. Kaiserl. Akad. Wiss., Math.-Naturwiss. Cl. 38: 576. 1860. Leptostemonum Old World-Africa
Solanum cerasiferum Dunal Prodr. [A. P. de Candolle] 13(1): 365. 1852. Leptostemonum Old World-Africa
Solanum chenopodioides Lam. Tabl. Encycl. 2: 18. 1794. Morelloid Black nightshade
Solanum chrysotrichum Schltdl. Linnaea 19: 304. 1847. Leptostemonum Torva
Solanum coagulans Forssk. Fl. Aegypt.-Arab. 47. 1775. Leptostemonum Old World-Africa
Solanum cordatum Forssk. Fl. Aegypt.-Arab. 47. 1775. Leptostemonum [not assigned]
Solanum croatii D’Arcy & R.C.Keating Phytologia 34: 282. 1976. Leptostemonum Old World-Madagascar
Solanum cyaneopurpureum De Wild. Pl. Bequaert. 1: 425. 1922. Leptostemonum Old World-Africa
Solanum cymbalariifolium Chiov. Boll. Soc. Bot. Ital. 1925: 107. 1925. Leptostemonum Old World-Africa
Solanum dasyphyllum Schumach. & Thonn. Beskr. Guin. Pl. 126 [146]. 1827. Leptostemonum Old World-Africa
Solanum dennekense Dammer Bot. Jahrb. Syst. 38: 57. 1905. Leptostemonum Old World-Africa
Solanum diphyllum L. Sp. Pl. 184. 1753. Geminata
Solanum elaeagnifolium Cav. Icon. 3: 22, tab. 243. 1795. Leptostemonum Elaeagnifolium
Solanum erianthum D.Don Prodr. Fl. Nep. 96. 1825. Brevantherum
Solanum erythracanthum Dunal Prodr. [A. P. de Candolle] 13(1): 201. 1852. Leptostemonum Old World-Madagascar
Solanum forskalii Dunal Hist. Nat. Solanum 237. 1813. Leptostemonum Old World-Africa
Solanum giganteum Jacq. Collectanea [Jacquin] 4: 125. 1791. Leptostemonum Old World-Africa
Solanum glabratum Dunal Hist. Nat. Solanum 240. 1813. Leptostemonum Old World-Africa
Solanum goetzei Dammer Bot. Jahrb. Syst. 28: 473. 1900. Leptostemonum Old World-Africa
Solanum guineense L. Sp. Pl. 184. 1753. African non-spiny (ANS)
Solanum hastifolium Hochst. ex Dunal Prodr. [A. P. de Candolle] 13(1): 284. 1852. Leptostemonum Old World-Africa
Solanum heinianum D’Arcy & R.C.Keating Phytologia 34: 282. 1976. Leptostemonum Old World-Madagascar
Solanum herculeum Bohs Plant Syst. Evol. 228: 44. 2001. Normania
Solanum humblotii Dammer Bot. Jahrb. Syst. 38: 184. 1906. African non-spiny (ANS)
Solanum humile Lam. Tabl. Encycl. 2: 23. 1794. Leptostemonum Old World-Africa
Solanum imamense Dunal Prodr. [A. P. de Candolle] 13(1): 85. 1852. African non-spiny (ANS)
Solanum inaequiradians Werderm. Notizbl. Bot. Gart. Berlin-Dahlem 12: 90. 1934. Leptostemonum Old World-Africa
Solanum incanum L. Sp. Pl. 188. 1753. Leptostemonum Old World-Africa
Solanum insanum L. Mant. 1: 46. 1767. Leptostemonum Old World-Tropical Asia
Solanum ivohibe D’Arcy & Rakot. Fl. Madag., Fam. 176: 97. 1994. African non-spiny (ANS)
Solanum jubae Bitter Bot. Jahrb. Syst. 54: 501. 1917. Leptostemonum Old World-Africa
Solanum laciniatum Aiton Hort. Kew. ed. 1, 1: 247. 1789. Archaesolanum
Solanum lamprocarpum Bitter Repert. Spec. Nov. Regni Veg. Beih. 16: 107. 1923. Leptostemonum Old World-Africa
Solanum lanzae J.-P.Lebrun & Stork Candollea 50: 217. 1995. Leptostemonum Old World-Africa
Solanum lichtensteinii Willd. Enum. Pl. (Willdenow) 1: 238. 1809. Leptostemonum Old World-Africa
Solanum lidii Sunding Blyttia 24: 368. 1966. Leptostemonum Old World
Solanum linnaeanum Hepper & P.-M.L. Jaeger Kew Bull. 41: 435. 1986. Leptostemonum Old World-Africa
Solanum litoraneum A.E.Gonç. Kew Bull. 52(3): 703. 1997. Leptostemonum Old World-Africa
Solanum lycopersicum L. Sp. Pl. 185. 1753. Potato Tomato
Solanum macracanthum A.Rich. Tent. Fl. Abyss. 2: 106. 1850. Leptostemonum Old World-Africa
Solanum macrocarpon L. Mant. Pl. Altera: 205. 1771. Leptostemonum Old World-Africa
Solanum macrothyrsum Dammer Bot. Jahrb. Syst. 38: 185. 1906. African non-spiny (ANS)
Solanum madagascariense Dunal Prodr. [A. P. de Candolle] 13(1): 99. 1852. African non-spiny (ANS)
Solanum mahoriense D’Arcy & Rakot. Ann. Missouri Bot. Gard. 73: 498. 1986. Leptostemonum Old World-Madagascar
Solanum malindiense Voronts. Syst. Bot. 35: 904. 2010. Leptostemonum Old World-Africa
Solanum mammosum L. Sp. Pl. 187. 1753. Leptostemonum Acanthophora
Solanum marginatum L.f. Suppl. 147. 1781. Leptostemonum Old World-Africa
Solanum mauense Bitter Repert. Spec. Nov. Regni Veg. Beih. 16: 42. 1923. Leptostemonum Old World-Africa
Solanum mauritianum Scop. Delic. Fl. Faun. Insubr. 3: 16. 1788. Brevantherum
Solanum melastomoides C.H.Wright Bull. Misc. Inform. Kew 1894: 128. 1894. Leptostemonum Old World-Africa
Solanum melongena L. Sp. Pl. 186. 1753. Leptostemonum Old World-Tropical Asia
Solanum memphiticum J.F.Gmel. Syst. Nat., ed. 13[bis] 2(1): 385. 1791 Morelloid Black nightshade
Solanum muricatum Aiton Hort. Kew, ed. 1, 1: 250. 1789. Potato Basarthrum
Solanum myoxotrichum Baker J. Linn. Soc., Bot. 21: 426. 1885. Leptostemonum Old World-Madagascar
Solanum myrsinoides D’Arcy & Rakot. Fl. Madag., Fam. 176: 115. 1994. African non-spiny (ANS)
Solanum nava Webb & Berthel. Phyt. Canar. 2. 3(3): 123. 1845. Normania
Solanum nigriviolaceum Bitter Repert. Spec. Nov. Regni Veg. Beih. 16: 163. 1923. Leptostemonum Old World-Africa
Solanum nigrum L. Sp. Pl. 186. 1753. Morelloid Black nightshade
Solanum nitidibaccatum Bitter Repert. Spec. Nov. Regni Veg. 11: 208. 1912. Morelloid Black nightshade
Solanum pampaninii Chiov. Res. Sci. Somalia Ital. 1: 128. 1916. Leptostemonum Old World-Africa
Solanum pauperum C.H.Wright Bull. Misc. Inform. Kew 1894: 127. 1894. Leptostemonum Old World-Africa
Solanum pectinatum Dunal Prodr. [A. P. de Candolle] 13(1): 250. 1852. Leptostemonum Lasiocarpa
Solanum phoxocarpum Voronts. Syst. Bot. 35: 903. 2010. Leptostemonum Old World-Africa
Solanum pimpinellifolium L. Cent. Pl. 1: 8. 1755. Potato Tomato
Solanum polhillii Voronts. Syst. Bot. 35: 902. 2010. Leptostemonum Old World-Africa
Solanum pseudospinosum C.H.Wright Fl. Trop. Afr. [Oliver et al.] 4, 2: 220. 1906. Morelloid Black nightshade
Solanum pyracanthos Lam. Tabl. Encycl. 2: 21. 1794. Leptostemonum Old World-Madagascar
Solanum retroflexum Dunal Prodr. [A. P. de Candolle] 13(1): 50. 1852. Morelloid Black nightshade
Solanum richardii Dunal Encycl. [J. Lamarck & al.] Suppl. 3: 775. 1814. Leptostemonum Old World-Africa
Solanum rigidum Lam. Tabl. Encycl. 2: 23. 1794. Leptostemonum Old World-Africa
Solanum robustum H.L.Wendl. Flora 27: 784. 1844. Leptostemonum Erythrotrichum
Solanum rubetorum Dunal Prodr. [A. P. de Candolle] 13(1): 304. 1852. Leptostemonum Old World-Africa
Solanum runsoriense C.H.Wright Uganda Prot. (H.H.Johnston) 1: 326. 1902. African non-spiny (ANS)
Solanum ruvu Voronts. J. E. Afr. Nat. Hist. 99: 230. (2010) 2011. Leptostemonum Old World-Africa
Solanum sambiranense D’Arcy & Rakot. Fl. Madag., Fam. 176: 123. 1994. African non-spiny (ANS)
Solanum sarrachoides Sendtn. Fl. Bras. (Martius) 10: 18, tab. 1, fig. 1-8. 1846. Morelloid Black nightshade
Solanum scabrum Mill. Gard. Dict. ed. 8, no. 6. 1768. Morelloid Black nightshade
Solanum schimperianum Hochst. ex A.Rich. Tent. Fl. Abyss. 2: 98. 1850. Leptostemonum Old World-Africa
Solanum schliebenii Werderm. Notizbl. Bot. Gart. Berlin-Dahlem 12: 92. 1934. Leptostemonum Old World-Africa
Solanum schumannianum Dammer Pflanzenw. Ost-Afrikas C (Engler): 352. 1895. Leptostemonum Old World-Africa
Solanum setaceum Dammer Pflanzenw. Ost-Afrikas C (Engler): 33. 1895. Leptostemonum Old World-Africa
Solanum sisymbriifolium Lam. Tabl. Encycl. 2: 25. 1794. Leptostemonum Sisymbriifolium
Solanum sodomeodes Kuntze Revis. Gen. Pl. 3(3): 227. 1898. Leptostemonum Old World-Africa
Solanum somalense Franch. Sert. Somal. 47. 1882. Leptostemonum Old World-Africa
Solanum stipitatostellatum Dammer Abh. Königl. Akad. Wiss. Berlin 1894: 63. 1894. Leptostemonum Old World-Africa
Solanum supinum Dunal Prodr. [A. P. de Candolle] 13(1): 289. 1852. Leptostemonum Old World-Africa
Solanum taitense Vatke Linnaea 43: 327. 1882. Leptostemonum Old World-Africa
Solanum tarderemotum Bitter Repert. Spec. Nov. Regni Veg. 10: 547. 1912. Morelloid Black nightshade
Solanum terminale Forssk. Fl. Aegypt.-Arab. 45. 1775. African non-spiny (ANS)
Solanum tettense Klotzsch Naturw. Reise Mossambique (Peters) 1: 237. 1861. Leptostemonum Old World-Africa
Solanum thomsonii C.H.Wright Fl. Trop. Afr. [Oliver et al.] 4, 2: 217. 1906. Leptostemonum Old World-Africa
Solanum toliaraea D’Arcy & Rakot. Ann. Missouri Bot. Gard. 76: 351. 1989. Leptostemonum Old World-Madagascar
Solanum tomentosum L. Sp. Pl. 188. 1753. Leptostemonum Old World-Africa
Solanum torreanum A.E.Gonç. Kew Bull., 52(3): 706. 1997. Leptostemonum Old World-Africa
Solanum torvum Sw. Prodr. [O. P. Swartz] 47. 1788. Leptostemonum Torva
Solanum trichopetiolatum D’Arcy & Rakot. Fl. Madag., Fam. 176: 130. 1994. African non-spiny (ANS)
Solanum triflorum Nutt. Gen. N. Amer. Pl. 1: 128. 1818. Morelloid
Solanum trisectum Dunal Prodr. [A. P. de Candolle] 13(1): 36. 1852. Normania
Solanum truncicola Bitter Bot. Jahrb. Syst. 54: 435. 1917. African non-spiny (ANS)
Solanum tuberosum L. Sp. Pl. 185. 1753. Potato Petota
Solanum umalilaense Manoko PhytoKeys 16: 67. 2012. Morelloid Black nightshade
Solanum umtuma Voronts. & S.Knapp PhytoKeys 8: 4. 2012. Leptostemonum Old World-Africa
Solanum usambarense Bitter & Dammer Repert. Spec. Nov. Regni Veg. Beih. 16: 40. 1923. Leptostemonum Old World-Africa
Solanum usaramense Dammer Pflanzenw. Ost-Afrikas C (Engler): 353. 1895. Leptostemonum Old World-Africa
Solanum vespertilio Aiton Hort. Kew. ed. 1, 1: 252. 1789. Leptostemonum Old World
Solanum viarum Dunal Prodr. [A. P. de Candolle] 13(1): 240. 1852. Leptostemonum Acanthophora
Solanum villosum Mill. Gard. Dict. ed. 8, no. 2. 1768. Morelloid Black nightshade
Solanum violaceum Ortega Nov. Pl. Descr. Dec. 56. 1798. Leptostemonum Old World-Tropical Asia
Solanum virginianum L. Sp. Pl. 187. 1753. Leptostemonum Old World-Tropical Asia
Solanum wendlandii Hook.f. Bot. Mag. 113: tab. 6914. 1887. Wendlandii-Allophyllum
Solanum wittei Robyns Bull. Jard. Bot. État Bruxelles 17: 82. 1943. Leptostemonum Old World-Africa
Solanum wrightii Benth. Fl. Hongk. 243. 1861. Leptostemonum Androceras-Crinitum
Solanum zanzibarense Vatke Linnaea 43: 326. 1882. Leptostemonum Old World-Africa

