Research Article |
Corresponding author: Paul Wilkin ( p.wilkin@kew.org ) Academic editor: Sandy Knapp
© 2015 Paul Wilkin, A. Muthama Muasya.
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:
Wilkin P, Muasya AM (2015) Clarifying the Dioscorea buchananii Benth. species complex: a new potentially extinct subspecies for South Africa. PhytoKeys 48: 51-72. https://doi.org/10.3897/phytokeys.48.6806
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The Dioscorea buchananii complex is shown to comprise three species, one of which is divided into two subspecies, based on morphological data. Two species, D. rupicola Kunth and D. multiloba Kunth, are endemic or subendemic to South Africa and of widespread occurrence in KwaZulu Natal. They differ markedly from each other in inflorescence and floral morphology and appear to be ecologically differentiated. The third species, D. buchananii Benth., is primarily found in southeastern tropical Africa, but a small number of specimens collected in South Africa in the late 19th and early 20th centuries are placed in an endemic subspecies, D. buchananii subsp. undatiloba (Baker) Wilkin. The latter taxon is a high priority in terms of rediscovery and conservation. Keys, descriptions, supporting information and illustrations are provided and made available online through eMonocot biodiversity informatics tools. Three nomenclatural acts are undertaken: two names are placed in synonymy and a new combination made.
Africa, South Africa, Dioscorea , yam, species, taxonomy, vines, conservation, steroids, eMonocot scratchpad
The Dioscorea buchananii Benth. group of species first came to the attention of science through the publication of three species with palmately lobed leaves from South Africa that had been collected by some of the early botanical explorers of the Cape: D. diversifolia Kunth, D. multiloba Kunth and D. rupicola Kunth (
Archibald (1968) covered only Eastern Cape specimens and populations of D. rupicola in her account of Cape Dioscorea. Von Teichman (
The taxa of the D. buchananii complex share perennial, subterranean tubers, left-twining habit, a tendency to possess palmately lobed leaves (but with entire leaves in some to many populations), relatively short spicate to racemose inflorescences, paired floral bracts and flowers with well-developed receptacles and seeds that are winged all round the margin but with a wing that is longer than wide (often oblong-elliptic). The comments reported above by Knuth and von Teichman suggested that there are fewer morphological entities than species currently recognised;
The results and revised classification presented below are based on study of specimens at the following herbaria B (images), BOL, BM, K, P, PCE, PRE, NU (images) OXF, TCD and WAG and for D. buchananii COI, LISC, LMU, MAL and SRGH and include character data previously published in
Floral morphology indicates that there are three taxonomic entities in the D. buchananii species complex, not one as reported in
The principal characters differentiating D. rupicola, D. multiloba and D. buchananii and their states in seven critical South African specimens. All measurements in mm.
D. rupicola | D. multiloba | D. buchananii | Junod 1416 (K sheet) | Junod 2182 | Breyer in TM23387 | Medley Wood 11673 | Medley Wood 12969 | Gerrard & McKen 1617 | Pole Evans 4854 | |
---|---|---|---|---|---|---|---|---|---|---|
Leaf margin | (3-) 5(-7) shallow to deep basal lobes, very rarely entire | Entire to with 3, 5 or 7 shallow to deep lobes often towards blade base | Entire to with 3, 5 or 7 shallow to rarely deep lobes towards blade base | 3 or 5 basal lobes, weak secondary lobing primarily on central lobe | 3, 5 or 7 basal lobes, weak secondary lobing primarily on central lobe | Deeply 5 or 7-lobed, with irregular secondary lobing especially on central lobe margins | Palmately 5 or 7-lobed with irregular secondary lobing on each lobe | Palmately 5 or 7-lobed with irregular secondary lobing on each lobe | Palmately 5 or 7-lobed with irregular secondary lobing on each lobe | 3 or 5 shallow to deep basal lobes |
♂ infl. length | 20–86 | 10–88 | 16–70 | 14–42 | 14–32 | 15–34 | 5–12 | 10–33 | 24–28 | 6–21 |
♂ infl. habit | Erect | Pendent to spreading | Pendent to spreading | Pendent | Pendent | Pendent to spreading | Pendent | Pendent to spreading | Pendent to spreading | Pendent |
♂ infl. flower organisation on axis | Solitary | Solitary or rarely in clusters of 2-3 | Solitary or rarely in cymules of 2–3 flowers | Solitary or rarely in cymules of 2–3 flowers | Solitary or rarely in cymules of 2–3 flowers | Solitary or rarely in cymules of 2–3 flowers | Solitary | Solitary | Solitary | Solitary |
♂ floral orientation | Pendent on axis via recurved pedicels | Patent to axis | Patent to pendent axis | Patent to pendent axis | Patent to pendent axis | Patent to pendent axis | Patent to pendent axis | Patent to pendent axis | Patent to pendent axis | Patent to pendent axis |
