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Corresponding author: Gabriel K. Ameka ( gameka@ug.edu.gh ) Academic editor: Sandy Knapp
© 2019 Felix Kuetegue, Bonaventure Sonké, Gabriel K. Ameka.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Kuetegue F, Sonké B, Ameka GK (2019) A checklist of rheophytes of Cameroon. PhytoKeys 121: 81-131. https://doi.org/10.3897/phytokeys.121.29924
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Rivers in Cameroon were surveyed to collect and document rheophytic plants. Rheophytes are the dominant aquatic macrophytes in tropical river systems, where they are adapted to extreme environments of rushing water (e.g., river rapids, waterfalls and flash floods). Rheophytic plants are useful indicators of river health. However, their habitats are threatened by human activities such as agriculture, plantation development, alluvial mining and dam construction, particularly in tropical countries. In this survey we documented 66 rheophytic species in 29 genera and 16 families. Two ferns, 8 monocotyledons and 56 dicotyledons were listed. Apart from the Podostemaceae family in which all species are rheophytic, the other 15 families have few species which are rheophytic. Five of these families have up to four species and the remaining 10 have only one member as a rheophytic species. The conservation status of each species is assessed and discussed. This work urges botanists, conservationists, and policy makers to do more to protect the habitats of rheophytes and put in place strategies and action plans for the conservation of this important biological group.
Cameroon, conservation, distribution, inventory, Rheophyte diversity
Rheophyte, a term coined by van Steenis in 1932 (
Twenty-one rheophytic species, excluding the Podostemaceae, were recognized in tropical Africa, in a worldwide census of rheophytes by
A survey to document and study the rheophytes of Cameroon is important for a number of reasons: (i) rheophytes are poorly known in tropical Africa, including Cameroon, compared to South East Asia and South America, according to
The survey to enumerate and document the rheophytes of Cameroon was conducted from 2010 to 2014; and the rheophytic species encountered are reported here. It is hoped that this work will stimulate further research on rheophytes across the rest of tropical Africa. We draw attention to the urgent need to stop the destruction of habitats of rheophytes and rather map out strategies and action plans for the conservation of this important biological group.
A survey of rheophytes was carried out in Cameroon, situated between 2°–13°N and 9°–16°E (Fig.
The central and western parts of Cameroon are dominated by high mountains and plateaus (
In documenting the rheophytes of Cameroon, several rivers (Fig.
Voucher specimens in YA were also consulted for rheophytes already collected from Cameroon. The Flora of West Tropical Africa (
Distribution maps of rheophytes of Cameroon were done using georeferenced specimen data derived from specimen labels or available literature, and our own field surveys. The conservation status of each species was assessed by calculating the extent of occurrence (EOO) and the area of occupancy (AOO) in Cameroon using GeoCAT (Geospatial Conservation Assessment tool;
The list of rheophytes identified during the study is presented as a checklist organized by families, and each entry consists of the following:
The checklist of rheophytes of Cameroon contains 16 families and 66 species. The rheophytic species listed may be placed in two categories: in the first category are families in which few species are rheophytic and in the second category are families in which all species are rheophytic. The former category has 15 families, 17 genera, and 23 species, while the latter category contains only the Podostemaceae family with 12 genera and 43 species.
Acrostichum fluviatile Hook., Sp. Fil. 5: 274 (1864)
Acrostichum phanerodictyon Baker, Bol. Soc. Brot. 4: 156, t. 2 (1886)
Leptochilus fluviatilis (Hook.) C.Chr., Index Filic. 10, 385 (1905)
Equatorial Guinea, Fernando Po (Bioko), G. Mann 442 (K, K000435773).
Herbaceous, rhizome creeping, with opaque, castaneous scales; fixed to rocks by roots; sterile fronds lanceolate, up to 85 cm long; fertile fronds up to 90 cm long with sporangia on lower surface.
15 km southeast of Zingui, 14 Mar 1968, R. Letouzey 9031 (YA); near Ababendoman, 65 km southeast of Ebolowa, 00 Jan 1970, R. Letouzey 9958 (YA); Muanenguba Mts. northeast of Nkongsamba, 4°58'N, 9°53'E, 11 Dec 1971, A. J. M. Leeuwenberg 8848 (YA).
Rocky riverbeds and streams, and rocky borders of streams and rivers; in evergreen rainforest.
Cameroon (Fig.
Bolbitis fluviatilis is not listed on http://www.iucnredlist.org nor in
2 Bolbitis fluviatilis (Hook.) Ching 3 Bolbitis heudelotii (Bory ex Fée) Alston 4 Lepidagathis alopecuroides R.Br. ex Griseb. 5 Achyranthes talbotii Hutch & Daziel 6 Crinum natans Baker 7 Kanahia laniflora (Forssk.) R.Br. 8 Anubias barteri Schott 9 Cyperus rheophyticus Lye 10 Cyperus tonkinensis var. baikiei (C.B.Clarke ex Kuk) S.S.Hooper.
Gymnopteris heudelotii Bory ex Fée, Mém. Foug., 2. Hist. Acrostich. 84: 45, t. 45 (1845)
Leptochilus heudelotii (Bory ex Fée) C.Chr., Index Filic. 11, 385 (1905)
Guinea Conakry, Fouta Djallon, in herb Bory, Heudelot 803 (holotype: P).
Herbaceous, rhizome thick with dark brown scales and creeping on rocks; numerous roots; sterile fronds 30–80 cm long, linear to elliptical; fertile fronds 25–100 cm, long, linear, abaxial surface with sporangia.
Pangar River, at Tapare (Dang Assoura), 5°22'N, 13°31'E, 11 Feb 1961, R. Letouzey 3452 (YA); Maan, 24 km southeast of Nyabesan, 00 Feb 1963, J. & A. Raynal 10264 (YA); East of Kribi on Kienke River, 2°56'N, 9°55'E, 05 Apr 1969, J. J. Bos 4282 (YA); Limbe at Limbe River, 4°2'N, 9°12'E, 13 Jan 2011, F. Kuetegue 412, 414 (YA).
Riverbeds of perennial streams; edge of waterfalls; seasonally flooded in swift-flowing rivers or streams, able to withstand spate; in rainforest.
Widespread in tropical Africa. Angola, Benin, Cameroon (Fig.
Bolbitis heudelotii is not listed on http://www.iucnredlist.org nor in
Adenosma chenopodiifolia (Poir.) Spreng., Syst. Veg. ed. 16, 2: 829 (1825)
Aetheilema alopecuroidea (Vahl) Spreng., Syst. Veg. 2: 826 (1825)
Ruellia alopecuroidea Vahl, Eclog. Amer. 2: 49 (1798)
Ruellia chenopodiifolia Poir., Encycl. 6(1): 339 (1804)
Teliostachya alopecuroidea Nees, Prodr. 11: 263 (1847)
Sierra Leone, by Scaries River, 1891, G. F. Scott Elliot 4533 (K, K000529239).
Herb, slender, flexible, decumbent and branching stems, with lanceolate leaves 5.0–6.5 × 0.4–0.6 cm; strong fibrous root system; pink or purplish flowers.
40 km northwest of Moloundou on Dja River, 18 Mar 1973, R. Letouzey 12132 (YA); Ndian 50 m on bank of Mana River, 4°58'N, 8°51'E, 09 Dec 1983, D. W. Thomas 2659 (YA); Mundemba on Mana River, 11 Jan 1998, M. Cheek 8850 (YA).
Rocky and sandy riverbeds or on the banks of rivers and streams; in rainforest.
Benin, Cameroon (Fig.
Lepidagathis alopecuroides is not listed on http://www.iucnredlist.org nor in
Nigeria, Keay, R. W. J. FHIFHI 28284 (holotype: K, K000243718).
Perennial herb with soft woody stem to 45 cm tall; strong fibrous root system; lanceolate leaves 2–4 × 1–1.5 cm.
