Vigna Savi

Legumes of the World. Edited by G. Lewis, B. Schrire, B. MacKinder & M. Lock. Royal Botanic Gardens, Kew. (2005)

Note

Previous accounts of the Phaseoleae by Baudet (1978) and Lackey (1981) recognised 90 and 84 genera and c. 1540 and 1480 species respectively in the tribe. In an equivalent, i.e. traditionally held view of Phaseoleae, 89 genera and (1554)–1567–(1580) species are treated here (Table 9; Fig. 47). Changes between Baudet (1978) and this treatment are that eleven genera are now in synonymy or have subsequently been placed in Millettieae, two genera have been transferred from Desmodieae and eight new genera have been added. Vigna has traditionally been thought to comprise some 150–200 species, but Vigna sens. strict. may contain fewer than 100.

Recent molecular analyses of the tribe, however, have emphasised both the polyphyletic and paraphyletic nature of Phaseoleae as traditionally circumscribed (Bruneau & Doyle, 1990; Doyle & Doyle, 1993; Delgado Salinas et al., 1993; Bruneau et al., 1995; Doyle et al., 1997, 2000; Kajita et al., 2001; Goel et al., 2001; Lee & Hymowitz, 2001). This has required a radical realignment of elements of the phaseoloids (Table 9; Fig. 47), with at least two major clades being evident: Phaseoleae subtribes Diocleinae and Ophrestiinae which together with tribe Abreae are allied to the core-Millettieae (Fig. 45), and the remaining groups comprising a Phaseoleae sens. lat. clade. The rbcL phylogeny of Kajita et al. (2001) and the ITS analysis of Hu et al. (2002) are equivocal as to which clade subtribe Clitoriinae belongs. Phaseoleae sens. lat. also includes two traditionally independent tribes, the Desmodieae and Psoraleeae. Delimiting a recircumscribed Phaseoleae sens. strict is thus very problematic. A solution may be to recognise a broad tribe Phaseoleae, comprising the subtribes Kennediinae, Cajaninae, Phaseolinae and Glycininae, assorted basally branching genera, and tribes Desmodieae and Psoraleeae (both treated at subtribal level).

The New World species of Vigna may be significantly reduced with the removal of subgenus Sigmoidotropis (c. 17 spp., including V. caracalla (L.) Verdc., illustrated above) which is polyphyletic with respect to the rest of Vigna (Delgado Salinas et al., 1993)

Habit

Herbs

Ecology

Seasonally dry tropical woodland, wooded grassland and grassland, often in well drained sites with low fertility

Distribution

Palaeotropics and subtropics (c. 80-85 spp., mostly in Africa [c. 55-60 spp.; 4 spp. endemic to Madagascar] and SE Asia [c. 21 spp.]), c. 22 spp. in Neotropics and subtropics (but see taxonomic notes)

Leguminosae, B. Mackinder, R. Pasquet, R. Polhill & B. Verdcourt. Flora Zambesiaca 3:5. 2001

Habit

Climbing, twining, prostrate or erect herbs or subshrubs, rarely small shrubs, mostly from woody or tuberous rootstocks, without hooked hairs (as in Phaseolus).

Leaves

Leaves pinnately, more rarely subdigitately, 3-foliolate, 1-foliolate or simple; leaflets entire, venation usually reticulate, rarely with secondary nerves parallel (V. multinervis) or tertiary nerves parallel; stipules usually bilobed or spurred at the base, sometimes peltate, rarely truncate; stipels persistent, rarely absent.

Inflorescences

Inflorescence axillary, falsely racemose or flowers in dense 1–many-flowered subumbellate clusters or fasciculate; rhachis thickened and glandular at the point of insertion of the pedicels, flowers paired at each node; bracts and bracteoles deciduous, usually similar in shape and nervation; pedicel shorter than or as long as the calyx, extending or not as the pod matures.

Calyx

Calyx 5-lobed, 2-lipped; lower lip 3-lobed, the middle lobe usually the longest; upper lip of 2 lobes completely or partly united.

Corolla

Corolla small or medium-sized, yellow, blue or purple inside (internal face of standard, external face of wings), greenish outside (external face of standard), all petals of subequal length; standard glabrous (except in V. heterophylla), emarginate, usually slightly wider than long and symmetrical, with inflexed auricles and appendages on the internal face, less often without appendages; appendages of the standard are based on a U-shaped pattern with one on each half of the standard, but the pattern is rarely complete; it can be reduced to the central part of the U with the appendages appearing parallel and very close together (central position), or sometimes joined and appearing V- or X-shaped (V.luteola or V. monophylla for example); it can be reduced to the lateral part of the U with the appendages appearing parallel but spaced apart (lateral position) (as in V. unguiculata); it can be reduced to the basal part of the U with the appendages appearing perpendicular to the standard axis (V. comosa); keel whitish except for the beak (if there is a beak), usually fused on the upper side, truncate, obtuse or conspicuously beaked, sometimes the beak incurved through up to 180° (V. radiata), sometimes with a distinct conical pocket on the left-hand petal (V. vexillata for example).

Stamens

Vexillary stamen free; 5 shorter filaments (including the vexillary one) sometimes with a pair of joined glands below each anther (in subgenus Haydonia); anthers uniform.

Pollen

Pollen triporate, exine coarsely reticulate (except in subgenus Haydonia).

Pistil

Ovary 1–many-ovuled; style with tenuous lower part obsolete to quite long, filiform or flattened, upper part thickened and cartilaginous, straight or curved, upper portion barbate or hirsute on the internal face, produced beyond the stigma to form a short to long subulate beak (except in subgenus Haydonia); stigma completely lateral or oblique.

Fruits

Pods linear or linear-oblong, usually terete, rarely flattened (V. macrorhyncha), with sutures not raised (except V. macrorhyncha), straight or curved, not septate (seeds are separated by a spongy tissue, not as woody as in Dysolobium and Pachyrhizus); style caducous.

Seeds

Seeds mostly reniform or quadrate, thickness usually slightly less than width, usually cream-coloured, cream-coloured in combination with grey, mottled and speckled patterns, or black; hilum small or elongate; aril obsolete to well developed, usually excentric, often 3-pronged.

Cytology

Chromosome count usually 2n=22, rarely 2n=20.

Leguminosae, J. B. Gillett, R. M. Polhill & B. Verdcourt. Flora of Tropical East Africa. 1971

Habit

Herb with short creeping stems

Leaves

Leaves pinnately 3-foliolate; stipules spurred, striate; stipels small, persistent

Inflorescences

Inflorescences axillary, few-flowered; peduncle bending downwards after flowering so that the fruits develop underground

Flowers

Fertile flowers small, without petals, ± 2 mm. long; functionally male flowers possessing petals

Calyx

Calyx 5-lobed, 2-lipped; lower lip of 3 short lobes; upper pair of lobes joined to form a bifid lip

Corolla

Standard auriculate, with 2 obscure appendages, glabrous

Stamens

Vexillary stamen free; anthers uniform

Ovary

Ovary 1–3-ovuled

Fruits

Pods irregularly oblong-obovoid, beaked with a recurved style-base

Seeds

Seeds ovoid or ellipsoid, slightly keeled; hilum elliptic, placed towards one end; aril almost obsolete, thin, white.