♂ & ♀ tepals at anthesis | Erect to ascending | Spreading | Spreading | Spreading | Spreading | Spreading | Spreading | Spreading | ♀ spreading, ♂ post anthesis | Spreading |
♂ flowers pedicel length | 0.6–1.5 | (Sub)sessile | 2.0–5.0 | 1.9–3.4 | 1.7–2.3 | 2.7–3.5 | 1.9–3.0 | 1.9–2.3 | 2.1–3.7 | 0.15–0.5 |
♂ Outer tepal L × W | 2.0–3.8 × 0.6–1.3 | 1.4–2.1 × 0.7–1.5 | 2.5–4.7 × 1.1–2.3 | 2.9–3.6 × 1.9–2.1 | 2.3–3.3 × 1.8–2.2 | 2.5–3.7 × 1.3–1.8 | 2.7–3.7 × 1.3–1.6 | 2.3–3.2 × 1.4–2.0 | 2.5–3.0 × 1.1–1.3 | 1.9–2.7 × 1.6–1.9(–2.3) |
♂ Inner tepal L × W | 2.0–3.7 x0.8–1.5 | 1.2–2.2 × 0.7–1.3 | 2.7–4.5 × 1.3–2.3 | 3.0–3.7 × 1.7–2.1 | 2.3–3.4 × 1.4–1.7 | 2.9–3.2 × 1.5–1.8 | 2.6–3.3 × 1.0–1.8 | 2.5–2.9 × 1.3–1.8 | 2.5–3.0 × 1.1–1.3 | 1.9–2.9 × 1.6–2.5 |
♂ torus diam. | 1.0–2.1 | 1.5–2.3 | 2.3–5.0 | 2.5–3.1 | 2.3–3.1 | 2.2–3.1 | 1.9–3.4 | 2.2–2.9 | 1.5–1.9 (post–anthesis/withered) | 2.7–3.3 |
Stamen no. | 3 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | Unknown | 6 |
Filament L | 0.5–1.0 | 0.35–0.7 | 0.6–1.8 | 1.0–1.6 | 0.8–1.3 | 0.7–0.8 | 1.1–1.6 | 0.9–1.1 | N/A | 0.5–0.7 |
Anther L × W | 0.25–0.35 × 0.25–0.35 | 0.3–0.5 × 0.2–0.45 | 0.5–1 × 0.4–0.8 | 0.6–0.7 × 0.3–0.5 | 0.5–0.7 × 0.3–0.5 | 0.7–0.8 × 0.3–0.7 | 0.9–1.2 × 0.6–0.9 | 0.7–0.8 × 0.4–0.7 | N/A | 0.5–0.6 × 0.25–0.35 |
♀ tepal L × W | 2.3–3.1 × 0.7–1.7 | 1.5–2.5 × 0.8–1.5 | 2.9–4.5 × 0.8–2.0 | N/A | 2.6–3.2 × ca 1.4 | N/A | N/A | N/A | 1.9–3.2 × 0.9–1.1 | N/A |
♀ Torus diam. | 1.8–2.5 | 1.7–2.4 | 2.5–4.5 | N/A | Ca 2.9 | N/A | N/A | N/A | 2.7–3.3 | N/A |
Capsule L × W | (18–)20–30 × 13–20 | 16–28 × 15–20(–22) | 22–30 × (13–)18–32 | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
Seed wing L × W | 10.5–18.8 × 6.7–8.3 | 11–14 × 6.5–9.3 | 10–20 × 7–13 | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
Seed L × W | 4.6–6.5 × 5.0–6.5 | 4.6–5.0 × 3.7–5.0 | 2.5–4 × 3–4 | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
During the study, six specimens from South Africa were encountered that possessed inflorescence and floral morphology similar to that of D. buchananii but whose leaves had at least a degree of secondary (pinnatifid) marginal lobing, especially on the central primary lobe (Figure
Dioscorea buchananii subsp. undatiloba vegetative and reproductive morphology A Habit of male plant with axillary inflorescences B Apical part of male inflorescence showing tepal shape and habit and bud shape C Rehydrated male flower with apical part of pedicel showing stamen morphology (NB tepal and stamen habit influenced by specimen preparation) D Fully opened out rehydrated male flower from above showing tepal shape, torus and pistillode E Female flower with ovary at late anthesis, tepals ascending F Female flower with 3 tepals removed showing torus, staminodia and gynoecium G Immature capsule with pedicel, floral bract and persistent tepals at apex H Leaf of KwaZuluNatal form of Dioscorea buchananii subsp. undatiloba. Scale bar: A, H 3 cm; B 7 mm; C, D, E 5 mm; F 3 mm; G 2 cm. From Breyer in TM 23387 (A), Junod 2182 (B, G), Medley Wood 11673 (C, D) Gerrard & McKen 1617 (E, F) Medley Wood 12969 (H). Drawn by Lucy Smith.
1 | Stamens 6, inflorescences spreading to pendent, tepals spreading, apices flat | 2 |
– | Stamens 3, inflorescences erect, and bearing flowers patent to axis to recurved towards its base, tepals erect to ascending, apices cucullate | D. rupicola |
2 | Flowers subsessile, tepals 1.2–2.2 m long, buds (sub)globose | D. multiloba |
– | Flowers on 1.7–5.0 mm long pedicels, tepals 2.3–4.7 mm long, buds turbinate | 3 |
3 | Leaves entire to moderately lobed at stem base and on vegetative stems but then less strongly lobed to entire on reproductive shoots, lobe margins at most weakly undulate | D. buchananii subsp. buchananii |
– | Leaves consistently moderately to deeply 3, 5 or 7-lobed from stem bases to apices, with irregular, pinnate secondary lobing present on central lobe at least | D. buchananii subsp. undatiloba |
1 | Floral torus diameter 2.5–4.5 mm. Capsule oblong to obovate to very broadly so or rotund in outline, capsule width (13–)18–32 mm | 2 |
– | Floral torus diameter 1.7–2.5 mm. Capsule oblong to narrowly obovate in outline, capsule width 13–20(–22) mm | 3 |
2 | Leaves entire to moderately lobed at stem base and on vegetative stems but then less strongly lobed to entire on reproductive shoots, lobe margins at most weakly undulate | D. buchananii subsp. buchananii |
– | Leaves consistently moderately to deeply 3, 5 or 7-lobed from stem bases to apices, with irregular, pinnate secondary lobing present on central lobe at least | D. buchananii subsp. undatiloba |
3 | Tepals erect, staminodia 3 | D. rupicola |
– | Tepals spreading, staminodia 6 | D. multiloba |
Dioscorea buchananii Benth., Hooker’s Icon. Pl. 14:76, t. 1397, 1398 (1882).
Dioscorea buchananii var. ukamensis R.Knuth in H.G.A Engler (ed.), Pflanzenr. 4, 43: 185 (1924). Type: Tanzania, Morogoro Dist., Ukami, without date, Stuhlmann 8283 (holotype: B†).
D. mildbraediana R.Knuth, Notizbl. Bot. Gart. Berlin-Dahlem 11: 1059 (1934).
Type: Tanzania, Kilwa, Mswega, ♂ fl. 22 Jun 1932, Schlieben 2495 (holotype: B!; isotype BR!).