Near Ndokman II, approximately 8 km east of Yingui or 35 km east of Yabassi, 4°34'N, 10°10'E, 00 Jan 1972, R. Letouzey 10938 (YA); bank of Nkam River, near Sake, 3 km southwest of Nkondjok, 4°77'N, 10°17'E, 07 Jan 1972, R. Letouzey 11163 (YA); Mumgo River, Kumba-Loum road, 2°49'N, 9°33'E, 00 Jan 1981, Breyne 5062 (YA); Kombon at the bank of Kombon River, 4°59'N, 9°26'E, 23 Mar 2011, F. Kuetegue 316 (YA).
Sandy and rocky riverbeds or up to flood level on the bank, in rainforest.
Cameroon (Fig.
Achyranthes talbotii was assessed by
Crinum natans subsp. inundatum Kwembeya & Nordal; Phylogeny Speciation Biogeogr. Crinum Chlorophytum 3:16 (2008)
Equatorial Guinea, Fernando Po (Bioko), G. Mann 1416 (lectotype: K; isotype: P).
Herb with small bulb, very strong root system; leaves crinkled, submerged and floating, 140 × 2.2 cm; flowers large, borne above the water.
15 km north of Edea, near the bridge, 22 Jan 1969, J. J. Bos 1969 (YA); Balondo, 25 km southwest of Nkongsamba, 4°43'N, 9°51'E, 00 Mar 1976, R. Letouzey 14441 (YA); Soo village, near bridge on Soo River, 3°20'N, 11°30'E, 06 Apr 1977, Inger Nordal 906 (YA); Diongo (Kumba – Nguti road) on bank of Mengue River, 4°45'N, 9°29'E, 21 Mar 2011, F. Kuetegue 507 (YA).
Bed of swift-flowing perennial streams and rivers, submerged permanently, strong fibrous root system, in sand, silt or gravel riverbeds; in evergreen rainforest.
Cameroon (Fig.
Crinum natans was not listed on http://www.iucnredlist.org nor assessed by
Asclepias coarctata S.More, J. Bot. 46: 297 (1908)
Asclepias fluviatilis A.Chev., Bull. Soc. Bot. France 61(8): 271 (1917)
Asclepias laniflora Forssk., Fl. Aegypt.-Arab. 51 (1775)
Asclepias rivalis S.More, J. Bot. 52: 337 (1914)
Gomphocarpus glaberrimus Oliv., Trans. Linn. Soc. London 29(3): 110 (1875)
Kanahia consimilis N.E.Br., Fl. Trop. Afr. 4(1.2): 298 (1902)
Kanahia glaberrima (Oliv.) N.E.Br., Fl. Trop. Afr. 4(1.2): 297 (1902)
Cameroon, G. L. Bates 322 (lectotype: K, K000234855).
Erect woody shrub, up to 2 m high; leaves linear-lanceolate 4–15 × 0.5–1.0 cm, glabrous; inflorescence axillary, one per node between leaf bases; flowers creamy white.
Dibombe River, 4°41'N, 9°48'E, 16 Mar 1965, A. J. M. Leeuwenberg 9708 (YA); bank of UVE River, 20 km northwest of Kumba, 20 Mar 1976, R. Letouzey 38378 (YA); Mundemba, on Ndian (Mana) River, 4°58'N, 8°51'E, 09 Dec 1983, D. W. Thomas 2656 (YA); Ntale, bank and bed of Mbier River, 10 Dec 2010, F. Kuetegue 272, 273 (YA).
Rocky or sandy riverbeds and by seasonal rivers, in wet evergreen and semi-deciduous rainforests to deserts.
Benin, Cameroon (Fig.
Kanahia laniflora was not assessed by
Equatorial Guinea, Fernando Po (Bioko), Barter 2045 (K).
Hardy herb with thick creeping rhizome, prostrate; strongly rooted; green, lush, narrow shaped leaves 7–30 × 3–15 cm.
Fenda, 60 km southeast of Kribi, 22 Jan 1962, R. Letouzey 4120 (YA); Nyon River, 49 km southwest of Eseka, 12 Mar 1965, A. J. M. Leeuwenberg 5136 (YA); road from Ebone to Yabassi at mile 10, 27 Dec 1967, P. Bamps 1636 (YA), Nguti-Kombon, bank of Kombon River, 5°13'N, 9°33'E, 13 Dec 2010, F. Kuetegue 239 (YA).
Rocky beds of swift-flowing streams and rivers, or wet shrubby and bushy bank of rivers and streams; in rainforest.
Cameroon (Fig.
Anubias barteri is listed on http://www.iucnredlist.org as Least Concern (LC) in central Africa in 2007 by
Cameroon, South West Division, Kupe-Muanenguba Division, Muambong, bank of Chide River, 3°58'N, 9°41'E, 02 Aug 1998, J.-M. Onana 585, (holotype: K; isotype: YA).
Perennial herb, 30–50 cm high; deeply rooted; inflorescence terminal, with involucre bracts.
Kodmin, beside a stream, 4°59'N, 9°42'E, 21 Nov 1998, M. Etuge 406 (YA).
Forest streams and rivers, submerged during wet season.
Cameroon (Fig.
Cyperus rheophyticus is listed on http://www.iucnredlist.org as Vulnerable in 2017 (
Cyperus baikiei C.B.Clarke, Consp. Fl. Afr. [T.A. Durand & H. Schinz] 5: 550 (1894)
Cyperus kottensis Chem. Arch. Bot., Caen iv. Mem. No. 7, 23 (1931)
Vietnam, Tonkin, Tu-Phap, 12 Apr 1888, Balansa 2831 (K).
Herb, about 12 cm high, with hard tubers, connected by dark brown rhizome; stems dark brown and shiny; inflorescence spikelets, glumes brown.
62 km southeast of Bafia, on Sanaga River, 4°75'N, 11°22'E, 27 Mar 1963, J. & A. Raynal 10538 (YA); Sanaga River, bridge near Nkong Njok, 4°10'N, 11°01'E, 12 Mar 1978, J. Lowe 3483 (YA); Bongossi Research Plot of the National Herbarium of Cameroon, bank of Sanaga River, 4°22'N, 11°16'E, 29 Mar 1987, L. Ake Asse 1859 (YA); near Nguti, Mbombe on Loa River, 29 May 2011, F. Kuetegue, 498 (YA).
Sandy bars or beds of streams and rivers.
Benin, Cameroon (Fig.
Cyperus tonkinensis var. baikiei is not listed on http://www.iucnredlist.org nor assessed by
Pycreus cataractarum C.B.Clarke, Bot. Jahrb. Syst. 38(2): 132 (1906)
Cameroon, Bipindi, 1899, G. Zenker 1935 (syntype: BR, K, P, P00573020, WAG).
Tufted, grass-like leaves forming high sods (up to 30 cm thick cushions); roots forming large fibrous tussocks; stems smoothly glossy; leaves linear, green to dark green; spikelets greenish-white; glumes with a green midrib.
27 km from Kribi in Kienké River, 2°52'N, 10°7'E, 27 Jan 1970, J. J. Bos 6168 (YA); Mpoume waterfalls on Nyong River at Makak, 3°28'N, 11°01'E, 01 Jan 1978, J. Lowe 3420 (YA); near Akonetyè village, Mboro waterfalls, 15 Jan 1978, A. Koufani 20 (YA).
Banks, edges and beds of streams and rivers; in rainforest.
Cameroon (Fig.
Cyperus cataractarum is not listed on http://www.iucnredlist.org nor assessed by
11 Cyperus cataractarum K.Schum ex Engl. 12 Plectranthus cataractarum B.J.Pollard 13 Calvoa stenophylla Jacq.-Fél. 14 Eugenia dusenii Engl. 15 Biophytum talbotii (Baker f.) Hutch. & Dalziel 16 Biophytum zenkeri Guillaumin 17 Pandanus satabiei Huynh 18 Eragrostis barteri C.E.Hubb. 19 Ixora euosmia K.Schum.
