Solanum cordatum Forssk., Fl. Aegypt.-Arab. 47. 1775.

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

9. Solanum cordatum Forssk., Fl. Aegypt.-Arab. 47. 1775.

Fig. 14

Solanum gracilipes Decne., Voy. Inde [Jacquemont] 4(Bot.): 113, t. 119. 1844. Type. India. "India Borealis Occidentalis", V. Jacquemont 63 (holotype: P [P00054212]).

Solanum sabeorum Deflers, Bull. Soc. Bot. France 43: 122. 1896. Type. Yemen. N side of Mount Nakhai, Bilad Fodhli, 800 m, 31 Mar 1890, M. Deflers 488 (lectotype, designated by Vorontsova and Knapp 2016, pg. 127: P [P00051784; isolectotypes: K [K000441136], P [P00051784, P00051785, P00051786]).

Solanum darassumense Dammer, Bot. Jahrb. Syst. 38: 57. 1905. Type. Somalia. Arussi-Galla, Darassuma, 900 m, Apr 1900, H. Ellenbeck 2024 (lectotype, designated by Vorontsova and Knapp 2010, pg. 1596: GOET).

Solanum obbiadense Chiov., Boll. Soc. Bot. Ital. 1925: 106. 1925. Type. Somalia. "Sultanate of Obbia, Biomal", 2 May 1924, N. Puccioni & J. Stefanini 1061 [605] (neotype, designated by Vorontsova and Knapp 2016, pg. 127: FT [FT003066]).

Solanum nummulifolium Chiov., Boll. Soc. Bot. Ital. 1925: 107. 1925. Type. Somalia. "Sultanate of Obbia, Biomal", 2 May 1924, N. Puccioni & J. Stefanini 551 [605] (neotype, designated by Vorontsova and Knapp 2016, pg. 127: FT [FT003065]).

Type.

Yemen. Naquil Khailan between Beui Harath and Nehm, NE of Sana’a, 2400 m, 12 May 1978, J.R.I. Wood 2327 (neotype, designated by Wood 1984, pg. 136: K [K000441137]; isoneotype: BM [BM000942294]) .

Description.

Scandent, sometimes erect herb to shrub, 0.3-1 m, unarmed or prickly. Young stems slender, creeping to ascendent, glabrescent, unarmed or sparsely prickly, the pubescence of multangulate, sessile trichomes visible to the naked eye as white dots, the rays 12-18, up to 0.1(-0.15) mm long, the midpoints reduced to a globular gland, the prickles, if present, 0-4 mm long, 0.1-2(-6) mm wide at the base, straight, sometimes slightly reflexed to curved, perpendicular to the stem, pale yellow to brown; bark of older stems glabrous, dark brown or dark grey to black. Sympodial units difoliate, not geminate. Leaves simple, entire, the blades 0.7-1.5(-3) cm long, 0.7-1.3(-3.5) cm wide, 1(-1.5) times longer than wide, orbicular, sometimes ovate, membranous, drying concolorous, yellowish green, glabrescent on both surfaces, with porrect, sessile, sometimes stalked trichomes, the stalks to 0.1 mm long, the rays 8-16, 0.05-0.1(-0.15) mm long, the midpoints reduced or a mere bump, unarmed on both surfaces; the primary veins not visible or 2-4 pairs, the tertiary venation not visible to the naked eye; base cordate to attenuate; apex rounded to acute; petiole 0.2-1.3 cm long, 1/3 as long to equal in length to the leaf blade, narrowly winged to almost filiform, sparsely stellate-pubescent, unarmed. Inflorescences apparently lateral, 1.5-4 cm long, unbranched, with 1(-2) flowers, 1(-2) flowers open at any one time; peduncle absent; pedicels 0.5-3 cm long, erect, filiform, protruding beyond the leaves, articulated at the base, moderately stellate-pubescent to glabrescent, unarmed; pedicel scars spaced 1-4 mm apart. Buds narrowly ellipsoid, the corolla strongly exserted from the calyx before anthesis. Flowers 4-5-merous, apparently all perfect. Calyx 2-4 mm long, the lobes 0.5-2 mm long, ca. 1 mm wide, deltate to narrowly deltate, apically obtuse to acuminate, sparsely stellate-pubescent, unarmed. Corolla 0.9-1.6 cm in diameter, mauve to purple, stellate, lobed 2/3-4/5 of the way to the base, the lobes 3-6.5 mm long, 1.2-2 mm wide, deltate, reflexed or spreading, stellate-pubescent abaxially, the trichomes porrect, sessile, the rays 8-15, up to 0.1 mm long, the midpoints shorter than the rays or reduced to bulbous base. Stamens equal; filament tube ca. 0.1 mm long; free portion of the filaments 0.5-0.7 mm long; anthers 3-5 mm long, yellow, spreading, tapering, poricidal at the tips, the pores distally directed. Ovary glabrous or with 1-2 stellate trichomes near the apex; style 0.8-0.9 cm long, filiform, curved, glabrous. Fruit a globose berry, 1(-2) per infructescence, 0.6-0.8 cm in diameter, the pericarp thin, glabrous, red at maturity; fruiting pedicels 1.5-3.5 cm long, 0.3-0.4 mm in diameter at the base, 1.5-2 mm in diameter at the apex, herbaceous, pendulous, unarmed; fruiting calyx weakly accrescent, elongating to 3-5 mm long, covering 1/4-1/3 of the mature fruit, unarmed. Seeds ca. 10-20 per berry, 1.8-3 mm long, 1.5-2.2 mm wide, flattened-reniform, dark brown to almost black, the testal cells somewhat sinuate in outline. Chromosome number: n = 12, 2n = 24 ( Kumar and Subramaniam 1987, as S. gracilipes ).