D. rhacodes Peter ex R.Knuth, Repert. Spec. Nov. Regni Veg. 42: 162 (1937).
Type: Tanzania, Ukami, east of Morogoro, ♂ fl. 1926, Peter 46419 (holotype: B!).
Malawi: Shire Highlands, ♂ fl. 1881, Buchanan 173 (syntype: K!) ♀ fr. 1881, Buchanan 358 (syntype: K!).
Twining vine to 10 m in height, vegetative growth annual, usually 1 shoot per year from apex of perennial, woody tuber, to ca 20 cm in diam., usually globose to ovoid, sometimes elongate or irregular, shape varying perhaps based on rockiness of substrate, externally dark grey to brown, fissured, bark-like. Indumentum absent. Stems left-twining, to 5 mm in diam., terete to shallowly longitudinally ridged, more so when dry, unarmed from base, green or purple-hued, herbaceous, cataphylls not seen. Leaves alternate, blade variable, 2.8–13.5 × 1.1–14.7 cm, entire or with 3, 5 or 7 shallow to deep lobes, ovate to broadly so, veins 7(–9), primary venation in shallow channels on upper surface in fresh material, primary and secondary venation prominent below, base cordate, with a shallow to deep basal sinus, rarely truncate, texture chartaceous, where lobes present central lobe to 116 mm long, lateral lobes to 35 mm long, lobes usually found primarily in vegetative stem leaves with reproductive stem leaves more weakly lobed to entire, rarely consistently lobed to shoot apices, lobes inserted from around mid-point to point of petiole insertion, lobe margins entire to (rarely) weakly undulate or in some leaves lobed to stem apices with weak to strong irregularly pinnate secondary lobing, blade or central lobe apex acute to triangularly short-acuminate, rarely obtuse or truncate, bearing a 1.5–10 mm long, thickened, very narrowly triangular, brown forerunner tip fed by the 3 central veins of blade; petiole 0.6–6.3 cm long, ridged like stem and with a narrow channel on upper surface, colour as stem, pulvinii sometimes paler or purple-hued; lateral nodal organs absent but petiole base broader where inserted onto stem, axillary bulbils absent. Inflorescences simple, usually 1 per axil, axes straight, angular, pale green or purple or brown-hued; male 1.6–7 cm long, peduncle 2–11 mm long, racemose, pendent to spreading, usually dense with flowers 0.3–4.1 mm apart and solitary or rarely in cymules of 2–3 flowers, on a 1.7–5.0 mm long pedicel that is angular and slightly broader towards apex, buds patent to axis, pendent at developing inflorescence apex only in very early development; female inflorescence 9–77 mm long, accrescent to ca 30 cm long in fruit, peduncle 12–20 mm long, spicate, pendent, lax, flowers subpendent only at the earliest stages of development, patent to axis at anthesis but ascending to erect soon thereafter. Flowers turbinate in bud, tepals 6, free, inserted on margin of a saucer-shaped, weakly thickened torus, spreading at anthesis, sometimes ascending thereafter, whorls scarcely differentiated, 3–veined, brown, green, olive or bronze, sometimes with a pink or yellow hue or mottled; male flower with floral bract and bracteole sheathing pedicel base, bract 1.6–2.6 mm long, ovate, long-acuminate, membranous, bracteole similar, narrower, usually offset from bract; outer tepals 2.5–4.7 × 1.1–2.3 mm, inner tepals 2.7–4.5 × 1.3–2.3 mm, narrowly ovate to lanceolate or triangular, chartaceous, apex acute to short–acuminate, flat; filaments 0.6–1.8 mm long, erect but incurved over 2.3–5 mm diam. torus, anthers 0.5–1.2 × 0.4–0.8 mm, introrse; pistillode to ca 0.1 mm high, 3 centrally fused triangular ridges at 120° to each other in flat central part of concave torus; female flower with floral bract and bracteole sheathing ovary base, bract 1.6–2.4 mm long, ovate, long-acuminate, membranous, bracteole similar, narrower, usually offset from bract; ovary 5–10 mm long, 3-angled, lorate to very narrowly elliptic in outline, colour as axis, apex constricted; outer tepals 2.9–4.5 × 0.8–1.9 mm, inner tepals 2.9–4.4 × 0.9–2 mm, more or less erect, narrowly ovate to lanceolate, apex acute to short-acuminate, flat, each tepal with 0.2–0.7 mm long basal staminode inserted at the boundary with the torus at the tepal base midpoint, usually fleshy and ovoid but sometimes substaminiform; torus 2.5–4.5 mm in diam. both tepals and torus accrescent as ovary enlarges; style 1.8–3.2 mm long, erect, divided into 3 spreading branches towards apex, stigmas bifid, oblong to clavate. Capsule 2.2–3 × (1.8–)2–3.2 cm, pedicel reflexed and thus ascending to erect at dehiscence, lobes obovate to oblong-obovate in outline, thick-chartaceous, base and apex usually truncate, dry and withered flowers persistent until relatively late in development on a ca 1.2–2.0 mm long stipe, light brown with chestnut-brown to coppery brown mottling, dehiscing apically at least at first. Seed 2.5–4 × 3–4 mm, irregularly lenticular, dark brown wing 1–2 × 0.7–1.3 cm, broadly oblong-elliptic to rotund to irregularly so, wing extending all around seed margin although elongated towards rounded to obtuse base and apex, pale brown, translucent with fine paler speckling.
Leaves entire to moderately 3, 5 or 7-lobed at stem base and on vegetative stems but then less strongly lobed to entire on reproductive shoots, lobe margins at most weakly undulate; where lobed central lobe usually the largest, maximum length as in species as a whole, broadly ovate to lanceolate or deltoid, lateral lobes oblong to rounded. Male flower pedicel, tepal and torus dimensions as in species as a whole.
Tanzania and Southern and Eastern Congo (Kinshasa) to southern Mozambique, Zimbabwe and Angola.
See
Frequently associated with rocky habitats, often in Brachystegia woodland, but also on termitaria, in riverine forest and near mangrove swamps, on limestone and granite substrates; sea level to 1600 m (
The broad southeastern African distribution of this species indicates that its EOO and AOO will greatly exceed the threshold for threatened IUCN categories (20, 000 km2/2000 km2) (
None known.