Country distribution of Solanum species in Africa (as defined here); introduced (incl. cultivated) species in brackets (epithet); taxa not included in the keys because they are known from a singleton cultivated specimen, are in italic type. All records based on specimens examined by the authors with verified identities. The status of S. torvum is not completely clear, but it is most likely to be introduced from the New World, so is treated as that here; S. americanum, on the other hand, appears to have a worldwide distribution, so is treated as native. The occurrence of S. rigidum in Senegal is doubtful, the specimen is very old and the label may be in error. Cultivated plants are often not collected, so the absence of records of commonly cultivated crops (e.g. S. lycopersicum, S. macrocarpon, S. tuberosum) should not be interpreted as lack of occurrence, merely as lack of collections. Solanum diphyllum was recorded from Eygpt by Fawzi and Habeeb (2016) with a verifiable photograph; this Mexican species is widely cultivated and easily naturalised and is likely to be spreading around the Mediterranean.

Country Species
Algeria herculeum, linnaeanum, nigrum, villosum
Angola aculeastrum. (aculeatissimum), aethiopicum, americanum, anguivi, anomalum, aureitomentosum, (betaceum), campylacanthum, capsicoides, catombelense, dasyphyllum, humile, lichtensteinii, (lycopersicum), macrocarpon, mammosum, (mauritianum), pauperum, scabrum, tarderemotum, terminale, tettense, villosum
Azores (linnaeanum), (chenopodioides), (chrysotrichum), (nava?), nigrum, (maritianum), (pseudocapsicum), villosum
Benin anguivi, anomalum, incanum, scabrum, (torvum)
Botswana campylacanthum, catombelense, lichtensteinii, retroflexum, scabrum, supinum, tarderemotum, tettense, villosum
Burkina Faso cerasiferum, dasyphyllum, incanum, scabrum
Burundi aculeastrum, anguivi, campylacanthum, cyaneopurpureum, dasyphyllum, mammosum, memphiticum, tarderemotum, terminale, villosum
Cabo Verde (agrarium), americanum, (lycopersicum), nigrum, rigidum, scabrum, tarderemotum, (torvum)
Cameroon aculeastrum, (aculeatissimum), aethiopicum, americanum, anguivi, anomalum, cerasiferum, dasyphyllum, (erianthum), giganteum, (lycopersicum), macrocarpon, (mauritianum), (melongena), pseudospinosum, scabrum, tarderemotum, terminale, (torvum), (wendlandii), (wrightii)
Canary Islands (Spain) americanum, (laxum), (lycopersicum), (mauritianum), nava, nigrum, (pseudocapsicum), (robustum), vespertilio, (wendlandii)
Central African Republic (CAR) aculeastrum, (aculeatissimum), anguivi, cerasiferum, dasyphyllum, giganteum, (lycopersicum), macrocarpon, scabrum, (seaforthianum), terminale, (torvum), (wrightii)
Chad cerasiferum, forskalii, incanum, tarderemotum, villosum
Comoros (incl. Mayotte) americanum, macrothyrsum, richardii, scabrum, tarderemotum, terminale, (torvum)
Democratic Republic of the Congo aculeastrum, (aculeatissimum), aethiopicum, anomalum, aureitomentosum, campylacanthum, cerasiferum, (chrysotrichum), cyaneopurpureum, dasyphyllum, giganteum, lichtensteinii, (lycopersicum), macrocarpon, (mammosum), (mauritianum), (melongena), memphiticum, richardii, runsoriense, scabrum, (seaforthianum), tarderemotum, terminale, tettense, (torvum), (viarum), wittei, (wrightii)
Republic of the Congo aculeastrum, anomalum, dasyphyllum, (lycopersicum), terminale, (torvum)
Cote d’Ivoire (aculeatissimum), americanum, anguivi, anomalum, cerasiferum, dasyphyllum, (lycopersicum), scabrum, terminale, (torvum)
Djibouti somalense
Egypt (incl. Hala’ib triangle)* coagulans, (diphyllum), dulcamara, elaeagnifolium, forskalii, incanum, (lycopersicum), macrocarpon, (melongena), memphiticum, nigrum, scabrum, (torvum), villosum, virginianum, (wendlandii), (wrightii)
Equatorial Guinea (aculeatissimum), aethiopicum, americanum, anguivi, dasyphyllum, giganteum, (lycopersicum), pseudospinosum, scabrum, terminale, (torvum)
Eritrea adoense, americanum, anguivi, campylacanthum, cerasiferum, coagulans, dasyphyllum, forskalii, glabratum, incanum, (lycopersicum), macracanthum, marginatum, melastomoides, (melongena), memphiticum, muricatum, scabrum, schimperianum, somalense, tarderemotum, terminale, villosum
Ethiopia (aculeatissimum), adoense, americanum, anguivi, arundo, campylacanthum, capsicoides, cerasiferum, coagulans, cordatum, dennekense, forskalii, giganteum, glabratum, hastifolium, hirtulum, incanum, jubae, lanzae, (lycopersicum), macracanthum, macrocarpon, marginatum, melastomoides, memphiticum, muricatum, pampaninii, runsoriense, schimperianum, somalense, tarderemotum, terminale, tettense, villosum, (wrightii)
Gabon aethiopicum, americanum, anguivi, anomalum, dasyphyllum, giganteum, macrocarpon, scabrum, terminale, (torvum), (wrightii)
Gambia americanum, anguivi, cerasiferum, dasyphyllum
Ghana (aculeatissimum), americanum, anguivi, anomalum, capsicoides, dasyphyllum, (erianthum), incanum, macrocarpon, (melongena), scabrum, tarderemotum, terminale, (torvum), (wrightii)
Guinea (aculeatissimum), anguivi, (erianthum), scabrum, tarderemotum, terminale, (torvum), (wrightii)
Guinea-Bissau americanum, anguivi, cerasiferum, dasyphyllum, terminale
Kenya aculeastrum, (aculeatissimum), aethiopicum, agnewiorum, americanum, anguivi, arundo, (betaceum), campylacanthum, coagulans, cordatum, dasyphyllum, dennekense, forskalii, giganteum, goetzei, hastifolium, incanum, jubae, lanzae, (laxum), (lycopersicum), macrocarpon, malindiense, mammosum, mauense, (mauritianum), melastomoides, (melongena), nigriviolaceum, pampaninii, phoxocarpum, polhillii, (pseudocapsicum), richardii, runsoriense, schumannianum, (seaforthianum), setaceum, sisymbrifolium, somalense, stipitatostellatum, taitense, tarderemotum, terminale, tettense, (tuberosum), usambarense, usaramense, villosum, (wendlandii), (wrightii), zanzibarense
Lesotho (aculeatissimum), (chenopodioides), lichtensteinii, retroflexum, scabrum, sodomeodes, tarderemotum
Liberia (aculeatissimum), americanum, anguivi, anomalum, dasyphyllum, (lycopersicum), (mauritianum), scabrum, terminale, (torvum)
Libya linnaeanum, nigrum, villosum, virginianum
Madagascar aethiopicum, americanum, anguivi, batoides, (betaceum), betroka, bumeliifolium, croatii, erythracanthum, heinianum, humblotii, imamense, insanum, ivohibe, (lycopersicum), macrocarpon, madagascariense, mahoriense, (mauritianum), (melongena), myoxotrichum, myrsinoides, (pseudocapsicum), pyracanthos, richardii, sambiranense, scabrum, (seaforthianum), tarderemotum, toliaraea, (torvum), trichopetiolatum, truncicola, (tuberosum), violaceum
Madeira (Portugal) (chenopodioides), dulcamara, (laxum), linnaeanum, (lycopersicum), marginatum, nigrum, (pseudocapsicum), trisectum, villosum
Malawi aculeastrum, (aculeatissimum), aethiopicum, americanum, anguivi, aureitomentosum, campylacanthum, (chrysotrichum), dasyphyllum, giganteum, goetzei, lichtensteinii, macrocarpon, retroflexum, richardii, scabrum, schumannianum, (seaforthianum), tarderemotum, terminale, tettense, (torvum), villosum, (wendlandii), (wrightii)
Mali cerasiferum, dasyphyllum, forskalii, incanum, (lycopersicum), tarderemotum
Mauritania dasyphyllum, scabrum, villosum
Mauritius (incl. La Réunion) americanum, (anguivi), (chenopodioides), erythracanthum, insanum, (lycopersicum), (mauritianum), (melongena), richardii, tarderemotum, (torvum), violaceum
Morocco dulcamara, elaeagnifolium, forskalii, herculeum, (laciniatum), linnaeanum, nigrum, triflorum, villosum
Mozambique aculeastrum, (aculeatissimum), aethiopicum, americanum, anguivi, aureitomentosum, campylacanthum, catombelense, dasyphyllum, giganteum, goetzei, lamprocarpum, lichtensteinii, linnaeanum, litoraneum, retroflexum, richardii, scabrum, stipitatostellatum, tarderemotum, tettense, torreanum, (torvum), usaramense, (viarum), villosum, zanzibarense
Namibia burchellii, campylacanthum, capense, catombelense, elaeagnifolium, numile, lichtensteinii, (lycopersicum), pimpinellifolium, retroflexum, scabrum, (seaforthianum), supinum, tarderemotum, tettense
Niger anguivi, forskalii, incanum, (lycopersicum), villosum
Nigeria aculeastrum, (aculeatissimum), aethiopicum, americanum, anguivi, anomalum, cerasiferum, dasyphyllum, (erianthum), giganteum, incanum, (lycopersicum), macrocarpon, melongena, scabrum, terminale, (torvum), villosum, (wrightii)
Rwanda aculeastrum, (aculeatissimum), anguivi, campylacanthum, cyaneopurpureum, dasyphyllum, giganteum, tarderemotum, terminale, wittei
São Tome e Principe americanum, capsicoides, (melongena), scabrum, terminale
Senegal anguivi, cerasiferum, forskalii, incanum, (lycopersicum), rigidum ?, scabrum, tarderemotum
Seychelles aldabrense, americanum, scabrum
Sierra Leone aculeatissimum, americanum, anguivi, capsicoides, dasyphyllum, (erianthum), (lycopersicum), macrocarpon, (melongena), scabrum, tarderemotum, terminale, (torvum), (wrightii)
Somalia arundo, campylacanthum, coagulans, cordatum, cymbalariifolium, dasyphyllum, dennekense, forskalii, glabratum, hastifolium, incanum, jubae, melastomoides, (melongena), memphiticum, pampaninii, schimperianum, somalense, tarderemotum, tettense, villosum
South Africa aculeastrum, (aculeatissimum), africanum, americanum, anguivi, burchellii, campylacanthum, capense, catombelense, (chenopodioides), (chrysotrichum), dasyphyllum, elaeagnifolium, giganteum, guineense, humile, (laxum), lichtensteinii, linnaeanum, (mauritianum), (pseudocapsicum), retroflexum, rubetorum, (sarrachoides), (seaforthianum), sisymbriifolium, sodomeodes, supinum, tarderemotum, terminale, tettense, tomentosum, torreanum, (torvum), triflorum, (viarum), (wrightii)
South Sudan aculeastrum, (aculeatissimum), aethiopicum, anguivi, campylacanthum, cerasiferum, coagulans, dasyphyllum, giganteum, hastifolium, scabrum, tarderemotum, terminale
Sudan (incl. Hala’ib triangle)* aculeastrum, adoense, aethiopicum, campylacanthum, cerasiferum, coagulans, forskalii, hastifolium, incanum, macrocarpon, memphiticum, nigrum, scabrum, schimperianum, somalense, tarderemotum, villosum
Swaziland aculeastrum, campylacanthum, catombelense, retroflexum, (robustum), (seaforthianum), sisymbriifolium, torreanum
Tanzania aculeastrum, (aculeatissimum), americanum, anguivi, arundo, (atropurpureum), aureitomentosum, (betaceum), campylacanthum, coagulans, cyaneopurpureum, dasyphyllum, dennekense, giganteum, goetzei, hastifolium, inaequiradians, lamprocarpum, lanzae, lichtensteinii, (lycopersicum), macrocarpon, mauense, (melongena), memphiticum, (pectinatum), phoxocarpum, polhillii, richardii, (robustum), scabrum, schliebenii, schumannianum, (seaforthianum), setaceum, stipitatostellatum, taitense, tarderemotum, terminale, tettense, thomsonii, (tuberosum), umalilaense, usambarense, usaramense, villosum, (wendlandii), wittei, (wrightii), zanzibarense
Togo (aculeatissimum), aethiopicum, americanum, anguivi, anomalum, (melongena), scabrum, terminale, (torvum)
Tunisia linnaeanum, (lycopersicum), nigrum, triflorum, villosum
Uganda aculeastrum, (aculeatissimum), aethiopicum, americanum, anguivi, (betaceum), campylacanthum, cerasiferum, coagulans, cyaneopurpureum, dasyphyllum, giganteum, hastifolium, lanzae, macrocarpon, mammosum, mauense, mauritianum, memphiticum, runsoriense, scabrum, schumannianum, (seaforthianum), tarderemotum, terminale, tettense, villosum, wittei, (wrightii)
Western Sahara villosum
Zambia (aculeatissimum), americanum, anguivi, aureitomentosum, campylacanthum, (chrysotrichum), goetzei, lichtensteinii, (lycopersicum), retroflexum, richardii, scabrum, (seaforthianum), tarderemotum, terminale, tettense, (torvum), (tuberosum), villosum, (wendlandii), (wrightii)
Zimbabwe aculeastrum. (aculeatissimum), anguivi, aureitomentosum, (betaceum), campylacanthum, catombelense, giganteum, lichtensteinii, linnaeanum, (mauritianum), retroflexum, richardii, scabrum, (seaforthianum), tarderemotum, terminale, villosum, (wendlandii)
Figure 1. 