Cameroon: Hunters path to Lake Njonji at side of seasonal watercourse, M. Cheek 5563 (holotype: K; isotypes: MA, MO, SCA, WAG, YA).
Annual or perennial herb growing to 60 cm tall; stems decumbent to ascending, sub-woody at the base; leaves slightly fleshy, 20–45(-70) × 5–20(-25) mm, 2–2.5 times as long as broad; inflorescence terminal.
Etinde, Njonji, footpath from Cameroon Development Corporation oil palm plantations to the summit, 24 Nov 1993, Williams 52 (K, SCA, WAG, YA); Bakossi Mts: Chutes de ‘Ile Ndip Medschang, 21 Nov 1998, Satabie 1109 (K, K000051130).
Invariably growing in spray zone of waterfalls, on wet rocks or on river banks, up to flood level, of swift-running water; lowland or submontane evergreen forest, 300–1450 m alt.
Cameroon (Fig.
Plectranthus cataractarum is listed on http://www.iucnredlist.org. The species was assessed as Vulnerable (
Cameroon, 10 km Southeast of Zingui, 16 Mar 1968, R. Letouzey 9083. (Holotype: P; isotype: YA).
Small herb, about 20 cm high; stem flexible; roots spreading and fibrous; leaves narrow-lanceolate 4–6 × 0.2–0.5 cm; flowers terminal, pink.
Minsomo River, 10 km southeast of Zingui, 2°56'N, 9°54'E, 16 Mar 1968, R. Letouzey 9083 (YA).
Rocks on bed of Minsomo River.
Cameroon (Fig.
Calvoa stenophylla is listed on http://www.iucnredlist.org as Endangered (
Myrtus dusenii Kuntze, Deutsche Bot. Monatsschr. 21: 173 (1903)
Cameroon. Mundemba, Mana bridge, 4°58'N, 7°00'E, 11 Jan 1998, M. Cheek 8845 (holotype: K; isotype: YA).
Small erect shrub, up to 1.5 m; stem very flexible; leaves small and narrow, 2–5 × 0.3–0.5 cm; strongly rooted; white-flowered.
Ndian waterfalls at Bulu docks, 4°56'N, 8°51'E, 17 Jan 1985, D. W. Thomas 1985 (YA); Ndian River, west of Mundemba, 5°02'N, 8°53'E, 21 Jan 1986, J. Nemba & D. W. Thomas 319 (YA); Mundemba, Mana bridge, 4°58'N, 7°00'E, 11 Jan 1998, M. Cheek 8845 (YA).
Beds of swift-running rivers; seasonally inundated river banks; rocks at waterfalls, in evergreen rainforest.
Cameroon (Fig.
Eugenia dusenii is not listed on http://www.iucnredlist.org, but it was assessed as Vulnerable VU in
Biophytum kamerunense Engl. & R.Kunth ex Engl., Veg. Erde 9(3,1): 717 (1915)
Oxalis talbotii Baker f., Cat. Pl. Oban 16 (1913)
Liberia, 02 Nov 1910, Bunting, R. H. 103 (holotype: BM).
Perennial herb, woody stem, up to 30 cm high; roots spreading; leaves in shape of umbrella; flowers pink.
Njabilobé, 54 km southeast of Kribi, 12 Mar 1963, J. & A. Raynal 10425 (YA); Kienke River, Kribi, 2°56'N, 9°55'E, 20 Jun 1969, J. J. Boss 4900 (YA); near Numba, 45 km northeast of Mamfe, 5°50'N, 9°42'E, 18 Aug 1975, R. Letouzey 14331 (YA); Mamfe road, near Numba, 16 Dec 2012, F. Kuetegue 400 (YA) .
Riverbeds and earthbanks of shaded forest streams, periodically inundated rocks in rivers; in rainforest.
Cameroon (Fig.
Biophytum talbotii is not listed on http://www.iucnredlist.org nor assessed by
Cameroon, 01 Jan 1908, G. Zenker 3428 (BM, BR, G; HBG, K, K000419376, M, P, W).
Perennial herb, up to 30 cm tall, forming dense clumps; leaves in rosette or nearly so; flowers yellow.
Cross River ferry between Ikom and Manfe, 07 Apr 1955, J. K. Morton K318 (YA); Korup, rocky river bank of Mana River, 4°55'N, 8°50'E, 08 Jun 1983, D. W. Thomas 2164 (YA); Ndian Division Mundemba, in Mana River, 5°00'N, 8°50’E, 21 Nov 1986, Stephen D. Manning 896 (YA).
In rock crevices in riverbeds, seasonally flooded; in forest.
Angola, Cameroon (Fig.
Like the species before it, Biophytum zenkeri is not listed on http://www.iucnredlist.org. The taxon is currently known from 9 localities. The extent of occurrence of this species is about 80,000 km2 and its area of occupancy is about 36 km2. Plantation development is in progress at two of the localities and this may affect the survival of the species. Based on this threat, and the continuous decline of vegetation cover in the area, extent and /or quality of habitat B. zenkeri is here assessed as Vulnerable. IUCN Red List Category: Vulnerable VU B2ab (ii, iii).
Cameroon, near the Ndonga River (30 km W Edea), 20 Dec 1973, R. Letouzey 12472 (holotype: P; isotype: YA).
Shrub or small tree of about 5 m tall; strongly rooted; leaves narrow 60–80 × 2–4 cm, spine on the borders; fruit green.
Wouri River, near Bekoko, Douala-Nkongsamba road, 16 Jun 1983, Satabie 674 (YA); bed of Dilolo River at Bolomeboka, Nkonyé, 4°51'N, 9°28'E, 22 Mar 2011, F. Kuetegue 462 (YA); Mongo River at Mbakwa Super, Nkonyè, 5°01'N, 9°25'E, 24 Mar 2011, F. Kuetegue 463 (YA).
Banks of rivers subject to flooding.
Cameroon (Fig.
Pandanus satabiei was not assessed by
Eragrostis fluviatilis A.Chev., Bull. Mus. Nalt. Hist. Nat. sér 2, 20: 472 (1948)
Nigeria, 1858, C. Barter 877 (syntype: K, K000366508; isotype: P).
Perennial grass, robust, of about 1 m high; leaves lanceolate; inflorescence in open panicle.
Nkokmen II, at 8 km east of Yingui, at the bank of Makombe River, 4°32'N, 10°15'E, 09 Jan 1972, D. van der Zon 10939 (YA). Mpoumé falls on Nyong River, 9 km south of Makak 3°28'N, 11°00'E, 20 Jan 1977, J. Lowe 3188 (YA); Sanaga River at Nkongnjok, 4°10'N, 11°01'E, 12 Jan 1978, J. Lowe 3471 (YA); Kikot (Douala-Bafia road), near bridge, bank of Sanaga, 3°51'N, 11°30'E, 16 Dec 2012, F. Kuetegue 535 (YA).
Among rocks, and sandbanks on riverbed or streams.
Cameroon (Fig.
Eragrostis barteri was not assessed by
Ixora degemensis Hutch. & Dalziel, Fl. W. Trop. Afr. 2: 86 (1931)
Cameroon. Bipindi, bank of Lokoundje River, 02 Oct 1896, G. Zenker 1108, (holotype: K; isotypes: BR, HBG, MO, WAG, Z).
Shrub or small tree up to 5 m tall; leaves narrowly elliptic-oblong 10–19 × 2–4.5 cm; inflorescence terminal.
