Solanum arundo
Not known.
). Endemic to eastern Africa, in Somalia, Kenya, and Tanzania; common on grassland, savannah, open woodland, or sand dunes, calcareous or volcanic soil, often found on roadsides and abandoned cultivated land; 0–2000 m elevation.
Solanum arundo is a member of the Old World Clade within the Leptostemonum clade; within that group it is sister to Solanum dennekense in the Arundo clade (Vorontsova et al. 2013). The specimen labeled “S. arundo” in the analysis of Levin et al. (2006) was misidentified; its determination is still unknown.
Bitter, G. 1923. Solana Africana. IV. Spec. Nov. Regni Veg. Beihefte 16: 1-320.
Chiovenda, E. 1929. Solanaceae. In Flora Somala, Volume 1, pp. 237-242. Rome: Sindicato Italiano Arti Grafiche.
Chiovenda, E. 1932. Solanaceae. In Flora Somala, Volume 2, pp. 331-336. Rome: published by the author.
Friis, I. 2006b. Solanaceae. In Flora of Somalia vol. 3, ed. M. Thulin, 206-219. Kew: Royal Botanic Gardens, Kew.
Levin, R.A., N.R. Myers, & L. Bohs 2006. Phylogenetic relationships among the "spiny" solanums (Solanum subgenus Leptostemonum). 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
Uses. Used as a hedge plant.
Solanum arundo is a common and distinctive spiny small tree, often associated with human habitation and easy to recognize by the large flat curved prickles on its stem and long straight prickles on its leaves. Collections of S. arundo are commonly annotated as S. diplacanthum in herbarium collections as the earlier name S. arundo was not used by Bitter (1923).
Solanum arundo and the largely sympatric S. dennekense form the Arundo clade (Vorontsova et al. 2013), sharing hooked stem and straight leaf prickles, tough yellow pericarp, and white stems. Solanum arundo can be distinguished from S. dennekense by its longer leaf prickles and its elliptic clearly lobed leaves less than 2.5 cm wide, versus ovate entire or only very shallowly lobed leaves more than 2.5 cm wide in S. dennekense.
In describing Macaluso’s collections from Italian Somalia, Mattei (1908) stated that the specimens were in the herbarium of the Orto Botanico in Palermo. Searches of the herbaria in PAL have failed to locate this specimen, it is possible that the sheet has ended up in one of the other Italian colonial herbaria (FT, Naples). We refrain from neotypifying this name until a complete search has been done; the protologue is very detailed and establishes this name clearly as the oldest name available for this taxon as recognized earlier by Chiovenda (1929, 1932) and Friis (2006b).