Heat map of Solanum diversity in Africa. Darker degree squares indicate greater species richness. The middle to high elevation regions of eastern Africa (Kenya/Tanzania) have the highest high species diversity, followed by secondary areas of species richness in the Ethiopian plateaus, dry areas of central Madagascar, South Africa and the area around Mount Cameroon. We have not analysed how collecting effort has influenced these patterns, but it is likely to be important. As the Leptostemonum Clade has the largest number of species in Africa, diversity in that clade drives species richness overall (see Vorontsova and Knapp 2016, figure 2). Map prepared by Sarah Ficinski.

Materials and methods

We modified keys from published monographs for groups of Solanum from the botanical continent “Africa” as defined in the World Geographical Scheme for Recording Plant Distributions (WGSRPD; Brummitt 2001). This corresponds basically to the countries of the continent of Africa, but excludes the Sinai Peninsula (politically part of Egypt and in WGSRPD part of Western Asia). It also includes islands grouped as Macaronesia (Azores, Canary Islands, Madeira and the Cape Verde Islands ) and Madagascar and other Indian Ocean islands east to Rodrigues.

We assessed distribution using the published monographs, with additional data points added from subsequent herbarium visits. All specimens seen for these keys can be seen in the Supplemental File and in the dataset published on the NHM Data Portal (https://doi.org/10.5519/0042549). For descriptions of the taxa, users are referred to the original publications or the Solanaceae Source website (www.solanaceaesource.org), where all species treated here are described and synonymy listed.

To access descriptions on the Solanaceae Source website, begin by typing the species name in the search box in the upper right-hand part of the screen banner (tick the option “Taxonomy” below the box); when the correct name you are searching for appears, select it, then push the “Search” button to the right of the search box (if you do not push the “Search” button, nothing will happen). You will be taken to the species page, where images and synonyms appear on the opening page; to access descriptions, click on the “Description” tab where information can be obtained. Up-to-date specimen details are not currently available on the website but can be found as described above.

Keys

Solanum can be divided into 13 major clades or monophyletic groups (Bohs 2005; Weese and Bohs 2007; Särkinen et al. 2013; see Figures 2 and 3 for photographs illustrating representative morphology of these groups in Africa). The largest monophyletic clade is the Leptostemonum clade, or the “spiny solanums”, which comprises approximately half of the species diversity of the genus; divisions within that clade have been defined by Stern et al. (2011), Vorontsova et al. (2013) and Aubriot et al. (2016). This group is rapidly diversifying in the Old World (Echeverría-Londoño et al. 2018), with most taxa occurring in the Old World belonging to a single monophyletic group. Previous treatments (e.g. Whalen 1984; Jaeger 1985; Jaeger and Hepper 1986) had suggested the African taxa were members of, or closely related to New World groups. More information on the phylogenetic relationships of African and Asian members of the Leptostemonum Clade can be found in Vorontsova et al. (2013) and Aubriot et al. (2016). Other clades with significant species diversity in Africa (as defined here) are the African non-spiny (ANS) and Normania Clades (both endemic to the region; see Bohs and Olmstead 2001) and the Morelloid Clade (with a number of widespread weedy taxa, see Särkinen et al. 2018). Other clades such as the Geminata, Brevantherum and Potato Clades are represented only by introduced or cultivated species. The Dulcamaroid Clade has a single species native to Mediterranean northern Africa and Macaronesia and two cultivated taxa that can become naturalised (Knapp 2013). In order to facilitate identification and to assist with the discovery of novelties from the region, we provide a key to the major groups (clades) of Solanum following the most recent phylogeny of the genus (Särkinen et al. 2013) and additional dichotomous keys to the species within each group. Groups are ordered as they occur as branches in the phylogeny of Särkinen et al. (2013).

Figure 2. 

A, B Solanum wendlandii Hook.f. (Allophyllum-Wendlandii Clade) C Solanum tarderemotum Bitter (Morelloid Clade) D Solanum scabrum Mill. (Morelloid Clade) E Solanum pyracanthos Lam. (Leptostemonum Clade) F Solanum aculeastrum Dunal (Leptostemonum Clade) G Solanum nigriviolaceum Bitter (Leptostemonum Clade) H Solanum usambarense Bitter & Dammer (Leptostemonum Clade). Photos A, B, F, G H by M.S. Vorontosova C, D, E by S. Knapp.

Figure 3. 

A Solanum terminale Forssk. (African non-spiny Clade) B Solanum madagascariense Dunal (African non-spiny Clade) C Solanum mauritianum Scop. (Brevantherum Clade) D Solanum laxum Spreng. (Dulcamaroid Clade) E Solanum trisectum Dunal (Normania Clade) F Solanum diphyllum L. (Geminata Clade) G Solanum tuberosum L. (Potato Clade) H Solanum laciniatum Aiton (Archaeosolanum Clade). Photos A, C, D, E, F, G, H by S. Knapp B by M.S. Vorontsova.

Four species have been recorded from this area, for which we have only seen single specimens, all of which are cultivated and not naturalised. Solanum laciniatum Aiton (Archaesolanum Clade), the kangaroo apple from Australia and New Zealand, has been recorded from Morocco, S. agrarium Sendtn. (Leptostemonum Clade, section Acanthophora Dunal sensu Nee 1979) from Brazil has only recently been collected in the Cape Verde Islands and S. atropurpureum Schrank (Leptostemonum Clade, section Acanthophora Dunal sensu Nee 1979) from Brazil and S. pectinatum Dunal (Leptostemonum Clade, section Lasiocarpa Dunal sensu Whalen et al. 1981) from Mexico have been recorded from Tanzania in a botanical garden. These singletons have been included in Table 1, but not in the keys below; descriptions should be checked if identification is ambiguous.

Each species name is hyperlinked to its page on Solanaceae Source (www.solanaceaesource.org) where photographs (if available), descriptions and other information can be found. An expanded key to all of the thirteen major clades of Solanum worldwide is in preparation (R. Hilgenhof and T. Särkinen, pers. comm.). Instructions on how to use Solanaceae source are included in the Materials and Methods.

Key to the groups of Solanum in continental Africa, Madagascar (incl. the islands of Réunion, the Comoros and the Seychelles), Macaronesia and the Cape Verde Islands

1a Trichomes of stems and leaves stellate or echinoid 2
1b Trichomes of stems and leaves simple (unbranched) or dendritically branched, never stellate or echinoid 3
2a Anthers ellipsoid in outline; inflorescences many times branched; branching dichasial; stems without prickles Key 6. Brevantherum Clade
2b Anthers tapering in outline; inflorescences branched or unbranched; branching monochasial; stems with or without prickles Key 7. Leptostemonum Clade
3a Shrubs, small trees or woody vines 4
3b Herbs or if plants woody, only at the base; never true vines, occasionally scandent 9
4a Stems with hooked prickles; anthers tapering Solanum wendlandii Hook.f. (Wendlandii-Allophyllum Clade)
4b Stems without prickles; anthers ellipsoid 5
5a Small trees with foetid cordate leaves; flowers waxy pink or greenish white; anther connectives enlarged; fruit a large turbinate berry with fleshy pulp; cultivated tree tomato Solanum betaceum Cav. (Pachyphylla [Cyphomandra] Clade)
5b Shrubs or woody vines; leaves, flowers and anther connectives not as above 6
6a Small shrubs with paired (geminate) leaves; flowers nodding, white; fruit held on erect pedicels, orange; cultivated or occasionally naturalised in northern Africa 7
6b Woody vines or scandent shrubs; leaves, flowers and fruit not as above; continental Africa, Madagascar; or cultivated 8
7a Leaves lanceolate, with at least some branched trichomes on new growth; leaves of a pair more or less the same shape; inflorescence usually with 2 flowers; berry dark orange; cultivated “Jerusalem cherry” Solanum pseudocapsicum L. (Geminata Clade)
7b Leaves ovate or elliptic, completely glabrous; leaves of a pair markedly different in shape; inflorescence with more than 2 flowers; berry pale orange; only recorded from Egypt Solanum diphyllum L. (Geminata Clade)
8a Base of pedicel enclosed in a small sleeve of rhachis tissue usually more than 0.5 mm long; Mediterranean northern Africa; Macaronesia; if in other parts of Africa, cultivated Key 3. Dulcamaroid Clade
8b Base of pedicel peg-like, sometimes enclosed in a small sleeve of rhachis tissue, if so the sleeve less than 0.5 mm long; Continental tropical Africa; Madagascar; native plants Key 1. African non-spiny (ANS) Clade
9a Leaves pinnate or deeply pinnatifid 11
9b Leaves simple (at most the margins toothed) or at most ternate 12
10a Fleshy prostrate herbs; leaves pinnatifid, the leaflets not distinct; inflorescences unbranched Solanum triflorum Nutt. (Morelloid Clade)
10b Spreading herbs or herbaceous scramblers, not fleshy; leaves pinnate with distinct leaflets; inflorescences branched or less often unbranched Key 5. Potato Clade
11a Anthers dimorphic, of different sizes and two of the five with horn-like projections; Macaronesia and northern Africa Key 2. Normania Clade
11b Anthers equal in size and shape, if unequal only slightly so; widespread or cultivated 12
12a Trichomes simple with a single long terminal cell (bayonet hairs); fruit a large greenish berry with purple stripes (more than 3 cm diameter), with abundant solid mesocarp; herbaceous vine Solanum muricatum Aiton (Potato Clade)
12b Trichomes simple or branched; fruit variously coloured (usually less than 1 cm in diameter), with juicy mesocarp; annual or short-lived perennial herbs Key 4. Morelloid Clade