Distribution

(Fig. 15 ). Solanum cordatum occurs from northeastern Africa and the Arabian Peninsula to Pakistan and western India (Punjab, Gujarat, Maharashtra). The record of S. cordatum from Tamil Nadu ( Ramachandran and Viswanathan 2010) is based on mis-identified specimens of S. wightii .

Ecology and habitat.

Solanum cordatum occurs in grassland, bushland, and open woodland on silty, sandy, or stony soil; low elevations (not recorded for India, from sea level to 1,500 m fide Vorontsova and Knapp 2016).

Common names and uses.

None recorded from the region (see Vorontsova and Knapp 2016 for Africa).

Conservation status

( Knapp 2021a). Solanum cordatum has been formally assessed as a species of Least Concern (LC; https://www.iucnredlist.org/species/186619213/186619254).

Discussion.

Solanum cordatum appears to be much less commonly collected in western India than is the very similar and sympatric S. forskalii . It differs from S. forskalii in its compact multangulate stem pubescence of trichomes with many very short (<0.1 mm long) rays, S. forskalii has porrect-stellate trichomes with fewer rays that are marginally longer (> 0.15 mm long); stems of S. cordatum appear white dotted from the stubby trichomes. Leaf petioles of S. cordatum are decurrent and narrowly winged, while leaves of S. forskalii are distinctly petiolate. The calyx lobes of S. cordatum are longer and narrower than those of S. forskalii , while anthers are shorter in S. cordatum (3-5 mm versus 4.5-7 mm).

In eastern Africa, S. cordatum is deciduous in the dry season, growing opportunistically during times of moisture ( Vorontsova and Knapp 2016). This may be part of the reason for its relatively fewer collections in India than S. forskalii ; this species has more robust leaves that are not deciduous. Wood (1997) suggested that S. cordatum was an "Indian species which extends west to Yemen but is only found in Africa in Somalia." It is indeed found only in the Horn of Africa (Somalia, Ethiopia, and northern Kenya).

Ramachandran and Viswanathan (2010) reported S. cordatum from Sethukadai in the Namakkal District of Tamil Nadu, far from its known range in India. This report is based on mis-identified specimens of S. wightii ; the description in Ramachandran and Viswanathan (2010) appears to be a mixture of elements from published descriptions of S. cordatum and the actual specimens of S. wightii they used as their new record.

Specimens examined.

See Suppl. materials 1-3.

Figures

Figure 14. Solanum cordatum Forssk. Herbarium specimen collected in India (Badami 114, E 00757243). Photograph credit: Royal Botanic Garden Edinburgh.

Figure 15. Distribution of S. cordatum.