Solanum nigriviolaceum
Not known
Endemic to southeastern Kenya; open ground, grassland and forest edges on hillsides, often locally common, 2500-3000 m elevation.
Solanum nigriviolaceum is a member of the Old World clade of subgenus Leptostemonum (the spiny solanums; Levin et al. 2006) . Within that it belongs to the large, unresolved Anguivi Grade (Vorontsova et al. 2013).
Bitter, G. 1923. Solana Africana. IV. Spec. Nov. Regni Veg. Beihefte 16: 1-320.
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, and L. Bohs. 2006. Phylogenetic relationships among the “spiny solanums” (Solanum subgenus Leptostemonum, Solanaceae). Amer. J. Bot. 93: 157-169.
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
Local Names. Kenya: Labotwet (Kipsigis language), Oldulili, Ol’dulele, or Endulele (Masai language), Ochok (Kairrondo language).
Uses. Roots used medicinally.
Solanum nigriviolaceum is handsome plant with large purple flowers, yellow prickles, and purple-black young shoots. It is a distinctive eastern African highland endemic with the unique combination of corollas up to 5 cm in diameter, anthers 7-9 mm long, prominent straight prickles, and trichomes with midpoints 1.5-2.5 mm long on all parts of the plant. Herbarium material of S. nigriviolaceum is frequently annotated as S. sessilistellatum. The two names were published simultaneously by Bitter (1923) and S. sessilistellatum has since been in common use from Bitter’s description, although no extant original material is known. Jaeger (1985) found that specimens annotated as S. sessilistellatum matched the type material of S. nigriviolaceum. As these names were published at the same time neither one has automatic priority and neither has been used in the published literature although both names appear in the annotations of many herbarium sheets. We choose S. nigriviolaceum because of type specimen availability. The epithet “nigriviolaceum” is more descriptive and less likely to be confused with similar epithets.
Collections of S. nigriviolaceum are commonly confused with S. aculeatissimum and S. dasyphyllum, both of which are common in the eastern African highlands. Solanum aculeatissimum has similar purple stems, hirsute appearance, abundant long straight prickles, and sometimes similar leaf shape, and but its flowers are much smaller with a more deeply lobed white corolla, and its trichomes are simple rather than stellate as in S. nigriviolaceum. Solanum dasyphyllum has similar straight prickles and elongated midpoints but its leaves are larger with secondary lobing and attenuate leaf bases, and its flowers have less dissected corollas and finer pedicels.
The large corollas and anthers combines with high prickle density in S. nigriviolaceum are reminiscent of S. richardii, which is easily distinguished by its curved prickles and a more southern lowland distribution. The South African Solanum linnaeanum is somewhat similar to S. nigriviolaceum with its abundant straight prickles and sturdy habit, but its leaves are more deeply lobed.