Solanum ruvu
Citation:
J. E. Afr. Nat. Hist. 99: 230. 2011 [”2010”].
Type:
TANZANIA. Morogoro, Ruvu Forest Reserve, 200 m, 17 Jul 2000, B. Mhoro UMBCP 113 (holotype: K! [K000441557]; isotype, MO).
Last edited by:
Sandra Knapp (May 2014)
Written by:
Maria S. Vorontsova & Sandra Knapp
Habit:
Scrambling shrub, ca. 1 m, prickly. Young stems terete, almost glabrous and prickly, with porrect, sessile trichomes present on the youngest parts only, the rays 2-4, ca. 0.05 mm long, the midpoints ca. same length as the rays, with minute simple hairs, the prickles 4-6 mm long, ca. 0.2 mm wide at base, straight, perpendicular to the stem, straw yellow to brown, glabrous, spaced 1-7 mm apart; bark of older stems glabrous, green-brown.
Sympodial structure:
Sympodial units difoliate, not geminate.
Leaves:
Leaves simple, the blades 9-12 cm long, 2.5-4.5 cm wide, 2.5-4 times longer than wide, elliptic, membranous, drying concolorous, brown-green, almost glabrous on both surfaces, with porrect, sessile trichomes, the rays 2-4, ca. 0.05 mm long, the midpoints ca. same length as the rays, with minute simple hairs, with numerous prominent prickles on primary and secondary veins on both sides of the leaf, the prickles 4-8 mm long, straight on both surfaces; the primary veins 6-8 pairs, the tertiary venation visible on both surfaces; base cuneate; margins subentire; apex long-acuminate; petiole 0.5-1.5 cm long, 1/5-1/10 of the leaf blade length, glabrous, usually with several prickles.
Inflorescences:
Inflorescences apparently lateral, 5-9 cm long, not branched, with 10-15 flowers, 1-2 flowers open at any one time, glabrous, densely armed, the prickles like those on the stems evenly distributed down the whole length of the inflorescence; peduncle 10-15 mm long; pedicels 0.7-1.2 cm long, erect, articulated at the base, glabrous, unarmed; pedicel scars spaced 1-10 mm apart.
Flowers:
Flowers 5-merous, apparently all perfect. Calyx 2.5-5 mm long, glabrescent, with numerous prickles, the lobes 1.5-3.5 mm long, deltate, apically long-acuminate. Corolla 1.2-1.8 cm in diameter, fresh color not known, stellate, lobed for ca. 4/5 of the way to the base, the lobes 6-8 mm long, 1.5-2 mm wide, narrow-deltate, spreading, sparsely stellate-pubescent abaxially, the stellate trichomes porrect, sessile, the rays 2-4, very short, less than 0.5 mm long, the midpoints ca. same length as the rays. Stamens equal, with the filament tube ca. 1 mm long, the free portion of the filaments ca. 0.8 mm long; anthers 5-6 mm long, connivent, tapering, poricidal at the tips. Ovary with minute glandular hairs towards the apex; style ca. 0.8 cm long, slender, gently curved, glabrous.
Fruits:
Fruit not known.
Seeds:
Seeds not known.
Chromosome number:
Not known.
Distribution:
Known only from the type locality in Tanzania; growing in wet coastal forest understory; ca. 200 m elevation.
Phenology:
The only known collection was flowering in July.
Phylogeny:
Solanum ruvu is, on morphological and distribution grounds, a member of the Old World clade of subgenus Leptostemonum (The spiny solanums; Levin et al. 2006). Based on its morphology it could be a member of the Climbing Clade (Vorontsova et al. 2013), along with Solanum zanzibarense with which it is similar (see commentary).
References:
Vorontsova, M. S., and F. M. Mbago. 2011 [2010]. New Solanum from Tanzanian coastal forest may already be extinct. J. E. Afr. Nat. Hist. 99: 227-234.
Conservation status:
Possibly extinct (EX); known only from the type collection and not found in intensive searches (see Vorontsova & Mbago 2011).
The long filiform inflorescences with a dense covering of long straight prickles on the rachis of S. ruvu have no parallels among the known Solanum species in Africa and Madagascar. The affinities of S. ruvu are most likely with S. zanzibarense, the only other scandent and sometimes subglabrous eastern African coastal forest species with subentire leaves, thin stems, and prickles that are sometimes straight. A similarly dense covering of long and flexible prickles/bristles is found on two other eastern African species that are not directly related to S. ruvu such as the savanna species S. setaceum in the Anguivi grade and the woody S. schumannianum in the Giganteum clade.
Failure to recollect this species on recent searches in the area of the type collection and adjacent habitat suggests it may be extinct (see Vorontsova & Mbago 2011).