Lobe River, 7 km south of Kribi, 2°53'N, 9°54'E, 20 Feb 1969, J. J. Bos 3940 (YA); Songloulou falls, at 25 km southwest of Ngambé, Massock-Songloulou road, 3°35'N, 9°44'E, 24 Jan 1972, R. Letouzey 11103 (YA); 5 km southeast of Bipindi, 3°04'N, 10°25'E, 14 Jan 1987, Stephen D. Manning 1343 (YA); Nguti-Ntalè, Mbièr River, 5°15'N, 9°34'E, 13 Dec 2010, F. Kuetegue 226 (YA).
Inundated sandy or rocky banks of rivers, between rocks in streams or rivers, waterfalls; riverine forest.
Cameroon (Fig.
Ixora euosmia was not assessed by
Gabon. Cristal Mountains, 1862, Mann 1731 (holotype: K; isotype: P).
Shrub up to 1.5 m tall; strongly rooted; stems tough; leaves lanceolate 4–11 × 1–2.5 cm; flowers translucent white.
Near Nkolemvom, 20 km southeast of d’Ebolowa, 2°54'N, 11°09'E, 03 Mar 1970, R. Letouzey 9986 (YA); between Bulu and Ekum Bako, SW Region, 4°56'N, 8°52'E, 01 Jun 1984, D. W. Thomas 3499 (YA); at the bank of Cross River, north of Nsanaragati, 5°52'N, 8°54'E, 16 Dec 1986, Stephen D. Manning 1217 (YA).
Rocky bank of rivers, periodically inundated; between rocks in rivers.
Cameroon (Fig.
Ixora inundata is not listed on http://www.iucnredlist.org. However, in
Virecta angustifolia Hiern, Fl. Trop. Afr. 3: 48 (1877)
Virecta heteromera K.Schum., Bot. Jahrb. Syst. 23(3): 422 (1896)
Virectaria heteromera (K.Schum.) Bremek., Verh. Kon. Ned. Akad. Wetensch., Afd. Natauurk., Sect. 2, 48(2): 21 (1952).
Gabon, Mounts of Cristal, July 1862, G. Mann 1686 (holotype: K).
Erect herb, up to 30 cm tall; leaves linear to oblanceolate 5–15 × 1–2 mm; flowers white.
50 km southeast of Kribi, 2°42'N, 10°12'E, 14 Mar 1968, R. Letouzey 9011 (YA); bank of Mana River at Ndian, 4°58'N, 8°51'E, 09 Dec 1983, D. W. Thomas 50588 (YA); Ndian River northwest of Mundemba, 00 Oct 1986, Stephen D. Manning 894 (YA); Ntale, bank and bed of Mbier and Essembe River, 23 Dec 2010, F. Kuetegue 319 (YA).
Rocks of riverbeds and inundated banks, up to flood level of streams and rivers, submerged during rainy season.
Cameroon (Fig.
Virectaria angustifolia is not listed on http://www.iucnredlist.org, nor assessed by
Virecta salicoïdes C.H.Wright, Bull. Misc. Inform. Kew 1898(1430): 302 (1898)
Cameroon, Mfoa, rocky bank of Mbei River, 00 Oct 1827, G. L. Bates 527 (holotype: K; isotypes: BM, P).
Herb 25 cm high; stems flexible and tough; strongly rooted; leaves narrow 3–9 × 0.5–0.9 cm; inflorescence terminal.
Nkolebenga, northwest of d’Ebianemeyong, near Nyabesan, 60 km east of Campo, 2°25'N, 10°20'E, 11 Apr 1970. R. Letouzey 10357 (YA).
Rocks at banks and beds of rivers and streams.
Cameroon (Fig.
Virectaria salicoides is not listed on http://www.iucnredlist.org, nor assessed by
Cameroon – SouthWest Region, near Mundemba, 4°56'N, 8°52'E, rocky bank of Idu River at Bulu on path to Ekumbako, 10 m, 07 Mar 1984, D. W. Thomas 3253 (holotype: MO; isotypes: K, P, YA).
Stenophyllous shrub of about 1 m high; roots spreading and deep; stems strong but flexible; leaves narrow 20–25 × 1–1.5 cm, grouped at the summit of the stem.
Korup Reserve, 4°55'N, 8°50'E, 16 Jul 1983, D. W. Thomas 2243 (YA); between Bulu and Dibunda, 4°55'N, 8°52'E, 07 Mar 1984, D. W. Thomas 3253 (YA); between Bulu and Ekumbako, 4°56'N, 8°52'E, 00 Jun 1984, D. W. Thomas 3497 (YA).
Rocky bed of rivers, on banks of streams and rivers.
Cameroon (Fig.
Deinbollia angustifolia is listed on http://www.iucnredlist.org as Vulnerable by
Cameroon, Ndian, Kumba, 03 Mar 1936, Smith Cam 80/36 (holotype: K, K000093228; isotype: FHI).
Shrub or small tree up to 2.5 m tall; sparingly to much branched; branches thick; stems strong and flexible; leaves clustered terminally; lanceolate 6–10 × 0.5–1 cm; flowers white.
Canyon of Ntem, 20 km southwest of Nyabessan, 01 Dec 1982, B. A. Nkongmeneck 410 (YA); Mana River at Korup, 4°55'N, 8°50'E, 00 Dec 1983, D. W. Thomas 2205 (YA); Ndian, on Ndian (Mana) waterfall, 4°56'N, 8°51'E, 17 Jan 1985, D. W. Thomas 4268 (YA).
Inundated rocky bed and bank of rivers or streams.
Cameroon (Fig.
Deinbollia saligna is listed on www.iucnredlist.org. It was assessed globally as Vulnerable (World Conservation Monitoring Centre, 1998). In
The present study and herbarium data have shown that 43 species in 12 genera in the Podostemaceae (riverweed) family have so far been documented from the study area. The results revealed six monotypic genera: Leiothylax, Letestuella, Stonesia, Tristicha, Winklerella, and Zehnderia. The genus Inversodicraea has 10 species, Saxicolella has four while three genera Dicraeanthus, Djinga, and Macropodiella have two; and the largest genus in our area Ledermanniella has 17 species. In an earlier work
Description. Podostemaceae are annuals or perennials, that grow attached to rocks, in fast-flowing water, by rhizoids, or expanded holdfast; resembling algae or mosses. They produce flowers and fruits during the dry season when the water level in the rivers or streams drops.
Dicraeanthus ramosus H.E.Hess, Ber. Geobot. Inst. Eidg. Techn. Hochsch. Rübel Heft 32: 187 (1961).
Cameroon, Winkler 901 (holotype: B).
Edea at Sanaga waterfall, Annet 498 (P); 8 km S Kribi Lobe fall, J.J. Bos 3590, 3887, 3888 (K, WAG); Ngaoundere, Vina waterfall, Dulieu 4 (P); Natchigal, 62 km southeast of Bafia, J. & A. Raynal 10544 (P).
River rapids and waterfalls.
Cameroon (Fig.
Dicraeanthus africanus has been assessed for the IUCN Red List, globally, in 2007 as Least Concern (
Cameroon, Edea, 30 Jan 1951, Zehnder 259 (syntype: Z, ZT).
Edea at Sanaga waterfall, Zehnder 259, 260, 262 (ZT); Sanaga waterfalls, 30 Jan 1951, Hess 51/270 (ZT).
Growing in river rapids and waterfalls of Sanaga.
Cameroon (Fig.
Dicraeanthus zehnderi was listed on http://www.iucnredlist.org as Critically Endangered (
Cameroon, near Manjo, 12 Jan 2011, J. P. Ghogue 2125 (YA, Z, ZT).
Littoral Province, Mantem River, near Manjo, on the Douala – Nkongsamba highway, 4°49'N, 9°46'E, 12 Jan 2011, J.-P. Ghogue 2126 and 2128 (K, YA, Z, ZT); Mbo River, Manjo (Manengole Village), 4°52'N, 9°51'E, 12 Dec 2004, R. Imaichi, Y. Kita and J.-P. Ghogue CMR35 (TNS, Z, ZT).