Representative specimens are cited in
Dioscorea undatiloba Baker, J. Bot. 27: 8 (1889); R.Knuth in H.G.A Engler (ed.), Pflanzenr. 4, 43: 184 (1924).
Type: South Africa. KwaZulu Natal: Port Natal, Mandini District, Tugela, ♂ fl. & ♀ fl. without date, Gerrard & McKen 1617 (holotype: K post anthesis ♂ fl. & ♀ fl. [K000098906!]; isotype: TCD!, ♀ fl.!)
Dioscorea junodii Burtt-Davy, Kew Bull. 1924: 231 (1924), synon. nov.
Type: South Africa. Limpopo: Mopani District, Valley of Schambock’s Stadt, near Shilouvane, (Shiluvane) Sanatorium, 24°02'20"S, 30°16'59"E, ♂ fl. Junod 1416 (holotype: K [K00098905!]), non PRE [PRE0093186-0, digital image!]
Based on Dioscorea undatiloba Baker.
Leaves consistently moderately to deeply 3, 5 or 7-lobed from stem bases to apices, with irregular, pinnate secondary lobing present on central lobe at least; central lobe to 50 mm long, lanceolate to elliptic or rhomboid, lateral lobes to 33 mm long, oblong to narrowly so, central lobe largest to lobes more or less equal in length and width. Male flowers on 1.7–3.7 mm long pedicels, tepals 2.3–3.7 × 1.0–2.2 mm, torus (1.5–)1.9–3.4 mm in diam.
Endemic to South Africa in Limpopo and KwaZulu Natal provinces. The Limpopo specimens are from localities relatively close to those of the type subspecies in Gaza province of Mozambique.
Not known.
Ca. 50 to 600 m altitude in KwaZulu Natal, and 700 to 1000 m in Limpopo. Associated geology, soils and vegetation unknown.
Dioscorea buchananii subsp. undatiloba has not been recorded since 1921 in either Limpopo or KwaZulu Natal and is known from only six specimens. However, pending urgently needed searches to find extant populations in Limpopo, KwaZulu Natal and the intervening areas and further research on the relationships between those populations, the most appropriate provisional conservation status assessment is DD. It is conceivable that this taxon is already extinct in part or all of its range, especially extensively developed lowland KwaZulu Natal.
None known
The specimen labelled Junod 1416 at PRE [PRE0093186-0] is male flowering material of D. sylvatica Ecklon. This explains the placement of D. junodii in the synonymy of that species in
South Africa. Limpopo: Mopani District, Shiluvane, 24°02'20"S, 30°16'59"E, ♂ fl. & ♀ fr. May 1905, Junod 2182 (Transvaal Museum 7164), (PRE!); Louis Trichardt, ♂ fl. Jan 1921, Breyer in TM (Transvaal Museum) 23387 (K!, PRE). KwaZulu Natal: uThungulu District, Umvuzaan (uMvuzane) Valley, 28°46'21"S, 31°20'29"E, ♂ fl. buds Jan 1915, Medley Wood 12969 (K!); Pietermaritzburg, Camperdown 29°43'59.91"S, 30°31'59.87"E ♂ fl. Mar 1910, Medley Wood 11673 (K!).
Dioscorea multiloba Kunth, Enum. Pl. 5: 376 (1850); R.Knuth in H.G.A Engler (Ed.), Pflanzenr. 4, 43: 183 (1924).
Dioscorea diversifolia Kunth, Enum. Pl. 5: 375 (1850), non Griseb. in C.F.P.von Martius (Ed.), Fl. Bras. 3(1): 41 (1842), type only.
Type: South Africa. Eastern Cape: Pondoland, between Umtentu and Umzimkulu Rivers, ♂fl. & ♀ fr., Feb, year unknown, Drège 4497 (holotype: B [B_10_0278736 ♂fl. digital image!]; isotypes: G [G00018717 ♂fl. digital image!]; K [K000098903,K00098904 ♂fl. & ♀old fr.!]; OXF [OXF0004195 ♂fl. & ♀ old fr.!]; P [P00440190! ♀ fr.!]; TCD ♂fl.!).
Dioscorea natalensis R.Knuth in H.G.A Engler (ed.), Pflanzenr. 4, 43: 94 (1924), synon. nov.
Type: South Africa. KwaZulu Natal: Durban [Kingsburgh], Winkle Spruit, ♂fl. 28 Feb 1912, Rudatis 1609 (holotype: B [B_10_0160974 digital image!]; isotypes K! [K000815875, K000815874] WAG [WAG0027134!]; Z [Z-000065671, Z-000065672, digital images!].
Dioscorea digitaria R.Knuth in H.G.A Engler (ed.), Pflanzenr. 4, 43: 184 (1924).
Type: South Africa. KwaZulu Natal Friedenau, Umgayeflat (Alexandria), ♂fl. 1 Oct 1909, Rudatis 724 (holotype: B [B_10_0160991 digital image!]).
South Africa. KwaZulu Natal: “Probably collected in Pondoland”, ♂ fl. & ♀ fr. 1840, Drège 4496 (lectotype: K! [K000098902 ♂fl. buds & ♀ fr.]; isolectotypes B [B_10_0004142 ♂fl. buds & ♀ fr., B_10_0004143 ♂fl. buds digital images!]; G [G00018675♀ fr. digital image!]; K [K000098900 ♂fl. buds & ♀ fr.!]; KIEL; OXF! [OXF00004193♀ fr.]; P [P00440187 ♀ fr., P00440188 ♂fl. buds & ♀ fr., P00440189 ♀ fr., P00440191 ♂fl. buds & ♀ fr.!], TCD ♀ fr.!).
