Solanum forskalii Dunal, Hist. Nat. Solanum 237. 1813.

Aubriot, Xavier & Knapp, Sandra, 2022, A revision of the " spiny solanums " of Tropical Asia (Solanum, the Leptostemonum Clade, Solanaceae), PhytoKeys 198, pp. 1-270 : 1

14. Solanum forskalii Dunal, Hist. Nat. Solanum 237. 1813.

Fig. 23

Solanum villosum Forssk., Fl. Aegypt.-Arab. 47. 1775, nom. illeg. non Solanum villosum Mill. Type. Yemen. Wadi Surdud, Feb 1763, Herb. P. Forsskål 414 (holotype: C [C10003107]).

Solanum macilentum A.Rich., Tent. Fl. Abyss. 2: 105. 1850. Type. Ethiopia. Choho, R. Quartin-Dillon & A. Petit s.n. (lectotype, designated by Lester 1997, pg. 286: P [P000343696]; isolectotypes: P [P0003436967, P000343698]).

Solanum albicaule Kotschy ex Dunal, Prodr. [A. P. de Candolle] 13(1): 204. 1852. Type. Sudan. Kordofan: Nubia, Cordofan Chursi, 29 Dec 1839, C. Kotschy 309 (lectotype, designated by Lester 1997, pg. 287: G-DC [G00145871]; isolectotypes: B, BM [BM000778322], E [E00193284], ER, GOET, K [K000414013, K000414014, K000414015], LZ, M [M0105605, M0105606], MO [acc. # 3942648], MPU, NY, P [P00344693, P00344694, P00344695], STU [STU000027], TCD [TCD0000843], W [acc. # 1889-0293762, acc. # 0000634], WAG [WAG0003359]).

Solanum heudelotii Dunal, Prodr. [A. P. de Candolle] 13(1): 205. 1852. Type. Senegal. near Gabor, 1839, J. Heudelot 417 (45) (lectotype, designated by Lester 1997, pg. 287: P [P00344004]; isolectotypes: K [K000414051], MPU, P [P00344005, P00344006], UPS).

Solanum hadaq Deflers, Bull. Soc. Bot. France 43: 122. 1896. Type. Yemen. Schoukra, Bilad Fodhli, J. Areys, 30 k a’ l E.N.E. de Schughra, 150 m, 22 Mar 1890, M. Deflers 377 (lectotype, designated by Vorontsova and Knapp 2016, pg. 159: P [P00051780]; isolectotypes: K [K000441183], P [P00051781, P00051782).

Solanum scindicum Prain, J. Asiat. Soc. Bengal, Pt. 2, Nat. Hist. 65: 542. 1896. Type. Pakistan. Sind: Scinde, T. Cooke s.n. (lectotype, designated by Vorontsova and Knapp 2016, pg. 159: CAL [CAL0000018701]; isolectotype: K [K000441223]).

Solanum albicaule Kotschy ex Dunal var. parvifrons Bitter, Repert. Spec. Nov. Regni Veg. Beih. 16: 102. 1923. Type. South Sudan. “Nördliches Darfur, El Fascher", J.D.C. Pfund 407 (syntypes: B, destroyed, Z, not found; no additional duplicates found).

Type.

Based on (replacement name for) Solanum villosum Forssk.

Description.