Key 1. African non-spiny (ANS) Clade (descriptions Knapp and Vorontsova 2016)

1a Leaves glabrous on both surfaces 2
1b Leaves with at least some pubescence on either surface (this sometimes sparse along veins and midrib) 10
2a Inflorescence few-flowered, unbranched (at most furcate in Solanum betroka) 3
2b Inflorescence many flowered, usually many times branched 5
3a Flowers appearing fasciculate and axillary; corolla usually somewhat campanulate; fruit orange; South Africa Solanum guineense L.
3b Flowers not appearing fasciculate; corolla stellate, the petals spreading or reflexed; fruit colour green, black or not known, never orange; Madagascar 4
4a Leaves clustered on short shoots; calyx lobes deltate, not divided to base; dry forests Solanum betroka D’Arcy & Rakot.
4b Leaves not clustered on short shoots; calyx lobes long triangular, divided to the base; wet forests Solanum truncicola D’Arcy & Rakot.
5a Flowers or fruits (or pedicel scars) in tightly packed groups on individual branches (these sometimes very short and the inflorescence appearing spicate) Solanum terminale Forssk.
5b Flowers spaced on the open inflorescence, often unevenly so 6
6a Leaves clustered on short shoots Solanum betroka D’Arcy & Rakot.
6b Leaves spaced along the stem 7
7a Anthers opening by pores that elongate with age; mountains of continental Africa Solanum runsoriense C.H.Wright
7b Anthers opening by delineated pores that do not elongate with age; Madagascar 8
8a Leaves fleshy, thick and coriaceous, the venation not visible in dry specimens; fruit with thick pericarp (woody?) Solanum myrsinoides D’Arcy & Rakot.
8b Leaves membranous to coriaceous, not markedly thick and fleshy, the venation visible in dry specimens; fruit with thin pericarp, the seeds visible through the berry wall 9
9a Petioles with long, simple trichomes (these not extending to the lamina); seeds 4–8 per berry; inflorescence axis thin and delicate Solanum trichopetiolatum D’Arcy & Rakot.
9b Petioles glabrous or with minute dendritic trichomes; seeds 20–40 per berry; inflorescence axis robust Solanum madagascariense Dunal
10a Leaf trichomes simple (unbranched) 11
10b Leaf trichomes branched (dendritic to echinoid) 16
11a Inflorescence axis unbranched, the flowers closely spaced 12
11b Inflorescence axis branched, often many times so 13
12a Leaves clustered along stem; fruit orange; South Africa Solanum guineense L.
12b Leaves spaced along shoots; fruit purple or black; Madagascar Solanum truncicola D’Arcy & Rakot.
13a Flowers or fruits (or pedicel scars) in tightly packed groups on individual branches (these sometimes very short and the inflorescence appearing spicate) Solanum terminale Forssk.
13b Flowers spaced on the open inflorescence, often unevenly so 14
14a Stems strongly quadrangular; at least some leaves with shallow lobes; plants of seashore and dune habitats Solanum africanum Mill.
14b Stems terete; leaves not lobed; plants of forests and forest edges 15
15a Leaf pubescence very sparse, confined to the midrib or near the petiole; flowers not heterostylous; Madagascar Solanum trichopetiolatum D’Arcy & Rakot.
15a Leaf pubescence variable, not very sparse, along veins and lamina; flowers heterostylous; mountains of continental Africa Solanum runsoriense C.H.Wright
16a Abaxial leaf surfaces with tufts of trichomes in the vein axils (domatia) 17
16b Abaxial leaf surfaces with trichomes on lamina and/or along veins, not with prominent tufts in the vein axils (domatia) 19
17a Inflorescence many times branched, open and with many flowers (more than 20); calyx lobes broadly deltate; petioles to 4 cm long, thin and flexuous; Mayotte (Comoros) Solanum macrothyrsum Dammer
17b Inflorescence furcate, more congested and with fewer flowers (fewer than 20); calyx lobes deltate; petioles to 2.5 cm long, thicker; Madagascar 18
18a Calyx lobes 0.8–2 mm long; inflorescences with 10–16 flowers Solanum ivohibe D’Arcy & Rakot.
18b Calyx lobes 4–6 mm long; inflorescences with 3–10 flowers Solanum sambiranense D’Arcy & Rakot.
19a Abaxial leaf surfaces evenly pubescent on veins and lamina 20
19b Abaxial leaf surfaces pubescent only along the veins and midrib, the trichomes not extending to the lamina 22
20a Anther pores lengthening to slits with age; flowers heterostylous; leaves evenly distributed along branches; mountains of continental Africa Solanum runsoriense C.H.Wright
20b Anther pores not lengthening to slit with age; flowers not heterostylous; leaves usually at least somewhat clustered on short shoots; Madagascar 21
21a Leaves densely pubescent with golden (when dry) loosely dendritic trichomes; flowers more than 2 cm in diameter; anthers 4–6 mm long; widespread in Madagascar Solanum imamense Dunal
21b Leaves sparsely pubescent with white (when dry) congested dendritic trichomes; flowers 2 cm in diameter or less; anthers 3.5–4 mm long; dry forests of southern Madagascar Solanum betroka D’Arcy & Rakot.
22a Inflorescence unbranched, with few flowers; pedicels 1.8–4.5 cm long Solanum humblotii Bitter
22b Inflorescence many times branched, with many flowers; pedicels 0.8–1.2 cm long 23
23a Anther pores lengthening to slits with age; flowers heterostylous; pedicels with pubescence like the inflorescence rhachis; mountains of continental Africa Solanum runsoriense C.H.Wright
23b Anther pores not lengthening to slit with age; flowers not heterostylous; pedicels always glabrous; Madagascar Solanum madagascariense Dunal

Key 2. Normania clade (descriptions on Solanaceae Source)

1a Leaves shallowly lobed, pubescent with long, tangled eglandular trichomes; anthers tapering, horned near the base, tightly connivent; seeds more than 5 mm long; fruit a dry berry; Mediterranean Solanum herculeum Bohs
1b Leaves simple or ternate, glabrous or pubescent, but the trichomes not long and tangled, glandular; anthers markedly horned, spreading; seeds less than or equal to 5 mm long; fruit a brightly coloured, juicy berry; laurisylva forest in Macaronesia 2
2a Leaves simple or ternate, the base truncate or cordate if leaves unlobed; anthers yellow, horned in lower third; berry bright red; Madeira Solanum trisectum Dunal
2b Leaves simple, the base cordate; anthers black, horned about halfway up from the base; berry orange or red; Tenerife, Canary Islands Solanum nava Webb & Berthel.

Key 3. Dulcamaroid clade (descriptions in Knapp 2013 and on Solanaceae Source)

1a Buds turbinate and strongly pointed; petals strongly reflexed, with shiny green dots at the base of each; anthers tightly connivent with “glue”; fruit a shiny red berry, often ellipsoid; native plants in Mediterranean northern Africa Solanum dulcamara L.
1b Buds rounded, often somewhat inflated; petals spreading, without shiny green dots; anthers not tightly connivent with “glue”; fruit red or black, globose; cultivated plants, occasionally naturalised throughout the region 2
2a Flowers white; anthers on equal filaments; leaves with axillary tufts of trichomes on the lower surfaces (domatia), usually simple, occasionally pinnatifid; berry (very rarely) black Solanum laxum Spreng.
2b Flowers purple; one filament slightly longer than the other 4; leaves completely glabrous, pinnatifid, rarely simple; berry bright shiny red Solanum seaforthianum Andrews

Key 4. Morelloid clade (descriptions in Särkinen et al. 2018 and on Solanaceae Source)

