Solanum polhillii
Citation:
Syst. Bot. 35: 902. 2010.
Type:
KENYA. Masai: Narok District, Ewaso Ngiro-Loliondo Road where it crosses the Masan River, 13 Dec 1963, B. Verdcourt 3838 (holotype: EA! [no barcode]; isotypes: BR! [no barcode], K! [K000441234, K000441243]).
Last edited by:
Sandra Knapp (May 2014)
Written by:
Maria S. Vorontsova & Sandra Knapp
Habit:
Erect herb or shrub, 1-2 m, prickly or unarmed. Young stems terete, sparsely to densely stellate-pubescent and prickly or unarmed, with porrect, variously stalked trichomes, the stalks to 0.2 mm long, the rays 7-9, 0.1-0.2 mm long, the midpoints same length as the rays or shorter, often reduced to globular glands, the prickles 2-3(-6) mm long, 0.5-1.5 mm wide at base, straight, occasionally curved, perpendicular to the stem, orange-brown to yellow, glabrous or with occasional trichomes, spaced 3-10 mm apart; bark of older stems glabrescent, gray or brown.
Sympodial structure:
Sympodial units difoliate, not geminate.
Leaves:
Leaves simple, the blades 2-6 cm long, 1-4 cm wide, 1.5-2 times longer than wide, ovate, chartaceous, drying discolorous, yellow-green, densely stellate-pubescent on both surfaces, with porrect, stalked trichomes, the stalks to 0.2 mm long, the rays ca. 8, 0.1-0.3 mm long, the midpoints same length as the rays or shorter, unarmed on both surfaces; the primary veins 3-4 pairs, the tertiary venation usually not visible to the naked eye; base cordate, sometimes rounded to cuneate; margins entire to weakly lobed, the lobes 1-2 on each side, 0-0.3 cm long, extending to 1/4 of the distance to the midvein, broad-deltate, apically rounded; apex rounded or obtuse; petiole 0.3-2.5 cm long, 1/3-2/3 of the leaf blade length, moderately stellate-pubescent, with 0(-2) prickles.
Inflorescences:
Inflorescences apparently terminal or lateral, 2-4.5 cm long, unbranched, with 2-6 flowers, 1-3 flowers open at any one time, moderately stellate-pubescent, with 0-3 prickles; peduncle 0-5 mm long; pedicels 1-1.5 cm long, erect, inflated in the upper half, articulated at the base, moderately stellate-pubescent, with 0-5 prickles; pedicel scars spaced 1-6 mm apart.
Flowers:
Flowers 5-merous, heterostylous and the plants andromonoecious, with the lowermost 1-3 flowers long-styled and hermaphrodite, the distal flowers short-styled and staminate. Calyx 8-16 mm long, densely stellate-pubescent, with 0(-10) prickles, the lobes 4.5-12 mm long, narrow-deltate to narrow-oblong, apically long-acuminate. Corolla 2-4.2 cm in diameter, mauve to purple, stellate, lobed for 2/3-3/4 of the way to the base, the lobes 7-15 mm long, 4.5-10 mm wide, ovate, spreading, densely stellate-pubescent abaxially, the trichomes porrect, subsessile, the stalks to 0.1 mm, the rays ca. 8, 0.1-0.25 mm long, the midpoints same length as the rays or shorter. Stamens equal, with the filament tube 2-2.5 mm long, the free portion of the filaments 1.7-2 mm long; anthers 4.5-8 mm long, connivent, tapering, poricidal at the tips. Ovary densely stellate-pubescent over its entire surface; style 0.8-1.2 cm long in long-styled flowers, slender, curved, stellate-pubescent in the lower 1/4.
Fruits:
Fruit a spherical berry, 1(-2) per infructescence, 1.3-2 cm in diameter, the pericarp smooth, dark green with pale green and cream markings when young, yellow to orange at maturity, glabrous; fruiting pedicels 0.8-4 cm long, 0.6-1 mm in diameter at base, herbaceous, becoming woody, the apical 5-10 mm inflated, pendulous, with 0-15 prickles; fruiting calyx lobes not elongating, ca. 1/3 the length of the mature fruit, with 0(-10) prickles.
Seeds:
Seeds ca. 30-100 per berry, 2.8-3 mm long, 2-2.5 mm wide, flattened-reniform, pale yellow to orange-brown.
Chromosome number:
Not known
Distribution:
Kenya and Tanzania; savanna, rocky hillsides, bushland and scrub, on granite, volcanic rocks or red sandy soil; 1800-2200 m.
Phenology:
Flowering and fruiting throughout the year.
Phylogeny:
Solanum polhillii is a member of the large unresolved Anguivi Grade of the Old World clade of subgenus Leptostemonum (Vorontsova et al. 2013); it may be related to the Asian species Solanum violaceum.
References:
Bitter, G. 1923. Solana Africana. IV. Repert. Spec. Nov. Regni Veg., Beih.. 16: 1-320.
Vorontsova, M. S., S. Stern, L. Bohs, and S. Knapp. 2013. African spiny Solanum (subgenus Leptostemonum, Solanaceae): a thorny phylogenetic tangle. Bot. J. Linn. Soc. 173: 176-193. doi:10.1111/boj.12053
Common names and uses:
Local Names. Kenya: Endulelei, Oliasuria, Entenelua-Narok (Masai langugae).
Uses. Medicinal.
Solanum polhillii is an attractive erect pubescent shrub with conspicuous mauve flowers, broad pubescent leaves and apically inflated pedicels. Leaf size, petiole length and prickliness vary widely with aridity, nutrient availability, and herbivory; particularly remarkable is the variation in flower size, with the corolla reaching 2-4.2 cm wide and the anthers 4.5-8 mm long. The size of the flowers and fruits is intermediate between andromonoecious large-fruited and non-andromonoecious small-fruited species, supporting the non-monophyly of Bitter's original sections based on fruit size and sex expression (Bitter 1923).