Twining vine to ca 3 m in height, vegetative growth annual from a perennial tuber. Tuber apex only seen, ca 15 cm in diam., convex, dark brown to black, bark-like, bearing one shoot per year at central apex, according to
Dioscorea multiloba Kunth vegetative and reproductive morphology. A Habit of male plant with axillary inflorescences B Apical part of male inflorescence showing tepal shape and habit and bud shape habit C Lobed leaf showing venation of upper surface and forerunner tip D Male flower from above showing filament habit E Male flower with 3 tepals and part of torus removed showing torus shape, pistillode and associated concavities in torus surface F Female flower with 3 tepals and part of torus removed showing torus shape, staminodia and gynoecium G Female inflorescence showing tepal habit and ovaries H Infructescence showing some submature capsules with persistent tepals J Seed showing wing shape. Scale bar: A, C 3 cm; B 7 mm; D, E 4 mm; F 3 mm; G, H 2.5 cm; J 2 cm. From Ward 3076 (A, B, D, E), Medley Wood 329 (F, G), Gueinzius s.n. (H, J) and a photograph (C). Drawn by Lucy Smith.
Dioscorea multiloba and Dioscorea rupicola colour photographs. A Upside down shoot of D. multiloba with male flowers B Female plant of D. multiloba with female flowers and immature capsules C Leaf and erect male inflorescence of D. rupicola showing habit of flowers. D Immature capsule of D. rupicola with persistent, erect, cucullate tepals at its apex. Photo A, B: Tony Abbott; C, D: Neil Crouch.
Endemic to South Africa (Eastern Cape to Mpumalanga) and Swaziland.
The only vernacular name known is wild yam.
Dioscorea multiloba occurs in a range of habitats but is principally associated with forest and bush margins and associated grasslands on a range of sandy and loamy substrates. In the northern part of its range it often appears to occur in swampy habitat. It is found at altitudes from close to sea level to 800 m in KwaZulu Natal. At the edges of its range the specimen from Swaziland (Compton 26691) was collected at ca 4000’ (1200 m) and Flanagan 2717 from the Eastern Cape 4500’ (1400 m).
Dioscorea multiloba is widespread in lowland KwaZulu Natal, and its distribution extends into the Eastern Cape, Mpumalanga and Swaziland. Thus its EOO and AOO will greatly exceed the threshold for threatened IUCN categories (20, 000 km2/2000 km2) (
None known. Data on the steroid content of this species is desirable.
Kunth cites male and female syntypes as follows “Drège, Herb. Cap. no. 4495. ex parte. v.s. in Herb. Luc. and Drège, Herb. Cap. No 4496. ex parte. v.s in Herb. Luc.” Herb. Luc. appears to be an abbreviation for Herbarium Lucae, which formed part of the KIEL herbarium. Kunth specified that 4495 was male and 4496 female. However, there is both male and female material at K under 4496. In contrast, a single sheet in B (B_10_0004142) has fragments of both male and female plants under both collection numbers. P has female material under 4495 (P00440190) and male material under 4496 (P00440188) among 5 duplicates of both numbers. Given this confusion and the number of duplicates in European herbaria it was decided to lectotypify the species using K000098902, the most complete and representative specimen available.
The only specimen cited in the protologue of Dioscorea diversifolia Kunth, a later homonym of D. diversifolia Griseb., was Drège 4497. The material under this number at TCD appears to represent two different male plants of D. multiloba, with the left and bottom fragments possessing flexuous inflorescences and the right a straight inflorescence. The K and OXF material is different, with entire leaves, male flowers in bud and the previous season’s fruit. K has 2 very similar sheets from both Hooker and Bentham’s herbaria.
South Africa. Eastern Cape: Komga, near Kei Mouth, ♂ fl. Jan 1890, Flanagan 442 (K!, PRE); Engcoba (Ngcobo) Mountain, ♀ immature fr. Jan 1896, Flanagan 2717 (PRE!); Mquanduli, Coffee Bay, ♂ fl. 4 Mar 1953, Theron 1505 (PRE!); Pondoland, between Umtentu River and Umzinkulu River, ♂ fl.buds & old fr. Feb unknown year, Drège 4497 (K!, OXF!, TCD!). KwaZulu Natal: Port Shepstone, Mgayi, 30°25'S, 30°30'E, ♂ fl. 27 Jan 1968, Ward 6339 (NU [NU0028305], UDW); Port Shepstone, Mgayi, “30°25'S, 30°25'E”, ♀ immature fr. 27 Jan 1968, Ward 6340 (K!, NU [NU0028304 digital image!], PRE, UDW digital image!); Inanda, ♀ fl. & immature fr. Jan ?1879, Medley Wood 329 (K, 2 sheets!); Port Shepstone, Umtamvuna Nature Reserve, Beacon Hill, 31°00'33"S, 30°10'55"E, ♀ fl. & immature fr. 9 Dec 2010, Abbott 9287 (PCE!, PRU!); Port Shepstone, Umtamvuna Nature Reserve, Beacon Hill, 31°00'33"S, 30°10'55"E, ♂ fl. 9 Dec 2010, Abbott 9288 (PCE!, PRU!); Inanda, ♂ fl. Jan. ?1880, Medley Wood 825 (K!); Inanda, Groenberg, ♂ fl. Mar ?1880, Medley Wood 892 (K!); Lions River District, collected at Karkloof 11 July 1952 and cultivated at Irene, ♀ immature fr. 20 Dec 1954, Pole-Evans 4862 (K!, PRE); Durban, Umbilo Waterfall, ♂ fl. received Feb 1883 Rehmann 8155 (K!); Port Natal, ♂ fl. & ♀ fr. without date, Gueinzius s.n. (K!; TCD!); Port Natal, ?Umgena, ♂ fl. without date, Gerrard & McKen 1920 (TCD!); Fort Bowker, ♂ fl. & ♀ fr. without date, Bowker 575 (TCD!); Kaffraria, Tsomo (?), ♂ fl.. without date, Bowker 861 (TCD!); Fort Bowker ♂ fl. without date, Bowker 627 (TCD!); Natal, no further data, ♂ fl. without date, Gerrard & McKen 36 (TCD!); Port Natal, ♂ fl. without date, Sanderson 5 (TCD!); Durban District, Umbogintwini, above lagoon, st. 10 May 1964, Ward 4976 (NU [NU0028355 digital image!]); Pietermaritzburg District, Isipingo Flats, 29°59'S, 30°56'E ♂ fl. 1 May 1971, Ward 6992 (NU [NU0028390 digital image!], UDW digital image!); Lower Umfolozi District, Hluhluwe Game Reserve, ♂ fl. 24 Jan 1949, Ward 665 (NU [NU0028255, 0028351 digital image!]); Hlabisa District, Hluhluwe Game Reserve, ♂ fl. 16 Jan 1954, Ward 2073 (K!, NU [NU0028352 digital image!], PRE); Hlabisa District, Hluhluwe Game Reserve, ♂ fl. 6 Mar 1957, Ward 3076 (K!, (NU [NU0028353, 0028354 digital images!], PRE); Mtubatuba District, Hlabisa, Park Ridge Farm, ♀ fr. 11 May 1968, Harrison 498 (PRE!); Maputaland, Kosi Bay area near Catholic Mission, sterile 20 Mar 1965, Vahrmeijer 482 (K!, PRE); Maputaland, 3 miles from Maputa on road to Olibotini, ♂ fl.23 Mar 1965, Vahrmeijer 540 (K!, PRE); KZN, No further data, ♂ fl. received Jul 1965, Gerrard 772 (K!); ♂ fl. received Jul 1965 & Mar 1872, Gerrard 1920 (K!); KZN, Locality illegible, ♂ fl. 1862, Cooper 3244 (K!). Mpumalanga: Pilgrims Rest District, collected at Mac Mac 19 Aug 1952 and cultivated at Irene, ♂ fl. 20 Dec 1954, Pole-Evans 4846 (K!, 2 sheets, PRE); Pilgrims Rest District, collected at Mac Mac and cultivated at Irene, ♂ fl. 14 Apr 1955, Pole-Evans 4861 (K!, 2 sheets, PRE). Swaziland: Mankaina District, ♂ fl. 3 Feb 1958, Compton 27492 (K!, PRE); Mbabane District, Ukutula, ♂ fl. 21 Feb 1957, Compton 26691 (K!, PRE).