1a Leaves shallowly to deeply pinnatifid Solanum triflorum Nutt.
1b Leaves entire to sinuate-dentate 2
2a Glandular trichomes present (e.g. along stems, petioles and leaves), plants usually sticky to touch when fresh 3
2b Glandular trichomes absent (e.g. along stems, petioles and leaves), plants not sticky to touch when fresh 14
3a Anthers less than 1.8 mm long 4
3b Anthers more than or equal to 1.8 mm long 7
4a Inflorescences with 10–40 flowers; pedicels spaced 1–2 mm apart, sharply bent at the base (near articulation point) in flower and fruit Solanum tarderemotum Bitter
4b Inflorescences with 2–5(-10) flowers; pedicels spaced 0–1 mm apart, nodding, erect or spreading in flower and fruit, reflexed and slightly curved in some species in fruit but never in flower 5
5a Calyx lobes 1–1.5 mm long in flower; fruiting calyces not accrescent, the tube remaining 1–1.7 mm long and lobes 1–1.5 mm long; fruit black when ripe, not markedly shiny, with a glaucous cast Solanum retroflexum Dunal
5b Calyx lobes 1.5–2.5 mm long in flower; fruiting calyces accrescent, the tube 3–4 mm long and lobes 2.5–8.0 mm long; fruit green when ripe, shiny 6
6a Leaf bases attenuate to cuneate; inflorescences mostly intermodal, with 4–8(-10) flowers; pedicels spaced 0.3–1 mm apart; calyx lobes 1.7–2.5 mm long; corollas with yellow-green central eye with black-purple V-shaped margins; anthers 1.0–1.4 mm long; berries dark green to green-brown marbled with white lines, becoming usually translucent and glossy, lower half of berries covered with enlarged calyces but berry mostly visible; seeds brown; stone cells (1-)2–3, these 0.5 mm in diameter; northern Africa Solanum nitidibaccatum Bitter
6b Leaf bases truncate; inflorescences mostly leaf-opposed, with 2–5(-7) flowers; pedicels spaced 0(-1) mm apart; calyx lobes 1.5–2.0 mm long; corolla with yellow-green or translucent basal star without black-purple colouration; anthers 1.2–2.0 mm long; berries pale green, shiny becoming dull, opaque, usually completely enveloped by enlarged calyces; seeds pale yellow; stone cells 4–6, these (0.5-)0.8–1 mm in diameter; only known from South Africa Solanum sarrachoides Sendtn.
7a Anthers more than or equal to 2.8 mm long 8
7b Anthers less than 2.8 mm long 9
8a Inflorescences with bracteoles present in most individuals; buds narrowly ellipsoid; corolla deeply stellate, the lobes narrowly lanceolate; berries with more than 30 stone cells Solanum triflorum Nutt.
8b Inflorescences never with bracteoles; buds globose, ovoid or narrowly ellipsoid; corolla rotate-stellate, the lobes long- triangular with rounded tips; berries with (0-)2–4 stone cells Solanum memphiticum Forssk.
9a Calyx lobes appressed to spreading in fruit, never strongly reflexed 10
9b Calyx lobes strongly reflexed in fruit 12
10a Calyx accrescent in fruit, calyx tube 3–4 mm long and lobes 2.5–8 mm long Solanum sarrachoides Sendtn.
10b Calyx not accrescent in fruit, calyx tube 1–2 mm long and lobes 1–1.5 mm long 11
11a Buds ellipsoid; calyx tube 1.5–2.0 mm long, lobes 1–1.5 mm long, elongate-deltate with rounded tips; fruiting pedicels persist when fruits mature and fall off; Cameroon line (Cameroon and Equatorial Guinea), above 2,000 m elevation Solanum pseudospinosum C.H.Wright
11b Buds subglobose; calyx tube 0.8–1.0 mm long, lobes 0.5–0.8 mm long, triangular with rounded to acute tips; fruiting pedicels generally do not persist and fall off with maturing fruits; in continental Africa only in South Africa and around the Mediterranean Solanum nigrum L.
12a Leaves rhomboidal to lanceolate; filaments 1.2–1.5 mm long, anthers 1.3–1.8(-2) mm long; seeds 1.6–1.8 mm long and 1.3–1.5 mm wide Solanum retroflexum Dunal
12b Leaves broadly to narrowly ovate to elliptic; filaments 0.5–1.3 mm long; anthers 1.8–2.5 mm long; seeds 1.8–2.2 mm long and 1.5–1.7 mm wide 13
13a Calyx with broad and relatively transparent sinuses, lobes elliptic to triangular, rounded at tip; free part of the filaments 1.0–1.3 mm long; mature berries slightly ellipsoid, shiny yellow, orange or red; stone cells always absent Solanum villosum Mill.
13b Calyx with narrow, sharp triangular sinuses, lobes deltate with acute or rounded tips; free part of the filaments 0.5–0.7 mm long; mature berries round, dull black or green; stone cells 0–4; in Africa only in South Africa and around the Mediterranean Solanum nigrum L.
14a Anthers less than 1.8 mm long 15
14b Anthers more than or equal to 1.8 mm long 17
15a Pedicels spaced 1–2 mm apart, pedicels sharply bent at the base (near the articulation point) in flower and fruit Solanum tarderemotum Bitter
15b Pedicels spaced 0–0.5 mm apart, pedicels nodding, erect or spreading in flower and fruit 16
16a Leaves with entire margins, occasionally sinuate-dentate; calyx lobes 0.3–0.5 mm long in flower, 1(-2) mm in fruit; mature fruits black, the surface very shiny Solanum americanum Mill.
16b Leaves shallowly toothed, occasionally entire; calyx lobes 1.0–1.5 mm long in flower, 1.5–2 mm in fruit; mature fruits purple-black or green, the surface dull Solanum retroflexum Dunal
17a Anthers less than 2.8 mm long 18
17b Anthers more than or equal to 2.8 mm long 27
18a Berries without stone cells 19
18b Berries with 2–22 stone cells 24
19a Pedicels persisting and not dropping with mature fruits; calyx lobes in fruit mostly strongly reflexed 20
19b Pedicels dropping with mature fruits; calyx lobes in fruit appressed to slightly spreading, rarely strongly reflexed 22
20a Leaves rhomboidal to lanceolate; filaments 1.2–1.5 mm long, anthers 1.3–1.8(-2) mm long; seeds 1.6–1.8 mm long and 1.3–1.5 mm wide Solanum retroflexum Dunal
20b Leaves broadly to narrowly ovate to elliptic; filaments 0.5–1.3 mm long; anthers 1.8–2.5 mm long; seeds 1.8–2.2 mm long and 1.5–1.7 mm wide 21
21a Calyx with broad and relatively transparent sinuses, lobes elliptic to triangular, rounded at tip; filaments 1.0–1.3 mm long; mature berries slightly ellipsoid, shiny yellow, orange or red; stone cells always absent Solanum villosum Mill.
21b Calyx with narrow, sharp triangular sinuses, lobes deltate with acute tips; filaments 0.5–0.7 mm long; mature berries round, dull black or green; stone cells generally absent (2–4 stone cells common in Asian material) Solanum nigrum L.
22a Buds elongate-oblong; fruiting peduncles strongly deflexed at the base (bent downwards at junction with the stem) Solanum chenopodioides Lam.
22b Buds ellipsoid to subglobose; fruiting peduncles straight or ascending 23
23a Pedicels spaced 1–2 mm apart, sharply bent at the base (near the articulation point) in flower and fruit; seeds 1.5–2 mm long and 1–1.5 mm wide Solanum tarderemotum Bitter
23b Pedicels spaced 0–0.7 mm apart, straight, spreading or reflexed in flower and fruit; seeds 1.8–2 mm long and 1.5–1.6 mm wide Solanum nigrum L.
24a Prostrate herb; leaves narrowly elliptic to lanceolate, base strongly attenuate; inflorescences with 1–5 flowers; pedicels stout and spreading; calyx lobes linear-oblong with rounded apices; mountains of Ethiopia Solanum hirtulum C.H.Wright
24b Upright or spreading herb; leaves broadly ovate to elliptic, base acuminate, acute, obtuse, truncate to abruptly attenuate; inflorescences with 2–40 flowers; pedicels thinner, spreading to strongly reflexed; calyx lobes triangular, broadly deltoid or ovate with acute to rounded apices 25
25a Pedicels strongly bent downwards at the base (near articulation point) in flower and fruit Solanum tarderemotum Bitter
25b Pedicels spreading, stout or pendent in flower, occasionally recurved in fruit but never strongly bent downwards at the base 26
26a Inflorescences unbranched or more often branched, often with small leaves (bracteoles?); calyx lobes broadly deltate to mere enations of the rim; style exserted 1.0–1.5 mm beyond anther cone; mature berries 3–4(-5) mm in diameter, dull yellowish brown Solanum umalilaense Manoko
26b Inflorescences unbranched, never with small leaves; calyx lobes triangular; style exserted 0–1 mm beyond anther cone; mature berries 6–10 mm in diameter, dull black Solanum nigrum L.
27a Inflorescences with bracteoles present in most individuals; buds narrowly elliptic; berries with more than 30 stone cells Solanum triflorum Nutt.
27b Inflorescences never with bracteoles; buds globose, ovoid or narrowly ellipsoid; berries with 0–14 stone cells 28
28a Berries with 2–14 stone cells; leaf base strongly attenuate Solanum hirtulum C.H.Wright
28b Berries without stone cells; leaf base not strongly attenuate 29
29a Buds elongate-oblong; calyx lobes broadly deltate to triangular with acute tips; fruiting peduncles strongly bent at the base near junction with the stem; fruiting pedicels thin, reflexed and slightly recurved; seeds 1.2–1.4 mm long and 1.0–1.2 mm wide Solanum chenopodioides Lam.
29b Buds globose-subglobose; calyx lobes broadly deltate with rounded tips; fruiting peduncles straight; fruiting pedicels stout, erect and spreading; seeds 2–2.8 mm long and 1.5–1.8 mm wide Solanum scabrum Mill.

Key 5. Potato clade (descriptions on Solanaceae Source)

1a Flowers yellow; anthers tightly connivent and tapering to a beak-like tip; fruit a bright red berry; cultivated tomatoes 2
1b Flowers white or purple; anthers ellipsoid, not tapering to a beak-like tip; fruit green or whitish green (often with purple stripes) 3
2a Corolla lobes deltate to triangular; anther cone stout, the style included; berry usually more than 1 cm in diameter (often much larger), fewer than 20 per infructescence; leaflets with serrate margins; cultivated tomato Solanum lycopersicum L.
2b Corolla lobes narrowly triangular; anther cone long and narrow, the style exserted; berry less than 1 cm in diameter, more than 20 per infructescence; leaflets with entire margins; cultivated currant tomato Solanum pimpinellifolium L.
3a Leaves at most ternate, usually simple; fruit a berry more than 3 cm in diameter; plant not bearing underground tubers; cultivated pepino Solanum muricatum Aiton
3b Leaves pinnate; fruit a berry less than 3 cm in diameter; plant bearing underground tubers; cultivated potato Solanum tuberosum L.

Key 6. Brevantherum clade (descriptions on Solanaceae Source)

1a Young flower buds turbinate; calyx densely pubescent within over entire surface; young stems sulcate; axillary leaves absent Solanum erianthum D.Don
1b Young flower buds oblong to orbicular; calyx lobes pubescent within only in distal quarter; young stems terete; axillary leaves common Solanum mauritianum Scop.

Key 7. Leptostemonum clade (descriptions in Vorontsova and Knapp 2016 and on Solanaceae Source)

