Solanum schimperianum
Not known.
Northeastern Africa and across the Middle East to India; fairly common around the Red Sea; growing in roadside thickets, rocky slopes, and disturbed areas, on sand or clay, usually in the shade; 1500-2800 m elevation.
Solanum schimperianum is a member of the Old World clade of the spiny solanums (Leptostemonum; Levin et al. 2006); within that it belongs to the Giganteum Clade and is related to Solanum schumannianum and Solanum schleibenii (Vorontsova et al. 2013).
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.
Lester, R. N. 1997. Typification of nineteen names of African Solanum species described by A. Richard and others, including S. campylacanthum and S. panduriforme. Bot. J. Linn. Soc. 125: 273-293.
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
Wright, C. H. 1906. Solanaceae. In Flora of Tropical Africa vol. 4(2), ed. W. T. Thiselton-Dyer, 207-261. Kew: Royal Botanic Gardens, Kew.
Local Names. Somalia: Karireh (Hemming 35), Kararete (Hemming 1911).
Solanum schimperianum is a medium-sized shrub with uniform, entire ovate leaves and dense clusters of red-orange to red berries. The inflorescences are condensed on short peduncles with short rachises while the pedicels are long and the whole inflorescence can resemble an umbel. It seems that the habit can vary between erect and scandent. The majority of stellate trichomes on the abaxial lamina have 5-10 rays, with occasional appearances of multangulate trichomes with 15-20 densely packed rays. These trichomes are predominantly on the veins or leaf margins, but also occur on stalks on the main lamina. Leaves have been reported as sticky, most likely due to the minute gland-tipped hairs mixed with the larger stellate trichomes. The African populations are generally smaller-leaved and vary between densely stellate-pubescent and almost glabrous; populations in Arabia are usually almost glabrous with larger leaves. Unusual small-leaved specimens have smaller inflorescences and can be difficult to recognize as S. schimperianum: these occur both in Africa (e.g. Hemming 35, Somalia, K) and the Middle East (e.g. Collenette 1251, Saudi Arabia, K). Occasional collections have some leaf lobing on fertile branches, e.g. Henry 20/76 (Yemen, K) and Collenette 7385 (Saudi Arabia, K).
The vegetative and fruiting morphology of S. schimperianum is deceptively similar to the zygomorphic-flowered S. somalense and the two species have suffered from historic confusion after C. H. Wright (1906) cited specimens of S. somalense as S. carense, a synonym of S. schimperianum. When flowering material is available it is obvious that S. schimperianum has pale mauve rotate flowers 1.3-2 cm in diameter and equal anthers 3.5-4.5 mm long, while S. somalense has deep mauve to purple zygomorphic flowers 2-3 cm in diameter with 4 anthers 5-8 mm long and the lowermost anther 8-11 mm long. Identifying the two species without flowers is more difficult; S. schimperianum can be distinguished by its erect to scandent or scrambling habit (versus habit always erect in S. somalense), orange-red to red berries (versus bright orange berries in S. somalense), and smaller seeds 2.5-3.8 × 2-2.8 mm (versus in 3.8-5 × 3.5-3.8 mm S. somalense). Solanum schimperianum usually has wider leaves than S. somalense. Both species occur in northern Somalia but they are not sympatric, as S. schimperianum occurs at higher elevations at 1500-2800 m while S. somalense is found at 0-1300 m elevation.
The closest relative of S. schimperianum is almost certainly the variable southern species S. tettense. Solanum schimperianum and S. tettense are mostly allopatric; both species occur in Somalia but S. schimperianum is in the northern mountains while S. tettense is only found in the southernmost tip of the country. Solanum tettense is common in Ethiopia’s Sidamo Region and one specimen of S. schimperianum is also known from Sidamo but at higher altitude than S. tettense. The two species also occupy different altitudinal belts; no intermediate specimens have been seen. Solanum schimperianum and S. tettense can have the same number of flowers per inflorescence but the inflorescence structure is different. Solanum schimperianum can be distinguished from S. tettense by its peduncles 0.3-1.5 cm long (versus peduncles 1.5-4.5 cm long in S. tettense), rachis 0.5-1(2) cm long (versus rachis 1.5-6 cm long in S. tettense), pedicels (0.8)1-2.3 cm long (versus pedicels 0.4-1(1.5) cm long in S. tettense), lack of prickles (versus deltate prickles often present on older stems of S. tettense), and largely concolorous membranous leaves (versus strongly discolorous chartaceous leaves in S. tettense).
Of the syntypes mentioned in the protologue, we have chosen the G-DC duplicate of Schimper 838 (G00145078) as the lectotype of S. carense as it is the sheet most unambiguously and explicitly mentioned; the other collection mentioned is an un-numbered collection of Schimper’s from Hohenacker’s 1842 distribution set of those collections.