Solanum forskalii
Not known
Fairly common in the Arabian Peninsula and northeastern Africa southwards to Kenya. The few collections from India and Pakistan may represent accidental introductions. The distribution appears disjunct with one known collection from Senegal and no records between Senegal and Sudan; this may be due to the relative paucity of West and Central African Solanum collections examined. Occurs in scrub on stony ground and rocky slopes, often on granite from 0-2000 m elevation.
Solanum forskalii is certainly a member of the Old World Clade within subgenus Leptostemonum (Levin et al., 2006).
Jaeger, P.-M.L. 1985. Systematic studies in the genus Solanum in Africa. PhD thesis, University of Birmingham, United Kingdom.
Levin, R.A., N.R. Myers, & L. Bohs 2006. Phylogenetic relationships among the "spiny" solanums (Solanum subgenus Leptostemonum). Amer. J. Bot. 93: 157-169.
Prain, D. 1896. Noviciae Indicae XIV. Some additional Solanaceae. J. Asiatic Soc. Bengal, Pt. 2, Nat. Hist. 65: 541-543.
Wood, J.R.I. 1984. Eight new species and taxonomic notes on the flora of Yemen. Kew Bull. 39: 123-139.
Wood, J.R.I. 1997. A handbook of the Yemen flora. Royal Botanic Gardens, Kew, United Kingdom.
Local Names. Egypt: Milâdôb (Bishari tribes, Khattab 6303); Akra kwati (Murray 3744), Akarkawatîb (Shabetai F.1753 bis). Sudan: Akra-kwateib (Cooke 127). Somalia: Mayijoblih (Griffith 99), Ghŏdhănyāley (Haud 78). Ehtiopia: Me’ih Godlech (meaning snake tooth, Hemming 152). Kenya: Lodongamuroi (Turkana language, Mathew 6796, 6553).
Solanum forskalii can be recognized by the dense white indumentum of porrect-stellate trichomes on its young stems, and the abundant prickles. The variability within this species includes long and branched inflorescences with 5-20 flowers in Sudan, Egypt and Ethiopia, and smaller 1-5-flowered inflorescences in Somalia and Kenya. The prickles are yellow, strongly curved, and very large in specimens from Egypt and Saudi Arabia but smaller, gently curved, and whitish or brown in specimens from Kenya. The trichomes are largely sessile with short midpoints for most of its distribution, but the midpoints extend to 1 mm in plants from some Egyptian populations.
Solanum forskalii is frequently confused with the largely sympatric S. cordatum. Wood (1984, 1997) and Jaeger (1985) distinguished S. forskalii and S. cordatum primarily by the numbers of flowers per inflorescence and did not note indumentum characters. Solanum forskalii can be distinguished from S. cordatum more reliably by its porrect trichomes with 6-10 rays over 0.15 mm long on the young stems (versus multangulate 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). There is a clear morphological distinction between the two species in Saudi Arabia and Ethiopia, where S. forskalii has branched many-flowered inflorescences and dense indumentum. The separation is less clear in Somalia, Kenya and the southern Arabian Peninsula; S. forskalii is more variable there with fewer flowers per inflorescence and smaller leaves. Carter & Stannard 583 from the northern Kenya appears morphologically intermediate between the two species, with long-rayed porrect stem trichomes and anthers ca. 7 mm long like S. forskalii,but leaf morphology similar to S. cordatum. Solanum cordatum grows in grassland or open woodland, sheds foliage during drought, and displays opportunistic growth in wet periods, while S. forskalii grows in more open and rocky habitats, preserving water throughout the dry season with its dense indumentum cover and tougher tissue.
In Somalia S. forskalii is sympatric with S. cymbalariifolium, and can be distinguished by its porrect-stellate trichomes on the young stems (versus simple hairs up to 1.5 mm long on the young stems of S. cymbalariifolium), and actinomorphic flowers (versus zygomorphic flowers in S. cymbalariifolium).
Solanum hadaq was cited by Wood (1984, 1997) and Jaeger (1985) as a synonym of S. cordatum but we place S. hadaq in synonymy under S. forskalii due to its porrect long-rayed trichomes on the young stems and three-flowered inflorescence of the type specimen. Of the the three duplicates of Deflers 377 at P we have selected with the locality information matching that of the protologue and that bears both flowers and fruit (P00051780).
In describing S. scindicum, Prain (1896) cited four specimens (Stolizcka s.n., Stocks s. n., Cooke s. n. and King s. n.) from the India/Pakistan border area in the Kolkata herbarium (CAL). Of these, Cooke s. n. (CAL0000018701) is also represented by a duplicate at K (K000441223) and has both flowers and fruits; we selected this as the lectotype.
Two specimens, one at B and the other at Z, were cited in the protologue of Solanum albicaule var. parvifrons; that at B was destroyed, and searches at Z failed to find the duplicate of Pfund 407 cited. We have found no other duplicates of this gathering, but have left the name untypified in the hopes that the Z duplicate will eventually be found.