1a Young stems and petioles noticeably winged; mature fruit densely pubescent; invasive plant in Tanzanian highlands and South Africa Solanum robustum H.Wendl.
1b Young stems and petioles not markedly winged (terete or slightly ridged); mature fruit glabrous; native or invasive, widespread 2
2a Flowers with stamens of differing lengths (due either to unequal anthers or unequal filaments or both); arid eastern and north-eastern Africa 3
2b Flowers with all stamens equal in length; widespread 8
3a Corolla strongly zygomorphic, with the two lower lobes much larger; flowers often enantiostylous; Canary Islands 4
3b Corolla only weakly zygomorphic, the lower lobes somewhat but not markedly larger; flowers not enantiostylous; continental Africa 5
4a Leaves narrowly elliptic to lanceolate; calyx lobes linear and awn-like; corolla always 5-merous; ripe berry orange; Gran Canaria Solanum lidii Sunding
4b Leaves ovate; calyx lobes linear; corolla often 4-merous; ripe berry yellow or yellowish green; Tenerife and Gran Canaria Solanum vespertilio Aiton
5a Leaves orbicular to reniform, 1.2–2.5 cm long, wider than long; petioles longer than leaves; rare in north-eastern Somalia Solanum cymbalariifolium Chiov.
5b Leaves ovate to elliptic or lanceolate, 2–14 cm long, longer than wide; petioles shorter than leaves; arid eastern and north-eastern Africa 6
6a Stem prickles dense, acicular, less than 0.5 mm wide at base, pale yellow; fruit fully concealed by the accrescent calyx Solanum coagulans Forssk.
6b Stem prickles absent or sparse, if present wider than 1 mm at base, yellow to orange or brown; fruit at least partly exposed 7
7a Leaves subentire to lobed; anthers of equal length; seeds very dark brown to almost black Solanum melastomoides C.H.Wright
7b Leaves entire; one anther much longer than the others; seeds dull yellow to orange-brown Solanum somalense Franch.
8a Flower one per inflorescence, peduncle and rhachis absent; corolla pentagonal, lobed for 1/4–1/3 of the way to the base, 0.9–1.3 cm in diameter; southern Africa Solanum supinum Dunal
8b Flower usually more than one per inflorescence, peduncle and/or rhachis present in at least some inflorescences; corolla usually stellate, lobed for more than 1/3 of the way to the base or, if lobed, for 1/4–1/3 of the way to the base then corolla of long-styled flowers broader than 1.3 cm in diameter; widespread 9
9a Trichomes on young stems and adaxial (upper) surfaces of the leaves simple only, never stellate 10
9b Trichomes on young stems and adaxial (upper) surfaces of the leaves stellate 13
10a Flowers pale bluish purple; anthers 8–12.5 mm; fruit globose or extended into a “nipple” Solanum mammosum L.
10b Flowers white or greenish white; anthers 5–7.5 mm; fruit globose 11
11a No stellate hairs anywhere on the plant; fruit bright orange at maturity; seeds winged, 4–6 mm long Solanum capsicoides All.
11b Stellate hairs almost always present on the abaxial (lower) surface of the leaves; fruit yellow at maturity; seeds not winged, 1.8–2.8 mm long 12
12a Leaf lobes 2–3 pairs, extending 1/3–1/2 distance to the midvein; calyx lobes 5–6.5 mm long, often caudate Solanum aculeatissimum Jacq.
12b Leaf lobes 3–5 pairs, extending less than 1/3 of the distance to the midvein; calyx lobes 0.8–2 mm long, acute Solanum viarum Dunal
13a Leaves entire, 3–10 times longer than wide; shrubs erect, 1–6 m tall; stem trichomes with partly fused rays; southern Madagascar 14
13b Leaves entire or lobed, 1–3(8) times longer than wide; shrubs erect, scandent or climbing, 0.2–6 m tall; if leaves entire and more than 3 times longer than wide, then shrub less than 1 m tall and not in southern Madagascar; stem trichomes with free rays 16
14a Leaves 9–13(20) cm long; corolla 2–3.1 cm in diameter; juvenile branches with dark red prickles; south-eastern Madagascar Solanum croatii D’Arcy & Keating
14b Leaves 1.5–7 cm long; corolla 1–2 cm in diameter; juvenile branches with grey-brown or red-brown prickles; south-western Madagascar 15
15a Leaf blades 3–7 cm long, concolorous to weakly discolorous, yellow-green Solanum bumeliifolium Dunal
15b Leaf blades 1.5–3(4) cm long, strongly discolorous, green-brown adaxially and glaucous abaxially Solanum heinianum D’Arcy & Keating
16a Prickles and leaf venation noticeably dark orange to red, contrasting with the yellow-green to red-green leaf surface; southern Madagascar Solanum pyracanthos Lam.
16b Prickles and leaf venation not a contrasting colour, yellow to green or red-brown; widespread or naturalised 17
17a Mature fruit green, never developing to bright yellow, orange or red; plants weakly andromonoecious; fruits 1–1.5 cm in diameter 18
17b Mature fruit yellow, orange or red; plants hermaphroditic or andromonoecious, fruits 0.5–6 cm in diameter, if andromonoecious, then fruits more than 1.5 cm in diameter 19
18a Shrub to tree 1.5–9 m tall; young stems and leaves densely ferruginous pubescent; trichomes on the inflorescences and pedicels not glandular; prickles straight to slightly curved Solanum chrysotrichum Schltdl.
18b Shrub to 3 m; young stems and leaves pubescent green to brownish; trichomes on the inflorescences and pedicels glandular; prickles curved Solanum torvum Sw.
19a Mature fruit yellow or greenish yellow, 1.5–5(6) cm in diameter; corolla on long-styled flowers (1.3)2–6 cm in diameter; plants mostly andromonoecious 20
19b Mature fruit orange to red, 0.5–1.2(1.7) cm in diameter; if mature fruit orange (1)1.5–2.5(5) cm in diameter, the plant cultivated; corolla on long-styled flowers 0.8–3 cm in diameter; plants mostly hermaphroditic 45
20a Cultivated tree 5–10 m tall with copious flowers; corolla bright purple aging to white with both colours usually present in an inflorescence, 5.5–8 cm in diameter Solanum wrightii Benth.
20b Wild plants or cultivated vegetables, less than 6 m tall; corolla white to mauve or purple with the colour constant within each individual, 1.6–6 cm in diameter 21
21a Petiole usually decurrent, leaf bases attenuate (cuneate); trichomes on abaxial leaf surface (if present) stalked with 4(5) rays 22
21b Petiole never decurrent, leaf bases cordate to cuneate; trichomes on abaxial leaf surface (if present) sessile or stalked with 6–16 rays 23
22a Plant clearly stellate-pubescent and armed, drying yellow-green to red-brown; wild plant Solanum dasyphyllum Schumach, & Thonn.
22b Plant usually glabrous and unarmed, drying a distinctive red-brown colour; cultivated plant Solanum macrocarpon L.
23a Climbers or scandent plants 24
23b Plants erect or rarely semi-scandent 27
24a Prickles on young stems straight 25
24b Prickles on young stems strongly curved 26
25a Prickles pale straw-yellow, to 20 mm long; petiole with sessile stellate trichomes; corolla ca. 2.5 cm in diameter; style strongly curved; Mediterranean northern Africa (adventive from Asia) Solanum virginianum L.
25b Prickles yellow (but not straw-coloured) or brown; petiole trichomes usually stalked; corolla 3.5–5 cm in diameter; style straight; southern Kenya Solanum nigriviolaceum Bitter
26a Corolla white, 1.3–1.6 cm in diameter; seeds 5.5–6 mm long; Kenyan mountains Solanum agnewiorum Voronts.
26b Corolla mauve to purple, 3.5–6 cm in diameter; seeds 3–4 mm long; eastern and southern Africa, Madagascar Solanum richardii Dunal
27a Calyx inflated, fully covering the berry at maturity; young stems densely covered with straight prickles; northern Madagascar Solanum mahoriense D’Arcy & Rakot.
27b Calyx not inflated, the berry exposed at maturity; young stems prickly or unarmed; widespread 28
28a Corolla lobed for more than half way to the base; shrubs or trees up to 6 m; variety of habitats 29
28b Corolla lobed for half way to the base or less; small shrubs up to 2 m; weeds of open arid environments or cultivated crops; relatives of the eggplant 35
29a Leaves 8–18 cm long, strongly discolorous; young fruits plain green; seeds 3.5–4.5 mm long; wet upland habitats 30
29a Leaves 2–8 cm long, concolorous or sometimes discolorous; young fruits striped in different shades of green; seeds 2.2–3.5 mm long; arid upland or lowland habitats 32
30a Fruit globose, never apiculate, 1.4–1.7 cm in diameter, 4–10 per infructescence; young stems with yellow (when dry) long-stalked trichomes, the stalks 1–3 mm Solanum thomsonii C.H.Wright
30b Fruit turbinate or cone-shaped, sometimes globose, usually somewhat apiculate, 2.8–5 x 1.8–4.5 cm, 1–3(5) per infructescence; young stems usually lacking long-stalked yellow (when dry) trichomes 31
31a Fruit distinctly turbinate or cone-shaped, 2.8–3.7 x 1.8–2.2 cm; leaves on fertile branches elliptic and subentire, 6–8 x 2.5–4 cm, ca. 2.5 times longer than wide; 2100–3000 m elevation Solanum phoxocarpum Voronts.
31b Fruit globose, usually somewhat apiculate, 3–5 x 2–4.5 cm; leaves on fertile branches ovate(elliptic) and lobed(subentire), 8–15 x 6–12 cm, 1.5–2 times longer than wide; 1200–2100(3200) m elevation Solanum aculeastrum Dunal
32a Prickles straight or occasionally curved; petioles 1/3–2/3 as long as the leaf blades Solanum polhillii Voronts.
32b Prickles on young stems strongly curved; petioles less than 1/3 of the leaf blade length 33
33a Leaves entire, densely stellate-pubescent on both sides; eastern and north-eastern African highlands Solanum dennekense Dammer
33b Leaves lobed, adaxially glabrescent; eastern and north-eastern Africa 34
34a Leaves 2–4 cm long; curved prickles on young stems 5–10 mm long; eastern and north-eastern Africa Solanum arundo Matthei
34b Leaves 6–8 cm long; curved prickles on young stems 1–3 mm long; coastal Kenya, rare Solanum malindiense Voronts.
35a Fruit with soft pericarp, in a variety of shapes and colours, edible; common fasciation in the flowers (e.g. increase in the number of flower parts up to 8), inflated ovaries; cultivated species Solanum melongena L.
35a Fruit spherical, yellow, with comparatively hard pericarp, not edible; flowers 5-merous; wild plants 36
36a Leaves lobed with primary and secondary lobes, the primary lobes extending 2/3–3/4 of the distance to the midvein and secondary lobes always present; southern Africa and northern African coasts around the Mediterranean Solanum linnaeanum Hepper & P.M-L.Jaeger
36b Leaves entire or lobed, lobes extending up to 2/3 of the distance to the midvein, secondary lobes usually not present; widespread 37
37a Leaf margins and venation nearly white and contrasting with greenish red-brown adaxial leaf surface; trichomes on the abaxial surface of the leaves with 10–17 rays; Ethiopian highlands Solanum marginatum L.f.
37b Leaf margins and venation the same colour as the rest of the leaf blade; trichomes on the abaxial surface of the leaves with 5–12(15) rays; widespread 38
38a Leaf lobes apically obtuse to acute, sometimes rounded, sometimes with secondary lobes; lobes 1/4–2/3 of the distance to the midvein; leaves and young stems glabrescent to moderately pubescent 39
38b Leaf lobes apically rounded, sometimes obtuse, never with secondary lobes; lobes up to 1/3(1/2) of the distance to the midvein; leaves and young stems usually densely pubescent 41
39a Calyx lobes on long-styled flowers 7–10 mm long, ovate and foliaceous, apically obtuse; South Africa Solanum umtuma Voronts. & S.Knapp
39b Calyx lobes on long-styled flowers 4–7 mm long, deltate or long-triangular apically acuminate; northern Africa and Cape Verde Islands 40
40a Calyx lobes on long-styled flowers 4–7 mm long, deltate, ca. 1/6 as long as the fruit at maturity; continental Africa north of the equator Solanum cerasiferum Dunal
40b Calyx lobes on long-styled flowers 6–7 mm long, long triangular, 1/2 to 1/3 as long as the fruit at maturity; Cape Verde Islands (Senegal?) Solanum rigidum Lam.
41a Prickles straight; corolla on long-styled flowers 1.8–2.5 cm in diameter; anthers ca. 4.5 mm long; Madagascar; Mauritius, Réunion Solanum insanum L.
41b Prickles curved or straight; corolla on long-styled flowers 2.5–4.5 cm in diameter; anthers 5–9 mm long; widespread 42
