Solanum incanum [L. ]

Solanum incanum

Citation author:

Citation:

Sp. Pl. 188. 1753.

Type:

Cutivated in Uppsala, Sweden, Herb. J. Burser Vol. 9, no. 20 (neotype, designated by Hepper & Jaeger 1985: UPS!).

Last edited by:

Sandra Knapp (May 2014)

Written by:

Maria S. Vorontsova & Sandra Knapp

Habit:

Erect herb to shrub, 0.4-1.5 m, prickly. Young stems terete, densely stellate-pubescent and prickly, with multangulate, variously stalked trichomes, the stalks to 1 mm long, the rays 6-20, 0.1-0.4 mm long, the midpoints ca. same length as the rays, the prickles 3-9 mm long, 1.5-6 mm wide at base, curved to straight, conical to flattened, pale yellow, stellate-pubescent for at least the lower 1/3, spaced 3-50 mm apart; bark of older stems glabrescent to densely stellate-pubescent, orange-brown to gray.

Sympodial structure:

Sympodial units plurifoliate.

Leaves:

Leaves simple, the blades 6-22 cm long, 4-15 cm wide, ca. 1.5 times longer than wide, ovate, chartaceous, drying concolorous to weakly discolorous, yellowish, densely stellate-pubescent on both surfaces, with porrect, stalked trichomes, the stalks to 0.2 mm long, the rays 8-12, 0.15-0.5 mm long, the midpoints ca. same length as the rays or elongated to 0.6 mm, with 0-5 prickles on both surfaces; the primary veins ca. 5 pairs, the tertiary venation clearly visible abaxially and not visible adaxially; base rounded to cordate; margins almost entire or more often lobed, the lobes (3-)4(-5) on each side, 0.5-2 cm long, extending to 1/4 of the distance to the midvein, broad-deltate, apically rounded; apex rounded to acute; petiole 1-9 cm long, 1/4-1/3 of the leaf blade length, densely stellate-pubescent, with 0-4 prickles.

Inflorescences:

Inflorescences apparently terminal or lateral, 3-8 cm long, not branched, with 5-10 flowers, 1-3 flowers open at any one time, densely stellate-pubescent, unarmed; peduncle 1-4 mm long; pedicels 0.8-1.5 cm long in long-styled flowers, 0.5-0.9 cm long in short-styled flowers, erect to pendent, articulated at the base, densely stellate-pubescent, with 0-30 prickles on long-styled flowers, 0-5 prickles on short-styled flowers; pedicel scars spaced 2-5 mm apart.

Flowers:

Flowers 5-merous, heterostylous and the plants andromonoecious, with the lowermost flower long-styled and hermaphrodite, the distal flowers short-styled and staminate. Calyx 6-10 mm long in long-styled flowers, 4.5-8 mm long in short-styled flowers, densely stellate-pubescent, with 15-60 prickles in long-styled flowers and 0-10 prickles in short-styled flowers, the lobes 2.5-5 mm long in long-styled flowers, 1.5-3 mm long in short-styled flowers, deltate to narrow-deltate, apically acute to obtuse. Corolla 2.4-3 cm in diameter in long-styled flowers, 1.5-2.3 cm in diameter in short-styled flowers, mauve, stellate, lobed for 1/3-1/2 of the way to the base, the lobes 7-10 mm long, 7-10 mm wide in long-styled flowers, 6-9 mm long and 5-7 mm wide in short-styled flowers, broad-deltate, spreading, sparsely stellate-pubescent abaxially, the trichomes porrect, sessile or stalked, the stalks to 0.1 mm, the rays 8-12, 0.1-0.3 mm long, the midpoints ca. same length as the rays. Stamens equal, with the filament tube ca. 2 mm long, the free portion of the filaments ca. 1 mm long; anthers 6-7.5 mm long in long-styled flowers, 4.2-7 mm long in short-styled flowers, connivent, tapering, poricidal at the tips. Ovary stellate-pubescent in the upper 1/4; style 1-1.3 cm long in long-styled flowers, stout, straight or gently curved, moderately stellate-pubescent in the lower 3/4.

Fruits:

Fruit a spherical berry, 1(-2) per infructescence, 2.5-3.5 cm in diameter, the pericarp smooth, dark green with pale green and cream markings when young, yellow at maturity, glabrous; fruiting pedicels 1.3-1.8 cm long, 1.5-2.5 mm in diameter at base, woody, pendulous, with 0-30 prickles; fruiting calyx lobes not elongating, ca. 1/6 the length of the mature fruit, reflexed, with 5-60 prickles.