River rapids.
Cameroon (Fig.
Djinga cheekii is not listed on the http://www.iucnredlist.org. The taxon is known only from the type locality, Mantem River near Manjo. The extent of occurrence is estimated as 4 km2, and area of occupancy is about 4 km2. The main threat at the locality is agriculture. Based on this threat, and the continuous decline of vegetation cover in the area, extent and /or quality of habitat the taxon is here assessed as Critically Endangered. IUCN Red List Category: Critically Endangered CRB1+2ab (iii).
Cameroon, Adamawa, north of mount Djinga, 29 Oct 1967, H. Jacques – Felix. 8889 (holotype: P).
Adamawa stream, north of mount Djinga, 29 Oct 1967, Jacque-Félix 8889 (holo-P).
Mt. Djinga, Adamaoua, near Tignere, river rapids.
Cameroon (Fig.
This taxon, D. felicis, has not yet been assessed for the IUCN Red List. This species was assessed by
Cameroon, West of Nyabezan, 01 Dec 1992, D.W. Thomas & G. Achoundong 9642 (YA).
Ntem River, west of Nyabessan, 02°24'N, 10°22'E, 01 Dec 1992, D. W. Thomas & G. Achoundong 9642 (YA).
Memve’ele waterfalls, Ntem River, alt. 395 m.
Cameroon (Fig.
Inversodicraea achoundongii is yet to be assessed for the IUCN Red List. The taxon is currently known only from the type locality at Memve’ele waterfalls on the Ntem River. The extent of occurrence and area of occupancy are both estimated at 4 km2 each. The proposed hydropower dam on the Ntem River will certainly impact the survival of the species. Based on this threat, the species is here assessed as Critically Endangered. IUCN Red List Category: Critically Endangered CRB1+2ab (iii).
Ledermanniella bosii C.Cusset, Bull. Mus. Natl. Hist. Nat., B, Adansonia 4: 385 (1984)
Cameroon, South of Kribi, 08 Jan 1969, J.J. Bos 3592 (YA). Basionym: Ledermanniella bosii C.Cusset, Bull. Mus. Natl. Hist. Nat., B, Adansonia 4: 385 (1984).
South of Kribi on Lobe waterfall, 08 Jan 1969, J.J. Boss 3592 (K, WAG, P); near Bongola, Ntem waterfall, Dec, R. Letouzey 15333 (P); South Region, south Kribi, Lobe waterfall, 08 Jan 1969, J.J. Boss 3597 (WAG).
Lobe waterfall, south of Kribi.
Cameroon (Fig.
Inversodicraea bosii is listed on http://www.iucnredlist.org. The taxon was assessed as Endangered (
Ledermanniella cristata (Engl.) C.Cusset, Adansonia sér. 2, 14(2): 273 (1974)
Cameroon, near Malaka, Nov, Ledermann 1173 (lectotype: B).
Near Malaka, 500 m alt., Nov, Ledermann 1173, 1189 (U); Mari River waterfall, c. 8 km north of Betare Oya, 05 Feb 1966, Leeuwenberg 7761 (WAG, YA); in Mvigili, northwest of Moan, 24 km southeast of Nyabezan, Mar, J. & A. Raynal 10263 (P); Maan (24 km southeast of Nyabezan), rocky bank of Mvigili River, northwest of the village, 06 Mar 1963, J. & A. Raynal 10263 (P, YA).
River rapids.
Angola, Cameroon (Fig.
Inversodicraea cristata is listed on http://www.iucnredlist.org. The taxon was assessed globally as Vulnerable (
Cameroon, Yabassi, near Locndeng, 07 Dec 2013, van der Burgt 1716 (YA).
Cameroon, Littoral Region, Yabassi, near Locndeng, Ebo River, 07 Dec 2013, van der Burgt 1716 (YA).
On rocks in river rapids.
Cameroon (Fig.
Inversodicraea ebo is not listed on http://www.iucnredlist.org. The taxon is known only from the type locality. The extent of occurrence and the area of occupancy are both estimated at about 4 km2 each. The main threats at the locality are forest logging, mining and agriculture. The species is here assessed as Critically Endangered. IUCN Red List Category: Critically Endangered CRB1+2ab (iii).
Cameroon, Campo Ma`an area, 30 Nov 2001, M. Elad & P. Tchouto 1485A (YA).
Cameroon, South Region, Campo Ma’an area, Lobe, Lobe waterfalls, 30 Nov 2001, M. Elad & P. Tchouto 1485A (YA).
On rocks in waterfall near the sea, in evergreen forest zone.
Cameroon (Fig.
Inversodicraea eladii as for the species before it is not as yet assessed for the IUCN Red List. The taxon is known from one locality. The extent of occurrence and the area of occupancy are both estimated at 4 km2 each. The main threat at the locality is touristic activity. The species is here assessed as Critically Endangered. IUCN Red List Category: Critically Endangered CRB1+2ab (iii).
Ledermanniella kamerunensis (Engl.) C.Cusset, Adansonia sér. 2, 14(2): 274 (1974).
Cameroon, Campo, near Dipikar, Aug, Ledermann 440a (YA).
Campo River waterfalls, near Dipikar, 00 Aug 1908, Ledermann 440a (YA).
Waterfalls in low altitudes.
Cameroon (Fig.
Inversodicraea kamerunensis is listed on http://www.iucnredlist.org as Vulnerable (
Ledermanniella ledermannii (Engl.) C.Cusset, Adansonia sér. 2, 14(2): 274 1974)
Cameroon, South Region, near Kribi, Grand Batanga, Ledermann 225 (YA).
SW Region, Korup National Park, 5°01'N, 8°50'E, 50 m, 5–15 Dec 1984, D.W. Thomas 4135A (K, P); near Kribi, Lobe waterfalls, Grand Batanga, Ledermann 225 (U); 6 km from Kribi, Lobe waterfalls, De Wilde 2875 (P, YA).
River rapids.
Angola, Cameroon (Fig.
Inversodicraea ledermannii is listed on http://www.iucnredlist.org as Least Concern, globally (
Ledermanniella ntemensis Y.Kita, Koi, Rutish. & M.Kato; Acta Phytotax. Geobot. 59: 224 (2008)
Cameroon, R. Imaichi Kita, Y. & J. P. Ghogue CMR 65 (YA). Basionym: Ledermanniella ntemensis Y.Kita, Koi, Rutish. & M.Kato; Acta Phytotax. Geobot. 59: 224 (2008).
South Region, Canon of Ntem, 30 km southwest of Nyabessan, 01 Dec 1982, Nkongmeneck 420 (YA); Ntem waterfalls, near Bongola, 40 km southeast of Campo, 10 Dec 1979, R. Letouzey 15333 (P, YA); Campo a’an area, Memve’ele waterfalls, 2°24'N, 10°21'E, 17 Jan 2002, P. Tchouto 3373 (K, KRI, SCA, WAG, YA).
Rapids of Ntem River.
Cameroon (Fig.
Inversodicraea ntemensis is not listed on http://www.iucnredlist.org. It was assessed in
Cameroon, P. Tchouto 3378 (YA).
South Region, Campo Ma’an Area, Boucle du Ntem, near Meyas Ntem, 2°20'N, 10°35'E, 480 m alt., 16 Feb 2001, P. Tchouto 3170 (K, KRI, SCA, WAG); Memve’ele waterfalls, 2°24'N, 10°21'E, 360 m alt., 17 Jan 2002, P. Tchouto 3376 (K, KRI, SCA, R. Letouzey 10299 (P).
Waterfalls in evergreen forest.
Cameroon (Fig.