42a Leaves usually entire, sometimes lobed; trichomes on the abaxial leaf surface sessile or with stalks up to 0.1 mm long; fruits 1.5–3 cm diameter Solanum campylacanthum Hochst. ex A.Rich.
42b Leaves lobed; trichomes on the abaxial leaf surface with stalks up to 0.5(1) mm long; fruits 2.5–4.5 cm diameter 43
43a Leaves velvety red-brown adaxially; calyx lobes on long-styled flowers ovate to oblong, foliaceous, 7–10 mm long Solanum aureitomentosum Bitter
43b Leaves yellow-green to green-brown adaxially; calyx lobes on long-styled flowers deltate, usually not foliaceous, 2.5–6 mm long 44
44a Leaves concolorous to weakly discolorous, indumentum yellowish; leaves ca. 1.5 times longer than wide; young stems terete to angular; north-eastern Africa Solanum incanum L.
44b Leaves strongly discolorous, indumentum dirty greenish brown adaxially and whitish yellow abaxially; leaves 1.5–2.5 times longer than wide; young stems with somewhat raised longitudinal ridges; southern Africa Solanum lichtensteinii Willd.
45a Leaves on fertile branches with distinct lobes, at least some of the lobes longer than 1/4 of the distance from the midvein to the leaf edge 46
45b Leaves on fertile branches entire or subentire or with some shallow lobes no longer than 1/4 of the distance from the midvein to the leaf edge 89
46a Leaves more than 3 times longer than wide 47
46b Leaves 1–3 times longer than wide 49
47a Plant unarmed or prickles straight, orange to red; trichomes on the abaxial surfaces of the leaves with (9)12–14 rays Solanum elaeagnifolium Cav.
47b Plant densely armed with curved broad-based pale-yellow prickles; trichomes on the abaxial surfaces of the leaves, if present, with 0–8 rays 48
48a Anthers 2.5–3.2 mm long; trichomes anywhere on the plant with 0–4 rays; South Africa Solanum sodomaeodes Kuntze
48b Anthers 5–6.5 mm long; trichomes anywhere on the plant with 5–8 rays; north-eastern Africa Solanum glabratum Dunal
49a Leaves with at least some secondary lobing present 50
49b Leaves lobed once only 51
50a Flowers 3–7 per inflorescence, mauve to purple; anthers 5.5–7 mm long; South Africa Solanum rubetorum Dunal
50b Flowers 6–50 per inflorescence, white; anthers 9–10 mm long; invasive in South Africa and Kenya Solanum sisymbriifolium Lam.
51a No prickles visible anywhere on the plant 52
51b At least some prickles visible on the plant 57
52a Plant scandent or scrambling, sometimes erect; anthers (4)5–6.5 mm long; inland eastern Africa Solanum cyaneopurpureum De Wild.
52b Plant erect; anthers 2.3–5(8.5) mm long; widespread 53
53a Corolla 1.5–3 cm in diameter; mauve or purple; southern Africa, Indian Ocean islands 54
53b Corolla 0.9–1.5 cm in diameter; white (only occasionally pale violet); widespread on continent or cultivated 55
54a Fruiting pedicels deflexed, curved; anthers 3.5–5.2 mm long; South Africa and Namibia Solanum burchellii Dunal
54b Fruiting pedicels straight and spreading; anthers 4.5–8.5 mm long; Mauritius and Réunion Solanum violaceum Ortega
55a Inflorescences 2.5–6 cm long, with 5–22 flowers Solanum anguivi Lam.
55b Inflorescences 1–2.5 cm long, with 1–4(10) flowers 56
56a Leaf blades 5–18 cm long, petioles 1–4 cm long; plant cultivated for leaves or fruits, widespread Solanum aethiopicum L.
56b Leaf blades 3–8 cm long, petioles 0.5–1.5 cm long; wild plant in southern Africa Solanum catombelense Peyr.
57a Prickles on young stems predominantly curved 58
57b Prickles on young stems predominantly straight, sometimes straight and reflexed 70
58a Young prickles and indumentum red; scandent shrubs; Madagascar 59
58b Young prickles and indumentum yellowish, green or brown; erect or scandent shrubs; widespread (mainland Africa, rarely Madagascar, Indian Ocean Islands) 60
59a Young stems with a dense covering of long-stalked trichomes and prickles of different lengths; 1000–3000 m elevation Solanum myoxotrichum Baker
59b Young stems with a sparse or dense covering of sessile or short-stalked trichomes of uniform lengths; 0–1000 m elevation Solanum erythracanthum Dunal
60a Stem trichomes with stalks 0.1–0.4 mm long; anthers 6–10 mm long; coastal eastern Africa Solanum usaramense Dammer
60b Stem trichomes sessile or the stalks to 0.1 mm long; anthers 3–8.5 mm long; widespread 61
61a Plants of the Indian Ocean islands (Mauritius, Réunion, Aldabra) 62
61b Plants of continental Africa 63
62a Fruiting pedicels straight and spreading; corolla to 3 cm in diameter; petiole not winged from decurrent leaf base; Mauritius and Réunion Solanum violaceum Ortega
62b Fruiting pedicels curved and deflexed; corolla to 2 cm in diameter; petiole slightly winged from decurrent leaf base; Aldabra (Seychelles) Solanum aldabrense C.H.Wright
63a Calyx in flower 7–9 mm long, apically caudate; calyx in fruit 10–12 mm long; trichomes with midpoints much longer that the rays; Tanzanian highlands, rare Solanum inaequiradians Bitter
63b Calyx in flower 2–6 mm long, apically acute to acuminate or rarely caudate; calyx in fruit less than 10 mm long; trichomes with the midpoints short than or equal to the rays; widespread 64
64a Plant always erect; leaves discolorous; corolla 0.8–1.5 cm in diameter, lobed for 1/2–2/3(3/4) of the way to the base 65
64b Plant often scandent or semi-scandent; leaves usually concolorous; corolla (1)1.5–2.5 cm in diameter, lobed for 2/3 of the way to the base or more 66
65b Inflorescences 2.5–6 cm long, with 5–22 flowers; polymorphic weed across highland areas of Africa and Madagascar Solanum anguivi Lam.
65a Inflorescences 1–2.5 cm long, with 1–4 flowers; southern Africa Solanum catombelense Peyr.
66a Prickles 3–5 mm long; leaf blades 1.5–2.5(9) cm long, leaf base narrow-cuneate to attenuate; South Africa and Namibia Solanum capense L.
66b Prickles 1–4(7) mm long. Leaf blades (1)2.5–14 cm long, leaf base cuneate to truncate; widespread 67
67a Calyx 2–4 mm long in flower 68
67b Calyx 4–6 mm long in flower 69
68a Prickles on young stems 1.5–2(3) mm long; leaves 2.5–5.5 cm long; seeds 2.5–3.5 mm long; inland eastern Africa Solanum cyaneopurpureum De Wild.
68b Prickles on young stems 2–4 mm long. Leaves 3–14 cm long; seeds 1.8–2.5 mm long; coastal eastern Africa Solanum zanzibarense Vatke
69a Leaves drying yellow-green; petiole 1/4–1/3 of the leaf length; eastern and north-eastern Africa Solanum hastifolium Hochst. ex Dunal
69b Leaves drying dark red-brown; petiole 1/3–1/2 of the leaf length; southern Africa Solanum torreanum A.E.Gonç.
70a Inflorescence with more than 10 flowers 71
70b Inflorescence with 10 or fewer flowers 74
71a Leaves 1–4(6) cm long; corolla 1.3–2.4 cm in diameter; seeds almost black; north of the equator Solanum forskalii Dunal
71b Leaves (5)7–25 cm long; corolla 0.7–1.5 cm in diameter; seeds yellow to orange-brown; widespread 72
72a Inflorescences 1–2.5 cm long, peduncle 0–2 mm long; trichomes on the young stems with (5)8–20 rays; western Africa Solanum anomalum Thonn.
72b Inflorescences 2.5–8 cm long, peduncle 2–30 mm long; trichomes on the young stems with 6–8 rays; widespread 73
73a Inflorescences branched many times (more than once); Kenya and Tanzania Solanum usambarense Bitter
73b Inflorescences unbranched or forked; widespread Solanum anguivi Lam.
74a Young prickles almost filiform and easily bendable like bristles, with no firm prickles anywhere on the plant; eastern African savannah Solanum setaceum Dammer
74b Young prickles sturdy when touched; widespread 75
75a Calyx lobes oblong, foliaceous, apically obtuse; lowland eastern Africa, rare Solanum lamprocarpum Bitter
75b Calyx lobes deltate, sometimes long-ovate or narrow-oblong, not clearly foliaceous, apically acute to acuminate; widespread 76
76a Calyx 7–12 mm long in flower 77
76b Calyx 2–7 mm long in flower 80
77a Prickles on young branches 8–16 mm long; leaves elliptic; Ethiopian highlands Solanum macracanthum A.Rich.
77b Prickles on young branches 2–7 mm long; leaves ovate; Tanzania, South Africa and Madagascar 78
78a Corolla lobed for 3/4 of the way to the base or more; trichomes on the young stems with midpoints (0.5)1.5–2.5(3) mm long; Tanzanian highlands Solanum inaequiradians Bitter
78b Corolla lobed for 1/2–2/3 of the way to the base; trichomes on the young stems with midpoints 0.15–5 mm long; South Africa and Madagascar 79
79a Young stems with a dense covering of long-stalked trichomes and prickles of different lengths; Madagascar Solanum myoxotrichum Baker
79b Young stems with no bristles, only prickles and trichomes of uniform length; South Africa Solanum tomentosum L.
80a Young prickles and indumentum red; pedicels (1)1.5–4 cm long; Madagascar 81
80b Young prickles and indumentum pale yellow to brown or purple, never red; pedicels 0.2–1(1.4) cm long; mainland Africa, rarely in Madagascar 82
81a Young stems with a dense covering of long-stalked trichomes and prickles of different lengths; 1000–3000 m elevation Solanum myoxotrichum Baker
81b Young stems with a sparse or dense covering of sessile or short-stalked trichomes of uniform lengths; 0–1000 m elevation Solanum erythracanthum Dunal
82a Corolla lobed for 3/4 of the way to the base or deeper; plants scrambling or climbing, sometimes erect 83
82a Corolla lobed for 1/2–2/3 of the way to the base; plants erect, sometimes scandent 86
83a Prickles on young stems 2–4 mm long; eastern African coastal areas Solanum zanzibarense Vatke
83b Prickles on young stems (3)4–13 mm long; arid environments across continental Africa 84
84a Prickles reflexed; seeds nearly black Solanum forskalii Dunal
84b Prickles perpendicular to the stem; seeds pale yellow to orange-brown 85
85a Leaves 1–2 times longer than wide; leaf lobes to 2/3 of the distance to the midvein; leaves concolorous to strongly discolorous; north-eastern Africa Solanum adoense Hochst. ex A. Rich.
85b Leaves 1.5–3 times longer than wide; leaf lobes to 1/2 of the distance to the midvein; leaves concolorous; South Africa Solanum humile Dunal
86a Petiole 1/3–2/3 as long as the leaf blade; South Africa Solanum tomentosum L.
86b Petiole 1/6–1/3 as long as the leaf blade; widespread 87
87a Leaf blades (5)11–25 cm long; inflorescence with 5–22 flowers; common variable highland weed widespread across Africa Solanum anguivi Lam.
87b Leaf blades 1.7–9 cm long; inflorescence with 1–6 flowers; southern Africa 88
88a Leaves elliptic; corolla 1.5–2.2 cm in diameter, mauve to purple Solanum burchellii Dunal
88b Leaves ovate, sometimes oblong; corolla 0.9–1.3 cm in diameter, usually white Solanum catombelense Peyr.
89a At least some inflorescences branched several to many times; inflorescence with (10)20–150 flowers; erect shrubs to small trees 90
89b Inflorescences unbranched or forked; inflorescence with 1–10(20) flowers; scrambling, scandent or erect shrubs 98
90a Plants with at least some visible prickles or bristles 91
90b Plants with no prickles or bristles visible 95
91a Young stems with soft or thin bristles 92
91b Young stems with firm deltate prickles 93
92a Stem bristles soft and white, 0.4–0.7 mm wide at base; leaves ca. 2 times longer than wide; 1500 -1800 m elevation; Tanzania Solanum schliebenii Werderm.
92b Stem bristles erect purple-black or brown, 0.2–0.4 mm wide at base; leaves 2.5–3.5 times longer than wide; 1800–2600 m elevation; eastern Africa Solanum schumannianum Dammer
93a Leaf blades 12–40 cm long, whitish grey underneath with trichomes, falling as white powder when touched; inflorescences with 30–150 flowers; anthers 2.5–3 mm long Solanum giganteum Jacq.
93b Leaf blades 4–10(16) cm long, yellow-green, brown or rarely whitish grey underneath, trichomes not falling when touched; inflorescences with 10–30 flowers; anthers 3.5–6 mm long 94
94a Leaf base cuneate to acuminate; anthers 3.5–4 mm long; stem trichomes with midpoints 0.4–1(2) mm long; Democratic Republic of the Congo, Rwanda, Uganda, Tanzania; rare Solanum wittei Robyns
