Solanum hastifolium

Solanum hastifolium is a widespread polymorphic weedy species recognized by its lobed leaves, retrorse or recurved prickles, and inflorescences with more than 2 flowers. Sudanese collections more often mention S. hastifolium as a climbing plant, while we have only seen it growing as a shrub in Kenya. Ethiopian collections tend to have more entire leaves. The type collection is uncharacteristic of S. hastifolium; its leaves are more strongly hastate than typical, and its habit is more climbing. Friis et al. (2010) consider S. hastifolium endemic to the Somalia-Masai phytogeographical region but its distribution extends west into the Sudanian phytogeographical region (White 1983, Jaeger & Hepper 1986).

Solanum hastifolium is morphologically similar and apparently closely related to S. glabratum, S. setaceum, and S. taitense. Solanum taitense and S. setaceum occur within the distribution of S. hastifolium. Both are locally common and uniform species that are morphologically similar to some forms of S. hastifolium. Solanum setaceum is easy to distinguish by the filiform bristles on its young stems. Solanum taitense is more difficult to distinguish reliably, as no single character separates all the specimens, but S. hastifolium has the majority of the following: lobed leaves 2.6-6.5 cm long (versus entire to subentire leaves 1.2-3(3.5) cm long in S. taitense), abundant prickles 1-4 mm long, spaced 3-10 mm apart (versus inconspicuous more closely spaced prickles up to 1(2) mm long in S. taitense), more than 3 flowers per inflorescence (versus 1-2(3) flowers per inflorescence in S. taitense), corolla 1.4-2 cm in diameter (versus corolla 1-1.7 cm in diameter in S. taitense), anthers 5-8 mm long (versus anthers 4-6 mm long in S. taitense), plant sparsely to moderately pubescent (versus S. taitense densely pubescent), and trichomes sessile to short-stalked (versus stalked trichomes on all vegetative surfaces with inflated trichome stalks on the adaxial side of the leaves in S. taitense).

Solanum hastifolium is a more southerly species than S. glabratum, and where the two overlap in Ethiopia and Somalia rare collections with intermediate morphological charaters have been made.  Consistent differences between the two species include the following: S. hastifolium often has a scandent or climbing habit (versus S. glabratum always erect), fewer gray or brown recurved or hooked prickles 1-4 mm long and 0.5-3.5 mm wide (versus hooked flattened yellow prickles 2-5 mm long and 1.5-5 mm wide in S. glabratum), red fruit (versus orange or red fruit in S. glabratum), more indumentum with larger trichomes that are often stalked (versus fewer small sessile trichomes in S. glabratum), and occupies wetter environments at lower elevations. The best distinguishing character for identification purposes is the presence of a petiole in S. hastifolium (versus leaf blade decurrent at the base and a lack of a clear petiole in S. glabratum).

Jaeger (1985) suggested that S. hastifolium may be conspecific with the Indian S. trilobatum L. The two species are clearly distinct, however, and S. hastifolium can be distinguished from S. trilobatum by its more deeply stellate corolla (versus more shallowly lobed corolla in S. trilobatum), larger leaf length to width ratio (versus wider leaves in S. trilobatum), and yellow-green drying color (versus red-brown drying color in S. trilobatum).

In describing S. cynanchoides, Chiovenda (1932) did not cite a herbarium in which the type specimen was held. We have selected that in FT as the lectotype; the illustration in Chiovenda (1932) is clearly of that sheet, and that herbarium received much if not most of the material from the Italian colonial collections (although some is still held in PAL).