Dioscorea rupicola Kunth, Enum. Pl. 5: 378 (1850).
SOUTH AFRICA. No further data, plant obtained by Ecklon possibly from the Winterberg mountains cultivated in Berlin s.n., ♂ fl. 27 Jul 1836 (holotype: B†; isotype K! [K000098907!]).
Twining vine to not more than 5 m in height. Vegetative growth annual from a perennial tuber. Mature tuber apex to 4 × 4 cm, buried to 15 cm below soil surface, irregularly ridged longitudinally, corky, with an apical depression bearing shoot(s, usually 1 per year) and hard, brown, deltoid cataphylls to 15 mm long; base of tuber bearing 1–3 branches to 30 × 1– 3 cm long, corky and fissured externally and bearing wiry roots, parenchyma white, brittle (fide Archibald 1968). Indumentum absent. Stems to 4 mm in diam., left-twining, terete but longitudinally ridged, unarmed, pale green, sometimes pink, purple or brown-hued, branched above, cataphylls present towards base, to 6 × 3 mm, deltoid, apex caudate, recurved (fide Archibald 1968). Leaves alternate, blade 20–104 × 15–85 mm, ovate to narrowly so or lanceolate in outline, weakly to strongly 3- to 7-lobed around point of petiole insertion, rarely entire, juvenile plants with wholly entire leaves, usually broadly ovate to orbicular, texture chartaceous (thinner in juveniles), primary venation in shallow channels on upper surface in fresh material and lamina between secondary veins weakly bullate, shiny mid green above, paler below, drying olive green below, browner above; margins weakly undulate in fresh material, base cordate, sinus (1–)3–33 mm deep, lobes to 36 mm long, apically obtuse to rounded, apical lobe lanceolate to lanceolate-deltoid or lanceolate oblong, apex broadly acuminate with a 0.5–5 mm long narrow, caudate, thickened forerunner tip that appears channelled above, brown, veins usually 7, 3 in apical lobe with 2 per side running into basal lobe(s), sometimes a smaller vein close to the basal sinus, primary and secondary venation prominent below; petiole 10–67 mm long, ridged and with a narrow channel on upper surface, colour as stem, basal pulvinus flattened and broadly deltoid towards point of insertion onto node, especially in larger leaves, lateral nodal organs absent but in largest stems nodes swollen with a blunt projection on either side of petiole insertion onto node; axillary bulbils not present. Inflorescences 1 per axil, simple, axes angular, pale green, flowers campanulate; male inflorescences 20–86 mm long, peduncle 5–14 mm long, ca 1 mm in diam. at base, racemose, erect and bearing flowers ca 2–8 mm apart, buds oriented towards apex in very early development but at least patent to axis and usually recurved towards its base at anthesis, female inflorescences 9–82 mm long, peduncle 9–24 mm long, spicate, pendent, flowers oriented towards apex in very early development but usually patent to axis to ascending at anthesis. Flowers with 6 tepals, buds turbinate, apex acute-conical, at anthesis pedicel, tepals and torus exterior pale green to yellow-green, torus inner surface light pink to purple, possessing a light, sweet fragrance (fide Moll 1400, Archibald 1968); male flowers borne on 0.6–1.5 mm long curved, stout, obconic pedicels, floral bract 1 per flower, at pedicel base 1.0–1.7 × 0.4–0.7 mm long, ovate to narrowly so, acuminate, concolorous with pedicel and flower when fresh, paler brown than flower when dry; bracteole 1 per flower, similar, usually narrower and slightly shorter; tepal whorls virtually undifferentiated, inner slightly broader, tepals free, outer whorl 2.0–2.8 × 0.6–1.3 mm, inner whorl 2.0–3.7 × 0.8–1.5 erect to ascending, lanceolate to deltoid-lanceolate, apex acute but cucullate and appearing blunt, tepals inserted on the margin of a 1.0–2.1 mm diam. fleshy torus, when fresh externally broadly convex, internally with 3 swollen lobes forming an annulus with a central depression in flower centre, shape lost in drying but darker than tepals; stamens 3; filaments 0.35–0.7 mm long, inserted at base of each torus lobe on outer edge adjacent to outer whorl tepals, erect, weakly incurved, pale green, anthers 0.25–0.35 × 0.25–0.35 mm, very broadly oblong-orbicular, introrse, basifixed, pale yellow; pistillode ca 0.1 mm long, conical; female flowers overall shape as male, sessile, floral bract 1.0–2.0 × 0.6–1.2 mm, ovate to broadly so, acuminate, concolorous with inflorescence axis, bracteole narrower and thinner, both erect and appressed to ovary base; ovary 3.8–9.1 mm long, 3-angled, lorate to very narrowly elliptic in outline, pale green, sometimes purple-hued, apex weakly constricted, tepals 2.3–3.1 × 0.7–1.7 mm, shape and habit as male, inserted on the margin of a 1.8–2.5 mm diam. fleshy torus, when fresh forming an annulus in centre of flower bearing 3 0.1–0.7 mm long staminodia opposite outer tepals; style inserted in central depression, 0.9–1.2 mm long, styles 3, spreading, bifid, gynoecium concolorous with tepals. Capsule (18–)20–30 × 13–20 mm, pedicel reflexed and thus more or less erect at dehiscence, oblong-elliptic to obovate in outline, thick-chartaceous, base obtuse, apex rounded to truncate, dry and withered flowers persistent until relatively late in development (early April) on a ca 1.5–2 mm long stipe, pale brown with darker coppery-brown speckling, dehiscing apically at least at first. Seed 4.6–6.5 × 5.0–6.5 mm excluding wing, irregularly lenticular, dark brown, wing 10.5–18.8 × 6.7–8.3 mm, oblong to oblong-elliptic, winged all round margin though with elongated towards rounded to obtuse base and apex, pale brown, translucent with fine paler speckling.