94b Leaf base rounded, rarely cuneate; anthers 4–6 mm long; stem trichomes with midpoints 0.05–0.2 mm long; widespread Solanum tettense Klotzsch
95a Leaves elliptic, with 8–12 pairs of primary veins, 2.5–3.5 times longer than wide Solanum schumannianum Dammer
95b Leaves ovate, sometimes elliptic, with 4–8 pairs of primary veins, 1.5–2.5(3) times longer than wide 96
96a Leaves concolorous; calyx lobes 2–4(5) mm long, long-acuminate; Sudan, Eritrea, Ethiopia, Somalia, 1500–2800 m elevation Solanum schimperianum Hochst. ex A.Rich.
96b Leaves discolorous; calyx lobes 1–2 mm long, obtuse to acute, sometimes acuminate; southern Ethiopia, Somalia and further south, 650–1900 m elevation 97
97a Leaf base cuneate to acuminate; anthers 3.5–4 mm long; stem trichomes with midpoints 0.4–1(2) mm long; Democratic Republic of the Congo, Rwanda, Uganda, Tanzania; rare Solanum wittei Robyns
97b Leaf base rounded, rarely cuneate; anthers 4–6 mm long; stem trichomes with midpoints 0.05–0.2 mm long; widespread, common Solanum tettense Klotzsch
98a Plants with no prickles visible 99
98b Plants with at least some visible prickles. 109
99a Leaves 3–8 times longer than wide, narrow-elliptic or lanceolate, rarely narrow-ovate 100
99b Leaves 1–3 times longer than wide, orbicular, ovate, obovate, elliptic or oblong 101
100a Corolla 0.9–1.5 cm in diameter; trichomes on young stems with ca. 8 rays; native plant in eastern and north-eastern Africa, black cotton soils Solanum lanzae J.-P.LeBrun & Stork
100b Corolla 2.5–3(5) cm in diameter; trichomes on young stems with 10–14(16) rays; weed in southern Africa and Mediterranean Solanum elaeagnifolium Cav.
101a Leaves less than 1.5 times longer than wide, orbicular, ovate or obovate; arid north-eastern Africa 102
101b Leaves more than 1.5 times longer than wide, ovate, elliptic or oblong; widespread 103
102a Erect shrub to small tree 1.5–4 m tall; leaves and flowers readily deciduous, so stems often bare; seeds orange-brown Solanum jubae Bitter
102a Scandent to erect shrub up to 1 m tall; leaves and flowers not readily deciduous, stems not bare; seeds dark brown to almost black Solanum cordatum Forssk.
103a Leaf base attenuate; corolla lobed for ca. 3/4 of the way to the base; trichomes on the young stems with 10–20 rays 104
103a Leaf base cuneate, rounded or truncate, rarely attenuate; corolla lobed for 1/2–2/3 of the way to the base; trichomes on the young stems with 6–9(12) rays 105
104a Petioles 1/3–2/3 as long as the adult leaves; flowers 4–8 per inflorescence; seeds 2.8–3.5 mm long; Angola Solanum pauperum C.H.Wright
104b Petioles 1/6–1/4 as long as the adult leaves; flowers 8–15 per inflorescence; seeds 3.6–4.8 mm long; eastern and south-eastern Africa Solanum goetzei Dammer
105a Calyx lobes 5–10 mm long in flower, foliaceous, ovate to elliptic; leaf apex rounded, sometimes obtuse; arid north-eastern Africa Solanum pampaninii Chiov.
105b Calyx lobes 1–4.5 mm long in flower, not clearly foliaceous, deltate; leaf apex acute or obtuse, sometimes rounded; widespread 106
106a Scandent shrub; inflorescences 3.5–7 cm long; young stems with stalked trichomes, the stalks 0.1–0.4 mm long; eastern African highlands Solanum stipitatostellatum Dammer
106b Erect herb or shrub; inflorescences 1–3.5 cm long; young stems with sessile or stalked trichomes, the stalks up to 0.15 mm long; widespread 107
107a Fruit (1)1.5–2.5(5) cm in diameter; plant cultivated for leaves or fruits; widespread and common in western and eastern Africa Solanum aethiopicum L.
107b Fruit (0.7)0.75–1.1 cm in diameter; wild plant in southern Africa 108
108a Leaves elliptic; corolla 1.5–2.2 cm in diameter, mauve to purple Solanum burchellii Dunal
108b Leaves ovate, sometimes oblong; corolla 0.9–1.3 cm in diameter, usually white Solanum catombelense Peyr.
109a Prickles on young stems predominantly curved 110
109b Prickles on young stems predominantly straight, sometimes straight and reflexed 125
110a Most leaves on reproductive branches less than two times longer than wide 111
110b Most leaves on reproductive branches two times longer than wide or longer 115
111a Corolla lobed for ca. 3/4 of the way to the base or deeper; seeds dark brown to almost black; continental Africa north of the equator 112
111b Corolla lobed for ca. 2/3 of the way to the base; seeds yellow to orange-brown; continental Africa south of the equator 113
112a Inflorescences with 1(2) flowers; trichomes on young stem with 12–18 rays Solanum cordatum Forssk.
112b Inflorescences with (1)2–20 flowers; trichomes on young stem with 6–10 rays Solanum forskalii Dunal
113a Leaves drying yellowish green; anthers 3–4 mm long; southern Africa Solanum litoraneum A.E.Gonç.
113b Leaves drying reddish brown; anthers (4.5)5.5–8 mm long; Madagascar 114
114a Young stems with a dense covering of long-stalked trichomes and prickles of different lengths; 1000–3000 m elevation Solanum myoxotrichum Baker
114b Young stems with a sparse or dense covering of sessile or short-stalked trichomes of uniform lengths; 0–1000 m elevation Solanum erythracanthum Dunal
115a Plant erect, 0.4–1.5 m tall; corolla 0.9–1.4 cm in diameter; anthers 2.5–3.5 mm long 116
115b Plant scandent, sometimes erect; corolla (1.2)1.5–3 cm in diameter; anthers 4–8 mm long 117
116a Inflorescence 3–4(6) cm long; trichomes on abaxial surfaces of the leaves with stalks 0.15–0.4 mm long; eastern Africa Solanum mauense Bitter
116b Inflorescence 1–2.5 cm long; trichomes on abaxial surfaces of the leaves with stalks 0–0.15 mm long; southern Africa Solanum catombelense Peyr.
117a Calyx 7–9 mm long at anthesis, the lobes caudate; trichomes on young stems with midpoints (0.5)1.5–2.5(3) mm long; Tanzanian highlands Solanum inaequiradians Bitter
117b Calyx 2–6 mm long at anthesis, the lobes acute to acuminate; trichomes on young stems with midpoints 0–1.5 mm long; widespread 118
118a Leaves 3–6 times longer than wide, the bases attenuate; arid eastern and north-eastern Africa Solanum glabratum Dunal
118b Leaves 2–3 times longer than wide, the bases cuneate to cordate; eastern Africa and Madagascar 119
119a Corolla (1.8)2–3 cm in diameter; anthers (5.5)6–10 mm long 120
119b Corolla 1–2(2.4) cm in diameter; anthers 4–6(7) mm long 122
120a Inflorescences with 1–2(5) flowers; young stems with trichomes sessile or stalked, the stalks up to 0.2 mm long; Madagascar Solanum erythracanthum Dunal
120b Inflorescences with 3–10 flowers; young stems with trichomes always stalked, the stalks 0.1–0.4 mm long; eastern Africa 121
121a Leaves 3–8 cm long, densely stellate-pubescent on both sides; eastern African coasts Solanum usaramense Dammer
121b Leaves 6–13 cm long, adaxially glabrescent; eastern African mountains Solanum stipitatostellatum Dammer
122a Leaves apically rounded, with thick-stalked trichomes on the adaxial surface; inflorescence with 1–2(3) flowers; eastern Africa Solanum taitense Vatke
122a Leaves apically acute to obtuse, sometimes rounded, without thick-stalked trichomes on the adaxial surface; inflorescence with (1)2–20 flowers 123
123a Leaves with 2–3 pairs of primary veins; seeds dark brown to almost black; continental Africa north of the equator Solanum forskalii Dunal
123b Leaves with 4–6 pairs of primary veins; seeds yellow to orange-brown; continental Africa south of the equator or near the equator 124
124a Prickles usually under 2 mm long; leaves 2.5–5.5 cm long; trichomes on the leaves and stems with stalks ca. 0.1 mm long; inland eastern Africa Solanum cyaneopurpureum De Wild.
124b Prickles over 2 mm long; leaves 3–14 cm long; trichomes on the leaves and stems sessile or with stalks under 0.1 mm long; coastal eastern Africa Solanum zanzibarense Vatke
125a Leaves more than two times longer than wide 126
125b Leaves less than two times longer than wide 130
126a Corolla 2.5–3(5) cm in diameter; anthers 6–10 mm long; invasive in southern Africa and around the Mediterranean Solanum elaeagnifolium Cav.
126b Corolla 0.9–2.3 cm in diameter; anthers 2.5–6 mm long; Ethiopia, Tanzania or further south 127
127a Prickles on young stems 8–16 mm long; calyx 7–12 mm long at anthesis; Ethiopia Solanum macracanthum A.Rich.
127b Prickles on young stems 1–6 mm long; calyx 2.5–7 mm long at anthesis; Tanzania or further south 128
128a Plant scrambling shrub; leaves almost glabrous, trichomes on the leaves with up to 4 rays; Tanzanian coastal forest, rare (possibly extinct) Solanum ruvu Voronts.
128b Plant erect; leaves stellate-pubescent, trichomes on the abaxial sides of the leaves with 17–15 rays; southern Africa 129
129a Leaves elliptic; corolla 1.5–2.2 cm in diameter, mauve to purple Solanum burchellii Dunal
129b Leaves ovate, sometimes oblong; corolla 0.9–1.3 cm in diameter, usually white Solanum catombelense Peyr.
130a Leaves on reproductive branches less than 2 cm long 131
130b Leaves on reproductive branches more than 2 cm long 134
131a Leaves and flowers predominantly on short shoots, few on main stems; corolla lobed for 1/2–2/3 of the way to the base; seeds yellow to orange-brown; southern Madagascar 132
131b Leaves and flowers predominantly on main stems, few on short shoots; corolla lobed for ca. 3/4 of the way to the base; seeds dark brown to almost black; continental Africa north of the equator 133
132a Calyx lobes fused in fruit, ca. 10 mm long, fully covering the mature fruit; leaves ovate Solanum toliaraea D’Arcy & Rakot.
132b Calyx lobes free in fruit, 4–5 mm long, the mature fruit at least partly exposed; leaves orbicular, elliptic or ovate Solanum batoides D’Arcy & Rakot.
133a Inflorescences with 1(2) flowers; trichomes on young stem with 12–18 rays Solanum cordatum Forssk.
133b Inflorescences with (1)2–20 flowers; trichomes on young stem with 6–10 rays Solanum forskalii Dunal
134a Leaves elliptic 135
134a Leaves ovate 136
135a Leaves drying yellow-green; anthers 3.5–5.2 mm long; southern Africa Solanum burchellii Dunal
135b Leaves drying reddish brown; anthers 5.5–8 mm long; Madagascar Solanum erythracanthum Dunal
136a Anthers 3.2–3.5 mm long; southern Africa Solanum tomentosum L.
136b Anthers 4.5–8 mm long; widespread 137
137a Calyx lobes 3–7 mm long at anthesis 138
137b Calyx lobes 0.5–3 mm long at anthesis 139
138a Leaves yellow-green; trichomes on the abaxial sides of the leaves with midpoints 1–2 mm long; Tanzania Solanum inaequiradians Bitter
138b Leaves reddish; trichomes on the abaxial sides of the leaves with midpoints to 0.5 mm long; Madagascar Solanum myoxotrichum Baker
139a Leaves 6–13 cm long; prickles on young stems 1–2 mm long; highland eastern Africa Solanum stipitatostellatum Dammer
139b Leaves 1–5(6) cm long; prickles on young stems 2–10 mm long; continental Africa, north of the equator or Madagascar 140
140a Pedicels 0.2–1 mm long; seeds almost black; continental Africa, north of the equator Solanum forskalii Dunal
140b Pedicels 1.5–2(2.5) cm long; seeds dull yellow to orange-brown; Madagascar Solanum erythracanthum Dunal

Acknowledgements

We thank the curators of the herbaria cited in the Appendix 2 for permission to examine specimens in their care; Michael Gilbert for assisting with key reformatting; Sarah Ficinski, Morvah George, Juana de Egea, Samantha Murphy, Xavier Aubriot and David Spooner all greatly helped in the databasing of specimens and in assessing distributions; comments from Leandro Giacomin, Roy Gereau and Gloria E. Barboza greatly improved the manuscript; much of the field and herbarium work was funded by the National Science Foundation Planetary Biodiversity Inventory program grant “PBI Solanum – a worldwide treatment” (DEB-0316614) to SK; other herbarium visits were funded by the SYNTHESYS Project http://www.synthesys.info/ which was financed by European Community Research Infrastructure Actions under the FP6 and FP7 “Structuring the European Research Area” Programme; Natural History Museum Special Funds awards; and the Royal Society through travel grants.

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