Inversodicraea tchoutoi has not yet been assessed for the IUCN Red List. The taxon is known from only the Memve’ele waterfalls. The extent of occurrence is about 2 km2, and the area of occupancy is also about 2 km2. The main threat is the construction of a dam on the Ntem River and touristic activities. The species is here assessed as Critically Endangered. IUCN Red List Category: Critically Endangered CRB1+2ab (ii, iii).
Cameroon, Campo, 04 May 2016, van der Burgt 1940 (holotype: K; isotypes: P, Z).
South Region, Campo, Campo-Ma’an National Park, north of the road Campo to Ma’an, 2°20'N, 10°13'E, 230 m alt., 04 Mar 2016, van der Burgt 1940 (holotype: K; isotype: P, YA, Z).
On rocks in streams.
Cameroon (Fig.
Inversodicraea xanderi is not listed on http://www.iucnredlist.org. The taxon is currently known only from Campo. The extent of occurrence is estimated at 4 km2, and the area of occupancy is also about 4 km2. No major threat is known from the locality where the species occurs, therefore, I. xanderi is currently assessed as Near Threatened. IUCN Red List Category: Near Threatened (NT).
Inversodicraea aloides Engl., Veg. Erde 9(3, 1): 271 (1915)
Cameroon, Tschape pass, near Tchabal Mbabo, Ledermann 2785 (lectotype: B; isotype: U).
Nigeria, Butum River, Keay FHI 25150; Utanga, Butum River, Keay FHI 25153; Tschape pass, near Tchabal Mbabo, Ledermann 2785 (U).
On rocks in river.
Cameroon (Fig.
Ledermanniella aloides has been assessed globally as Vulnerable by
Dicraeia batangensis Engl., Bot. Jahrb. Syst. 43(4): 380 (1909)
Inversodicraeia batangensis Engl., Veg. Erde 9(3, 1): 271 (1915)
Cameroon, Grand Batanga, Ledermann 221 (holotype: B). Basionym: Dicraeia batangensis Engl., Bot. Jahrb. Syst. 43(4): 380 (1909).
Grand Batanga, Lobe waterfalls, Ledermann 221 (holotype: B, isotype: U).
On rocks in waterfalls.
Cameroon (Fig.
Ledermanniella batangensis is listed on http://www.iucnredlist.org globally as Critically Endangered (
Inversodicraea bifurcata Engl., Veg. Erde 9(3, 1): 273 (1915)
Cameroon, Kribi, Mildbraed 5951 (holotype: B).
Bipindi, Annet 321 (P); 10 km from Kribi-Lolodorf, Kienke rapids, J.J. Bos 7071, 7072 (WAG); 33 km northeast of Eta, 60 km southeast of Ngoila, Nki waterfalls, R. Letouzey 11949 (P); 50 km east of Grand Batanga, Kribi waterfalls, Mildbraed 5951, 5952, 5952a (YA).
River rapids and waterfalls in evergreen forests.
Cameroon (Fig.
Ledermanniella bifurcata has been assessed globally as Vulnerable (
Inversodicraea keayi G.Taylor; Bull. Brit. Mus. (Nat. Hist.) Bot. 1: 78 (1953)
Cameroon, Kumbo, Keay FHI 28457 (holotype: K).
Cameroon: Banso, Bamenda, Keay FHI 28457 (YA); near Sagbo, Ndop near Bamenda, 1800 m alt., C. D. Adams 11073 (LISC); Kumbo, 1650 m alt., Keay FHI 28457 (K).
River rapids.
Cameroon (Fig.
Ledermanniella keayi is listed on http://www.iucnredlist.org as Critically Endangered (
Cameroon, near Lokando, Mount Rumpi, Ure, 23 Mar 1976, R. Letouzey 14517 (YA).
30 km northwest of Kumba, near Lokando, Mount Rumpi, Ure, on river, Mar, R. Letouzey 14517 (holotype P, isotype YA).
River rapids and waterfalls in tropical forests.
Cameroon (Fig.
Ledermanniella letouzeyi is listed on http://www.iucnredlist.org. The taxon was assessed as Endangered by
Sphaerothylax linearifolius Engl., Veg. Erde 9(3, 1): 275 (1915)
Cameroon, 28 Aug 1908, C. Ledermann 440 (YA).
7 km south of Kribi, Lobe waterfall, Jan, J. Bos3591 (K); 7 km south of Kribi, Lobe waterfalls, Aug, De Wild 2876 (P, WAG, YA); Nkam, near Sahe, 3 km southwest Nkondjok road Bafang-Yabassi, Feb R. Letouzey 11146 (P).
River rapids and waterfall.
Cameroon (Fig.
Ledermanniella linearifolia is listed on http://www.iucnredlist.org. It was assessed as Endangered (
Monandriella linearifolia Engl., Bot. Jahrb. Syst. 60(4): 457 (1926)
Cameroon, Mao Bika, near Dodeo, 05 Mar 1909, C. Ledermann 2872 (YA).
Mao Bika, near Dodeo, 60 km west of Tignere, 700 m alt., Mar, Ledermann 2872 (holotype B).
River rapids.
Cameroon (Fig.
Ledermanniella monandra has not yet been assessed for the IUCN Red List, but it was assessed in
Inversodicraea musciformis G.Taylor; Bull. Brit. Mus. (Nat. Hist.) Bot. 1: 75 (1953)
Cameroon, Mba Kokeka, near Bamenda, Jan, Keay FHI 28542 (holotype: K). Basionym: Inversodicraea musciformis G.Taylor; Bull. Brit. Mus. (Nat. Hist.) Bot. 1: 75 (1953).
Northwest slopes of Mts. Mba Kokeka, near Bamenda, Jan, Keay FHI 28542 (K); Tchamba, Nakalba, 21 km southwest of Tchamba 1200 m alt., Jan, J. & A. Raynal 13166 (P).
River rapids and waterfalls.
Cameroon (Fig.
Ledermanniella musciformis is listed on http://www.iucnredlist.org as Data Deficient (
Cameroon, Bakossi Mts, northwest of Muambong, 04 Feb 1998, J.-M. Onana 558 (K, YA).
Cameroon: South West Province, Bakossi Mts., Chide River falls, northwest of Muambong, 04 Feb 1998, J.-M. Onana 558 (YA, K); South West Province, Bakossi Mts., Ndip River rapids between Nzimbeng and Kodmin, alt. 1150 m. fl. & fr., 14 Feb 1998, M. Cheek 9196 (K, YA).
Perennial waterfalls and river rapids in submontane forest.
Cameroon (Fig.
Ledermanniella onanae is listed on http://www.iucnredlist.org as globally Endangered (
Cameroon, North Western Province, Bali, 1 km east, 5°52'N, 10°01'E, 19 Nov 2000, B. Pollard 536 (K, YA).
Cameroon, North-western Province, Bali, 1 km east, 5°52'N, 10°01'E, 1280 m alt. fl., 19 Nov 2000, B. Pollard 536 (K, YA).
Perennial waterfall, in full sun, in deforested area.
Cameroon (Fig.
Ledermanniella pollardiana is not as yet assessed for the IUCN Red List.
Cameroon, 01 Dec 1990, D.W. Thomas 11550 (K, WAG, YA).
Cameroon, 01 Dec 1990, D.W. Thomas 11550, [K, WAG, YA].
River rapids.
Cameroon (Fig.
Ledermanniella prasina was assessed as Vulnerable (
Dicraeanthus pusillus C.H.Wright, Fl. Trop. Afr. 6(1.1): 127 (1909)
Sphaerothylax pusilla Warm Kongel. Danske Vidensk. Selsk. Skr., Naturvidensk. Math. Afd. VI, 9: 146 (1899)
Cameroun, Bipindi, G. Zenker 1050 (holotype: B; isotype: G). Basionym: Sphaerothylax pusilla Warm., Kongel. Danske Vidensk. Selsk. Skr., Naturvidensk. Math. Afd. VI, 9: 146 (1899).