Seeds:

Seeds ca. 100-200 per berry, 2.2-2.8 mm long, 1.8-2.3 mm wide, flattened-reniform, dull yellow to orange-brown.

Chromosome number:

n=12 (J. Prohens, pers. comm.)

Distribution:

Sub-Saharan Africa north of the equator, from Senegal, Mali, and Niger, to Ethiopia, Somalia, Sudan, and northern Kenya west to Burkina Faso and northern Nigeria; reported from Chad by Brundu & Camarda (2013); also common across the Middle East to western Pakistan; growing in thickets, scrubland, and savanna; 0-1900 m.

Phenology:

Flowering and fruiting throughout the year.

Phylogeny:

Solanum incanum is a member of the Old World clade of subgenus Leptostemonum (the spiny solanums; Levin et al. 2006); within that it belongs to the Eggplant Clade (Vorontsova eta al. 2013) and is one of the very close relatives of the cultivated eggplant (Weese & Bohs 2010; Knapp et al. 2013).

Commentary:

Solanum incanum is distinguished by its lobed leaves with a yellowish color when dry (herbarium sheets), and abundant long-stalked indumentum. In Africa it mostly occurs to the north of the Kenya-Sudan border. Prickles are predominantly gently curved in African populations, but collections with long straight prickles have been made in Arabia. Herbarium specimens of S. incanum bear striking resemblance to the similarly yellowish and densely tomentose southern African S. lichtensteinii; the two species are not sympatric and geographical location data can greatly simplify the identification process. Lester (fide Daunay et al. 2001) cites a difference in fruit diameter (1.6-2.1 cm diameter in S. incanum versus 3.5-4.5 cm diameter in S. lichtensteinii), but measurements from herbarium specimens suggest the ranges overlap, with fruits 2.5-3.5 cm diameter in S. incanum and 2.5-4.5 cm diameter in S. lichtensteinii.

Solanum incanum is probably the closest African relative of the cultivated aubergine S. melongena (Weese & Bohs 2010), and forms part of a polytomy with S. insanum and S. melongena in an analysis with multiple accessions (Vorontsova et al. 2013); different markers will be needed to unravel the complex relationships in these close relatives of the cultivated eggplant.

The name “Solanum incanum” has been commonly and incorrectly applied to S. campylacanthum and numerous other species of prickly African solanums and care must be taken with the application of this name. Samuels (2013) incorrectly cited the neotype as occurring at LINN; the Burser herbarium is held at UPS.

In describing S. sanctum, Linneaus cited his own earlier species S. incanum in synonymy, making the former illegitimate. Dunal (1852: 369) cited S. sanctum in synonymy in his description of S. hierochuntinum, making this name also illegitimate; he stated he was changing the epithet to avoid confusion (“Nomen sanctum mutavi, quia pluribus speciebus confusis datum…”).

References:

Brundu, G., Camarda, I. 2013. The Flora of Chad: a checklist and brief analysis. PhytoKeys 23: 1-18. doi: 10.3897/phytokeys.23.4752

Daunay, M-C., R. N. Lester, and G. Ano. 2001. Eggplant. In Tropical plant breeding, ed. A. Charrier, M. Jacquot, S. Hamon, and D. Nicolas, 199-222. Enfield, Plymouth: Science Publishers Inc.

Dunal, M.-F. 1852. Solanaceae. In Prodromus Systematis Naturalis Regni Vegetabilis vol. 13(1), ed. A. P. De Candolle, 1-690. Paris: Victor Masson.

Knapp, S., M. S. Vorontsova, and J. Prohens. 2013. Wild relatives of the eggplant (Solanum melongena L.: Solanaceae): new understanding of species names in a complex group. PLoS ONE 8(2): e57039. doi:10.1371/journal.pone.0057039.

Levin, R. A., N. R. Myers, and L. Bohs. 2006. Phylogenetic relationships among the “spiny solanums” (Solanum subgenus Leptostemonum, Solanaceae). Amer. J. Bot. 93: 157-169.

Samuels, J. 2013. An updated look at the taxonomy of the brinjal eggplant complex. In Proceedings of the XV EUCARPIA meeting on genetics and breeding of capsicum and eggplant, ed. S. Lanteri and G. L. Rotino, 253-261. Turin: Università degli Studi di Torino.

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. Somalia: Moh (Darod language, Gillett 4127), Makarube (Maunder 69), Ducuur (Kuchar 17155). Ethiopia: Embaye (Amharic language, Archer 9623).

Uses. Medicinal, and used to tan leather.

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Solanum incanum L.

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Solanum incanum L.

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