Pseudovigna sulaensis R.Clark & Burgt

Clark, R., van der Burgt, X., Banks, H. et al. Kew Bull (2011) 66: 589. https://doi.org/10.1007/s12225-011-9314-8

Morphology General Habit

Herb, stems annual, twining, not climbing, to several metres long, branched; sprouting from perennial woody rootstock of c. 3.5 cm thick with several side roots to 2 cm thick

Morphology General Indumentum

Indumentum of erect, long, white to pale brown trichomes present on most parts of the plant (henceforth to be referred to simply as ‘trichomes’)

Morphology Stem

Stems longitudinally ridged, moderately to densely covered with trichomes Internodes 7 – 16.5 cm

Morphology Leaves Stipules

Stipules persistent, ovate, acute, striate, 3.5 – 8 × 3 – 6 mm, outer surface moderately covered with trichomes, inner surface glabrous

Morphology Leaves Stipel

Stipels persistent, filiform, striate, 3 – 4 × 0.5 mm, outer surface moderately covered with trichomes, inner surface glabrous

Morphology Leaves

Leaflets mid-green above, paler, greyish green below; terminal leaflet ovate to rhomboid, lateral leaflets elliptic to ovate to rhomboid, asymmetric; terminal leaflet 4 – 10 × 3 – 9 cm, laterals 3 – 9 × 2.5 – 7 cm; all leaflets 3 – 5-veined from the base, secondary veins reticulate, veins raised on both surfaces, more prominent below; upper surface sparsely covered with trichomes, lower surface moderately covered with trichomes; when young very densely covered with cream coloured trichomes along primary and secondary veins and pale green trichomes on the lamina Leaves pinnately 3-foliolate, petioles 2 – 12 cm, rhachis 1 – 4 cm, both longitudinally ridged, petiolules 1 – 4 mm, all moderately to densely covered with trichomes

Morphology Reproductive morphology Inflorescences

Inflorescences axillary pseudoracemes, 5 – 38 cm long including the peduncle of 2.5 – 27.5 cm, fertile part 2 – 8 cm, upper part erect; 12 – 30 flowers, densely congested, in pairs or threes on fleshy nodes (the nodes often with several projections where a flower has failed to develop, or has fallen off), axis sparsely to moderately covered with trichomes, pedicels c. 1 mm

Morphology Reproductive morphology Inflorescences Bracts

Bracts persistent, inserted in pairs at the base of the pedicel, lanceolate, inrolled, striate, 3 – 4 × 1 mm, outer surface densely covered with trichomes, inner surface glabrous

Morphology Reproductive morphology Inflorescences Bracteoles

Bracteoles persistent, inserted in pairs at the base of the calyx, 2 – 3 × 0.5 mm, lanceolate, not striate, outer surface sparsely covered with trichomes, inner surface glabrous

Morphology Reproductive morphology Flowers

Flowers violet; standard petal light violet with darker violet centre and darker violet veins; wing and keel petals violet, all petals glabrous; calyx dark green to blackish, tube 3 – 4 mm deep, lobes narrowly triangular, 3 – 4 mm long, the upper 2 lobes fused along c. ⅔ of their length; outer surface moderately covered with trichomes, inner surface of lobes moderately covered with short, fine, translucent white trichomes, inner surface of tube glabrous

Morphology Reproductive morphology Flowers Corolla

Keel petals fused along part of their length, blade 8 – 10 × 3 – 4 mm, claw 4 – 5 mm, blade with slight pocket (larger than on wing) Standard petal obovate, blade c. 12 × 9 mm, claw 1.5 – 2 mm, apex of claw slightly inrolled

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens diadelphous, 9 + 1, filaments 12 – 13 mm, glabrous, anthers c. 0.5 mm long; ovary with 7 ovules, c. 5 mm long, densely hairy, style flattened in basal half, apical half cylindrical, style c. 8 mm long; stigma capitate, penicillate

Morphology Reproductive morphology Fruits Infructescences

Infructescence fertile part to 12 cm long

Morphology Reproductive morphology Fruits

Fruit 3 – 4 × 0.4 cm, not constricted between the seeds, moderately to densely covered with short and long, white to brown trichomes

Morphology Reproductive morphology Seeds

Seeds 5 – 7 per fruit; c. 4 × 2.5 × 2 mm, dull black, oblong-cylindrical, surface reticulate (foveolate)

Seedling

Seedlings with first leaf unifoliolate, leaflet c. 1 cm diam., petiole 3 mm; consecutive leaves gradually becoming larger, unifoliolate up to at least the 5th leaflet, to 5  ×  4.4 cm, petiole to 3 cm.

Distribution

Africa: Sierra Leone, Tonkolili Distr. and Koinadugu Distr., Sula Mts. The new species has been found on 10 hill summits in the Sula Mts.

Ecology

Grassland and wooded grassland on rocky soils, usually on or near summits of hills; alt. 570 – 950 m. Rainfall c. 2500 – 3000 mm/year.

Conservation

Pseudovigna sulaensis has been found at 10 localities, which are all situated in the Sula Mts. Of these 10 localities, nine are on summits of hills, including the highest summit of the Sula Mts at 950 m altitude. When standing on the summits of these hills, at least 10 other hills can be seen with P. sulaensis habitat at their summits. It is therefore very likely that P. sulaensis occurs in 20 or more sites in the Sula Mts. The P. sulaensis populations on some of these sites are threatened. A mining company is planning to mine iron ore in the Sula Mts. Two of the 10 sites are planned to be mined in the near future. One of the sites in the northern Sula Mts is used for cattle grazing, which damages the above-ground parts of the plants due to trampling, although the cattle have not been observed to eat the plants. Of the 10 known sites, seven are at present safe, without any human influence visible and no mining planned in the near future. The extent of occurrence of the species is c. 350 km2. In view of this, the conservation status of P. sulaensis is here assessed as Vulnerable VU B1ab(iii) (IUCN 2001). However, should more hills with P. sulaensis be used for iron ore extraction, the conservation status of the species may change to Endangered. The mining company that is planning the mining activities is assisting with measures to protect the species, such as seed banking and transplanting threatened populations by seed. The species should also be searched for on other hill summits in the Sula Mts and beyond.