7 km south of Kribi, Lobe waterfall, J.J. Bos 3598 (WAG); Lokoundje waterfall, Bipindi, G. Zenker 1050 (G, K, L, M, U, Z).
Waterfalls.
Cameroon (Fig.
Ledermanniella pusilla is listed on http://www.iucnredlist.org globally as Endangered (
Cameroon, Natchigal, J. & A. Raynal 10543 (YA).
Cameroon, J. & A. Raynal 10543 (YA); Natchigal, Sanaga waterfall, A. & J. Raynal 10542 (P).
River rapids and waterfalls.
Cameroon (Fig.
Ledermanniella sanagaensis is listed on http://www.iucnredlist.org as Critically Endangered (
Dicraeia schlechteri Engl., Bot. Jahrb. Syst. 43: 381 (1909)
Inversodicraeia tenuissima Hauman, Bull. Jard. Bot. État 17: 180 (1944)
Congo Democratic Republic, 01 Jun 1899, R. Schlechter12574 (K). Basionym: Dicraeia schlechteri Engl., Bot. Jahrb. Syst. 43: 381 (1909).
Dehane, between Edea and Kribi, Jun, Annet 459 (P).
River rapids and waterfalls.
Cameroon (Fig.
Ledermanniella schlechteri is listed on http://www.iucnredlist.org as Vulnerable, globally (
Inversodicraeia thalloidea Engl., Veg. Erde 9(3, 1): 274 (1915)
Cameroon, Ndoungue near Nkongsamba, Ledermann 6328a (lectotype: B; isotypes: BM, U). Basionym: Inversodicraeia thalloidea Engl., Veg. Erde 9(3, 1): 274 (1915).
Tributary of Sanaga, 10 km north of Edea, Kers 1904 (LISC); Ndoungue near Nkongsamba, 800 m alt., Ledermann 6328a (BM, U); Natchigal, Sanaga waterfall, A. & J. Raynal 10542 (P).
Habitat. River rapids and waterfalls in tropical rain forest.
Cameroon (Fig.
Ledermanniella thalloidea is listed on http://www.iucnredlist.org as Endangered (
Cameroon, 14 Jan 1965, J. & A. Rayanal 12988 (YA).
Cameroon, 14 Jan 1965, J. & A. Rayanal 12988 (YA).
River rapids.
Cameroon (Fig.
Ledermanniella raynaliorum is not listed on http://www.iucnredlist.org.
Inversodicraeia variabilis G.Taylor, Bull. Brit. Mus. (Nat. Hist.) Bot. 1: 75 (1953)
Cameroon, Manfe, Munaya, Keay FHI 28688, (holotype: K). Basionym: Inversodicraeia variabilis G.Taylor, Bull. Brit. Mus. (Nat. Hist.) Bot. 1: 75 (1953).
Lobe waterfall, 7 km south of Kribi, J.J. Boss 3594 (WAG); Mamfe, Munaya River, Keay FHI 28688 (K).
River rapids and waterfalls.
Cameroon (Fig.
Ledermanniella variabilis is listed on http://www.iucnredlist.org as Endangered (
Dicraeia quangensis Engl., Bot. Jahrb. Syst. 20(1–2): 134 (1894)
Leiocarpodicraea buesgenii Engl., Engl. Bot. Jahrb. Syst. 60: 465 (1926)
Leiothylax buesgenii Warm. ex Engl., Nat. Pflanzenfam. 18 a ed. 2, 58 (1930)
Leiothylax edeensis Engl. Nat. Pflanzenfam. 18 a ed. 2, 58 (1930)
Democratic Republic of Congo, Teuscz in von Mechow’s Expedition 506 (holotype: M; isotype: G).
Edea, Sanaga waterfall, Buesgen 439 (M); Sanaga waterfall, Buesgen s.n. (B, U).
River rapids and waterfalls in tropical rain forests.
Angola, Cameroon (Fig.
Leiothylax quangensis has been assessed for the IUCN Red List as Endangered (
Letestuella chevalieri G.Taylor, Bull. Brit. Mus. (Nat. Hist.), Bot. 1: 59 (1953)
Leiothylax warmingii (Engl.) Warm., Danske Vid. Selsk. Skrift. Ser. VI. ix 150 (1899)
Central African Republic, Tisserant 1769 (holotype: BM; isotype: P).
Near Goyoum in Sanaga River, 20 km west of Deng Deng, F.J. Breteler 981 (WAG); Plateau de l’Adamaoua, Vina waterfall, 15 km from Ngaoundere, Zehnder 163 (ZT).
River rapids and waterfalls in tropical rain forest.
Benin, Cameroon (Fig.
Letestuella tisserantii is listed on http://www.iucnredlist.org as Least Concern (
Sphaerothylax heteromorpha Baill., Bull. Mens. Soc. Linn. Paris ii 876 (1890)
Macropodiella mildbraedii Engl., Bot. Jahrb. Syst. 60(5): 466 (1926)
Gabon, Thollon 729 (holotype: P). Basionym: Sphaerothylax heteromorpha Baill., Bull. Mens. Soc. Linn. Paris ii 876 (1890).
Makak Forest Reserve, P. Bamps 1453 (YA); Nyong River, near Mbalmayo, Mildbraed 7749, 7750 (B, U).
River rapids and waterfalls in tropical rainforests.
Cameroon (Fig.
Macropodiella heteromorpha is listed on http://www.iucnredlist.org as Vulnerable (
Cameroon, Bare, near Nkongsamba, Ledermann 6142 (lectotype: BM). Basionym: Inversodicraea pellucida Engl., Veg. Erde 9(3, 1): 271, 272. (1915).
Bare, near Nkongsamba, on rocks in a waterfall, Ledermann 6142 (BM); Ndian River, near Mundemba, Dec, D.W. Thomas 2552 (MO, P).
River rapids and waterfalls in rainforest.
Cameroon (Fig.
Macropodiella pellucida is listed on http://www.iucnredlist.org as Endangered (
Pohliella flabellata G.Taylor, Bull. Brit. Mus. (Nat. Hist.), Bot. 1: 53 (1953)
Nigeria, Afi River, Dec, Keay FHI 28240 (K). Basionym: Pohliella flabellata G.Taylor, Bull. Brit. Mus. (Nat. Hist.), Bot. 1: 53 (1953).
Nigeria: Afi River, on Aboabam-Boje path, Dec, Keay FHI 28240 (K); Cameroon: Ndian, near Mundemba, D.W. Thomas 2654 (MO, P).
Submerged on rocks in fast-flowing river.
Cameroon (Fig.
Saxicolella flabellata is list on http://www.iucnredlist.org. The taxon has been assessed as Data Deficient (
Inversodicraea laciniata Engl., Veg. Erde 9(3, 1): 271 (1915)
Pohliella laciniata Engl., Bot. Jahrb. Syst. 60(4): 458 (1926)
Cameroon, near Babong, Ledermann 1185 (holotype: B). Basionym: Pohliella laciniata Engl., Bot. Jahrb. Syst. 60(4): 458 (1926).
Dinger River near Babong, Ledermann 1185 (B); Bawan River, on path to Agborkem (ex Ossidinge) at Tabo, 20 km west of Mamfe, R. Letouzey 13731 (YA).
River rapids.
Cameroon (Fig.
Saxicolella laciniata is listed on http://www.iucnredlist.org as Vulnerable (
Butumia marginalis G.Taylor, Bull. Brit. Mus. (Nat. Hist.) Bot. 1: 55 (1953).
Nigeria, 25 Dec 1948, Keay, Savory & Russell, #25152 (BM). Basionym: Butumia marginalis G.Taylor, Bull. Brit. Mus. (Nat. Hist.) Bot. 1: 55 (1953).