Erect or scandent shrub, 0.5-1 m, prickly. Young stems slender, ascendent to erect, densely stellate-pubescent and prickly, the pubescence of porrect, sessile or occasionally stalked trichomes, the stalks to 0.15 mm long, the rays 6-10, 0.15-0.3(-0.5) mm long, the midpoints same length as the rays or up to 1.5 mm, occasionally rounded, the prickles 3-10 mm long, 1-3 mm wide at the base, straight, occasionally curved, flattened, strongly reflexed, pale yellow to brown, spaced 1-10 mm apart; bark of older stems densely stellate-pubescent, sometimes glabrescent, brown to grey or orange-grey. Sympodial units difoliate, not geminate. Leaves simple, entire to weakly lobed, the blades 1-4(-6) cm long, 0.5-3(-4) cm wide, 1-2 times longer than wide, ovate, membranous to chartaceous, drying concolorous to discolorous, yellow-green to grey-green or brown-green, glabrescent to moderately stellate-pubescent on both surfaces, with porrect, sessile, sometimes stalked trichomes, the stalks to 0.2 mm long, the rays 6-10, 0.2-0.4(-1) mm long, the midpoints ca. same length as the rays, sometimes to 1.5 mm long, with 0(-3) prickles on both surfaces; the primary veins 2-3 pairs, the tertiary venation not visible to the naked eye; base cordate to rounded, the lobes 2(-3) on each side, 0.2-0.4 cm long, extending to 1/4 of the distance to the midvein, broadly deltate, apically rounded to obtuse; apex rounded to obtuse; petiole 0.2-1.6(-2.5) cm long, 1/4-2/3 of the leaf blade length, densely stellate-pubescent, with 0(-5) prickles. Buds ellipsoid, the corolla strongly exserted from the calyx before anthesis. Inflorescences apparently terminal or lateral, 2-6.5 cm long, unbranched or forked, with (1-)2-20 flowers, 1-10 flowers open at any one time, densely stellate-pubescent, with 0(-5) prickles; peduncle 0.1-0.4(-1.5) cm long; pedicels 0.2-1 cm long, erect, articulated at the base, densely stellate-pubescent, with 0(-6) prickles; pedicel scars spaced 0.5-1.5 mm apart. Flowers 5-merous, apparently all perfect. Calyx 2-4.5 mm long, the lobes 0.5-2 mm long, ca. 1 mm wide, deltate, apically acuminate, moderately stellate-pubescent, with 0(-5) prickles. Corolla 1.3-2.4 cm in diameter, mauve to purple, stellate, lobed ca. 4/5 of its length, the lobes 6-11 mm long, 1.5-2 mm wide, deltate, reflexed or spreading, stellate-pubescent abaxially, the trichomes porrect, sessile or stalked, the stalks to 0.15 mm, the rays 4-10, 0.1-0.2 mm long, the midpoints shorter than the rays or to 0.5 mm long. Stamens equal; filament tube ca. 0.1 mm long; free portion of the filaments 0.7-1 mm long; anthers 4.5-7 mm long, connivent to spreading, tapering, yellow, poricidal at the tips, the pores directed distally. Ovary glabrous; style 0.9-1.2 cm long, slender, curved at the apex, glabrous. Fruit a globose berry, 1-10 per infructescence, 0.6-0.9 cm in diameter, the pericarp smooth, orange to red at maturity; fruiting pedicels 0.7-1.6 cm long, 0.3-0.4 mm in diameter at the base, 2-2.5 mm in diameter at the apex, spreading to somewhat deflexed from the weight of the fruit, with 0(-10) prickles; fruiting calyx not accrescent, covering 1/4(-1/2) of the mature fruit, with 0(-5) prickles. Seeds ca. 5-15 per berry, 2.5-4 mm long, 1.8-3 mm wide, flattened-reniform, almost black, the testal cells somewhat sinuate in outline. Chromosome number: n = 12 ( Khatoon and Ali 1993), 2n = 24 ( Al Wadi 2002).

Distribution

(Fig. 24 ). Solanum forskalii is found from northeastern Africa and Arabian Peninsula to Pakistan and western India (Rajasthan and Gujarat).

Ecology and habitat.

Solanum forskalii is a desert plant growing on stony ground and rocky slopes, often on granite, elevation not recorded on herbarium sheets we have seen from India (from sea level to 2,000 m elevation fide Vorontsova and Knapp 2016)

Common names and uses.

India. Rajasthan: nar-kanta [Hindi] ( Singh 1991, as S. albicaule ).

Conservation status

( Knapp 2021b). Solanum forskalii has been formally assessed as least concern (LC; https://www.iucnredlist.org/species/101526207/101526210).

Discussion.

Although Vorontsova and Knapp (2016) suggested collections of S. forskalii from India might be accidental introductions, it is reported as fairly common in the Indian state of Rajasthan ( Singh 1991). It is easily recognised by its white-coloured stems, resulting from the dense pubescence of overlapping stellate trichomes with long, delicate rays, and abundant, recurved prickles.

Solanum forskalii can be distinguished from S. cordatum by its porrect trichomes with 6-10 rays over 0.15 mm long on the young stems (versus trichomes with 12-18 rays under 0.15 mm long on the young stems of S. cordatum ), 1-20 flowers per inflorescence (versus 1-2 flowers per inflorescence in S. cordatum ), and anthers 4.5-7 mm long (versus anthers 3-5 mm long in S. cordatum ). The trichome rays of S. forskalii are much thinner and more delicate than those of S. cordatum , which appear stout and almost lepidote. There is considerable variability within S. forskalii in Africa with respect to inflorescence length, prickle size and trichome midpoint length ( Vorontsova and Knapp 2016).

Specimens examined.

See Suppl. materials 1-3.

Figures

Figure 23. Solanum forsskalii Dunal. Herbarium specimen collected in India in 1973 (Tiwari 941, CAL 0000031126). Photograph credit: © The Director, Botanical Survey of India, Kolkata.

Figure 24. Distribution of S. forsskalii.