South Africa, endemic to the Eastern Cape (as far west as the Winterberg) and KwaZulu Natal.
Cunningham 2486, a sterile specimen grown from a root bought at Umlazi Muthi market appears to be D. rupicola and has the name iMpinyampinya. The name inKwa may also be associated with this species.
D. rupicola grows in the margins of and clearings in forests and bush (including Leucosidea sericea woodland) and is often associated with watercourses and rocky kloofs. Archibald (1968) stated that it occurs on shady eastern and southern slopes on moist black doleritic soils in association with Podocarpus falcatus and Olea capensis in the Eastern Cape and that it is associated with and dolerite boulders. It is usually encountered from 1200 to 2100 m, but has been collected at lower altitudes in Alexandra District (Rudatis 1269, 600 m) and Umzinto District (Strey 7052, ca 580 m) in KwaZulu Natal.
D. rupicola is found widely in higher elevation sites in the Eastern Cape and KwaZulu Natal. Its EOO and AOO will greatly exceed the threshold for threatened IUCN categories (20, 000 km2/2000 km2) (
None known. Like D. multiloba, data on the steroid content of this species is desirable.
The specimens bearing labels Dioscor. 3, Ecklon & Zeyher 21.12 at TCD (♂ fl.) and LE (seen by Prain in 1916 according to a note on the Kew isotype) appear likely to have made from the plant material that was taken to Berlin and cultivated to yield the type. Alternatively it is possible that they were collected from other plants with that seed or tuber in late 1831 or early 1832. The locality 21.12 suggests that the collection was made in the Winterberg mountains in the Eastern Cape (
Unpublished sequence data shows that D. rupicola forms a clade with the other two species covered here. Thus the shift in androecium morphology is likely to be a recent, pollinator-driven event correlated with the erect inflorescences bearing recurved flowers with erect to ascending tepals (Fig.
South Africa. Eastern Cape: Winterberg Mountains, ♂ fl. late 1831 or early 1832, Ecklon & Zeyher s.n. (TCD!, LE) (see Notes above); Collected at Mt. Kemp, Keiskamma Hoek and cultivated at Irene, ♀ fl. 20 Dec 1954, Pole-Evans 4847 (K!, PRE); Fort Beaufort District, Hogsback, big dolerite cliff near top of pass facing South, ♂ & ♀ fl. 10 Dec 1961, Archibald 7557 (K!); same locality, ♂ fl. (post anthesis) & ♀ fr. 27 Apr 1962, Archibald 7560 (K!); same locality, ♂ fl. 15 Nov 1961, Archibald 7537 (PRE!); Victoria East, on pass Port Elizabeth aspect, ♂ fl. 15 Nov 1961, Archibald 7551 (K!); Victoria East, about ¼ way up pass, sterile 15 Nov 1961, Archibald 7552 (K!); Victoria East, about ¼ way up pass, ♀ fl. 10 Dec 1961, Archibald 7558 (K!); Hogsback, ♂ fl. 27 Dec 1944, Acocks 11019 (K!); Victoria East, Hogsback Natural Forest Reserve, above Swallowtail Falls, sterile 17 Apr 1955, Johnson 1273 (K!, PRE); King William’s Town District, no further data, ♂ fl. 26 Jan 1956, Comins 1425 (K!, PRE); Mountains near Ntsizwa (in umbros. Mont. Jnsiowa), ♂ fl. 28 Jan 1895, Schlechter 6443 (K!, PRE!, Z digital images!); Insizwa Forest Reserve, sterile 23 Feb 1958, Wilson & Buchner 163 (K!); Insizwa Forest Reserve, sterile seedling 23 Feb 1958, Wilson & Buchner 164 (K!); Insizwa Forest Reserve, sterile seedling 23 Feb 1958, Wilson & Buchner 165 (K!); Insizwa Forest Reserve, sterile seedling 23 Feb 1958, Wilson & Buchner 166 (K!); Insizwa Forest Reserve, sterile seedling 23 Feb 1958, Wilson & Buchner 167 (K!); Insizwa Forest Reserve, sterile 23 Feb 1958, Wilson & Buchner 16 (K!); Kokstad, Tabankulu Forest, ♂ fl. Jan 1925, Dist. Forest Officer 558 (PRE!); Prentjiesberg, Ugie “Forest Reserve”, sterile 12 Nov 2000 Potgieter 392 (NU [NU0028393, 4]). (2 sterile sheets, possibly D. rupicola (28393) and D. multiloba (28394).) KwaZulu Natal: Alfred District, Weza, Ingeli (Ngeli) slopes, 1 Jan 1966, Strey 6284 (K! ♀ fl., (NU [NU0028252 digital image ♂ fl.!], PRE, UDW digital image ♂ fl. !); Alfred District, Ngeli Mountain, ♂ fl. & ♀ fl. 2 Jan 1969, Hilliard & Burtt 5758 (E, K!, NU [NU0028253 digital image!]); Weza State Forest, South boundary of Farm Diabolo, ♂ fl. 3 Dec 1989, Abbott 4583 (NH, PCE!, PRU); Griqualand East, Mount Currie, ♂ fl. Feb- Apr 1883, Tyson 468 (K!, Z digital image!); Griqualand East, Mount Currie, ♀ fr. Feb- Apr 1883, Tyson 1433 (K! Z digital image!); Kokstad, Mt. Currie slopes, ♂ fl. without date, Dist. Forest Officer 636/F.D. Herb 7215 (K!, PRE!); Polela District, Farm “Glengariff”, ♂ fl. late Jan 1981, Rennie s.n. (NU [NU0028254 digital image!]); Polela District Ndunduina Bush, Glengariff, 5 Jan 1974, Rennie 510 (NU [NU0028391 digital image!]); Sunset Farm, 2929DC, ♂ fl. buds 17 Jan 2000, Rennie 2526 (NU [NU0028259 digital image!]); Umzinto District, Ellesmere, ♂ fl. 18 Dec 1966, Strey 7052 (K!, NU [NU0028356 digital image!], UDW, possibly also at PCE (Ellesmere, ? Dumisa, 19 Dec 1966)); Alexandra District, Ellesmere, ♂ fl.20 Feb 1910, Rudatis 1269 (K!); Eastern Frontier C.B.S, Botha’s Hill, ♀ fl. without date, Macowan 537 (TCD!) Weenen, old bush above ‘Lulwers’, ♂ fl. Dec 1923 Rogers 28163 (Z digital image!); York-Rietvlei road, ca 1 km South of Karkloof turnoff, ♂ fl. 17 Jan 1987, Goldblatt & Manning 8362 (MO, NU [NU0028236 digital image!], PRE!); On Road Bulwer to Underberg-SA Paper Pulp Forest, ♀ fl. & immature fr. 22 Feb 1958, Wilson & Buchner 156 (K!, 4 sheets); On Road Bulwer to Drakensberg Garden, ♂ fl. 22 Feb 1958, Wilson & Buchner 159 (K!, 3 sheets); Drakensberg, upper Umkomaas, ♂ fl. 15 Dec 1958, Werdermann & Oberdieck 1395 (B, K!); Underberg District, Cobham State Forest, Emerald Vale, ♀ fl. & immature fr. 4 Mar 1985, Hilliard & Burtt 18309 (E, NU [NU282256 digital image!]); Underberg District, Cobham State Forest, Emerald Vale, ♂ fl. 14 Jan 1985, Hilliard & Burtt 18061 (E, NU [NU282257 digital image!], PRE); Underberg District, Sunset, Upper Lurane, ♀ fl. & immature fr. 12 Jan 1980, Rennie 1095 (NU [NU0028389 digital image!]); Underberg District, Sunset, Upper Lurane Valley, ♂ fl. 12 Jan 1980, Rennie 1094 (NU [NU0028392 digital image!]); Mpendhle District, Loteni Nature Reserve, Ngondwini valley, ♂ fl.25 Dec 1978, Hilliard & Burtt 11828 (K!, NU [NU0028386 digital image!]); Impendhle District, cultivated in Pretoria, sterile Feb 1962, Roux s.n. (K!, PRE); Bergville District, Cathedral Peak area, ♂ fl. 3 Dec 1952, Killick 1812 (K!, NU [NU0028399 digital image!], PRE); Lions River District, Nhluzane, ♂ fl. 28 Oct 1976, Hilliard & Burtt 9091 (K!, NU [NU0028388 digital image!]); Lions River District, Ross, Umgeni Poort, ♂ fl. 21 Dec 1964, Moll 1400 (K!, (NU [NU0028396 digital image!], PRE); Ngotshe, collected at Ngome Forest and cultivated at Irene, ♀ fl. & immature fr. 20 Dec 1954, Pole Evans 4852 (K!, PRE); Ngotshe District, Ngome, above forest ♀ fr. 2 Apr 1977, Hilliard & Burtt 9932 (K!, NU [NU0028387 digital image!]); Louwsburg District, Ngome, ♂ fl. 14 Dec 1969, Strey 9370 (K!, NU [NU0028397 digital image!]); Vryheid District, Nhlugatshe Mt., ♂ fl. 18 Dec 1965, Hilliard & Burtt 3354 (E, NU [NU0028258 digital image!]); Drakensberg, Estcourt, Cathkin Park, ♂ fl. 22 Jan 1932, Galpin 11744 (K!, PRE); Inanda, no further data, ♂ fl. Without date, received Apr 1881, Wood 1167 (K!); Champagne Castle, ♂ fl. Jan 1955 Odhner 44 (NU [NU0028398 digital image!]); Drakensburg, Giant’s Castle, ♂ fl. 12 Jan 1949, Brunjis-Haylett 20 (NU [NU0028400 digital image!]); Giant’s Castle Game Reserve, ♂ fl. 20 Dec 1987, Cunningham 2720 (NU [NU0028345 digital image!]).
Thanks are due to Benny Bytebier, Snowy Baijnath and Ashley Nicholas, Martin Nickol, John Parnell, Yashica Singh, Terry Trinder-Smith, Braam van Wyk, John Wood and curators of other herbaria listed for help with access to specimens and images. Living plant images were obtained from Neil Crouch, Johan Hurter and the late Tony Abbott. Fieldwork help from John and Sandie Burrows, the late Tony Abbott and Graham Grieve was very important in facilitating this research. Particular thanks to Lucy Smith for the fantastic line drawings in Figs