Nigeria: Butum River, Utanga, 2 miles north of Bagga, Obudu, 25 Dec 1948, Keay, Savory & Russell FHI 25152 (YA); Cameroon: Fundong, 22 Nov 1996, M. Cheek 8740 (YA).
On smooth granite rocks in swift-flowing stream or river.
Cameroon (Fig.
Saxicolella marginalis is listed on http://www.iucnredlist.org. The taxon has been assessed globally as Critically Endangered (
Cameroon, near Mbalmayo, Mildbraed 7749a (holotype: B; isotype: U).
Cameroon, near Mbalmayo, Nyong River, 644 m alt, Mildbraed 7749a (YA); 11°27'N, 3°22'E, 28 Feb 2007, M. Kato, R. Imaichi, S. Koi, & N. Katayama CMR-129 (YA).
River rapids and waterfalls.
Cameroon (Fig.
Saxicolella nana is listed on http://www.iucnredlist.org as Vulnerable (
Cameroon, Adamawa, Ngaoundere, 16 Feb 2005, J. P. Ghogue 1665 (YA, K, Z).
Adamawa, Ngaoumdere, Tello Waterfalls, 16 Feb 2005, J. P. Ghogue 1665 (YA, K, Z).
Growing in waterfalls, Tello Waterfalls, Ngaoundéré, Adamawa (Cameroon).
Cameroon (Fig.
Stonesia ghoguei is listed on http://www.iucnredlist.org as Vulnerable (
Dufourea boryi A.Rich., Dict. Class. Hist. Nat. 5: 636 (1824)
Dufourea hypnoides St-Hil. Mém. Mus. Hist. Nat. 10: 472 (1823)
Dufourea trifaria Bory ex Willd., Sp. Pl., ed. 4 5(1): 55 (1810)
Dufourea alternifolia Willd., Mag. Neuesten Entdeck. Gesammten Naturk. Ges. Naturf. Freunde Berlin 6: 64 (1812)
Tristicha alternifolia Thouars ex Spreng., Syst. Veg. ed. 16(1): 22 (1824)
Tristicha alternifolia Thouars, ex Roem. & Schult. Syst. Veg. i. 50 (1817)
Mauritius, Bory de St Vincent s.n. (holotype: B; isotype: P).
8 km south of Kribi, Lobe waterfall, J.J. Bos 3593 (YA); Vina waterfall, near Ngaoundere, Feb, Dulieu 5 (ALF); Hossere Koum, 40 km west of Tchollire, Nov, Fotius 2418 (P); Limbe (Joke River), Mar, Brenen 9495, 9496 (BR, COL, P, SRGH); 8 km North Betare Oya (Mari River fall), Nov, Leeuwenberg 7767 (P, WAG); Roua 20 km northeast of Mokolo, Oct, R. Letouzey 7280 (P); Sahe, 3 km southwest of Nkondjok (Bafang – Yabassi Road), Nkam River, Feb, R. Letouzey 11145 (P).
River rapids and waterfalls.
AFRICA; Angola, Benin, Burkina Faso, Cameroon (Fig.
Tristicha trifaria is not listed on www.iucnredlist.org. The extent of occurrence of T. trifaria is about 12,000 km2 and the area of occupancy is about 28 km2. The taxon is currently known from about 7 localities. Lobe area, one of the localities where the species is found is a famous touristic site. Also agricultural activities are on the increase in other localities. Based on these threats, the number of localities and the continuous decline of vegetation cover in the area, extent and /or quality of the habitat, T. trifaria is here assessed as Vulnerable. IUCN Red List Category: Vulnerable VUB1 + 2ab (ii, iii).
Cameroon, Edea, 30 Jan 1951, Winkler 900 (holotype: B).
Edea waterfall, Winkler 900 (B); Edea waterfall, 30 Jan 1951, Zehnder 271, 275, 277 (BR, ZT).
River rapids and waterfalls.
Cameroon (Fig.
Winklerella dichotoma is list on http://www.iucnredlist.org as Critically Endangered (
Cameroon, Edea, 29 Jan 1951, Zehnder 264 (holotype: ZT).
Edea, Sanaga waterfall, 29 Jan 1951, Zehnder 264, 276, 278 (ZT).
Cameroon (Fig.
Zehnderia microgyna is listed on http://www.iucnredlist.org. as Critically Endangered (
The survey of rheophytic plants from Cameroon revealed 66 species distributed in 16 families, and in three major plant groups: 2 ferns, 8 monocotyledons, and 56 dicotyledons (Table
Family | Genus | Species |
---|---|---|
Ferns | ||
Lomariopsidaceae | 1 | 2 |
Dicotyledons | ||
Acanthaceae | 1 | 1 |
Amaranthaceae | 1 | 1 |
Apocynaceae | 1 | 1 |
Lamiaceae | 1 | 1 |
Myrtaceae | 1 | 1 |
Oxalidaceae | 1 | 2 |
Podostemaceae | 12 | 43 |
Rubiaceae | 2 | 4 |
Sapindaceae | 1 | 2 |
Monocotyledons | ||
Amaryllidaceae | 1 | 1 |
Araceae | 1 | 1 |
Cyperaceae | 2 | 3 |
Melastomataceae | 1 | 1 |
Pandanaceae | 1 | 1 |
Poaceae | 1 | 1 |
Invariably, the species encountered in the study have characteristic features that adapt them to their peculiar habitats, and enable them to persist in the harsh conditions of swift-flowing water, flush floods, torrents, and waterfalls. The leaves are lanceolate or narrow with a leaf index of at least 3 similar to what
The habitats of this unique biological group are, however, threatened by human activities. We show that about 36% of rheophytes are Critically Endangered (CR) in Cameroon and only 2% are considered to be of Least Concern (Fig.
The habitats of rheophytes in Cameroon and indeed across Africa are threatened by the land use practices around the rivers, and the damming of the rivers for hydroelectric power (
The recent upsurge in dam construction effort in many African countries raises concern for the survival of rheophytes. In Cameroon, there are a number of dams built across rivers for hydropower, and efforts are continuing to build many more dams across a number of rivers: (http://www.theworldfolio.com/news/hydroelectric-projects/659/eroon); examples of these are:, Memve’élé hydroelectric dam on Ntem River(http://www.edennewspaper.net/memveele-hydroelectric-dam-is-60-complete-energy-minister/); Mekin hydro-electric dam on Dja River, Lom-Pangar hydroelectric dam on Lom River (https://www.internationalrivers.org/sites /default/files/attached-files/lp_factsheet.pdf); Menchum hydroelectric dam on Menchum River, and the Natchigal hydroelectric dam on Sanaga Rive1r at Edea; http://www.hydroworld. com/ articles/2013/11/cameroon-makes-deal-for-330-mw-nachtigal-falls-hydropower-project. html; and https://afrique.edf.com/en/edf-in-africa/news/a-new-phase-for-the-nachtigal-hydroelectric -project).
River rapids, cataracts, and waterfalls, are usually the preferred sites for dam construction for hydro-electric power, and also the habitats for many rheophytes, particularly the Podostemaceae. The rheophytes have become permanently submerged upstream of the dam due to flood water. The plants downstream are subjected to a different threat, that is, the change in flow rate and absence of flash floods below the dam (
We would like to thank the many individuals who have helped in diverse ways to enable the completion of this study. The contribution of those who helped in the field work is hereby acknowledged. Special thanks also go to the Director of the National Herbarium of Cameroon (YA) for the use of herbarium facilities. We thank the staff of the Plant Systematic and Ecology Laboratory of the Higher Teacher Training College for their assistance while doing this work. The support of Dr. Atanga Ekobo, former coordinator of WWF-CFP Limbe, for this study is highly appreciated. Dr Martin Cheek, Royal Botanic Gardens, Kew is thanked for his helpful comments on an earlier draft of this paper. Finally, we are also grateful to the anonymous referees.