Solanum aculeastrum
Not known.
Upland areas across East and Southern Africa, with some occurrence in West Africa. Solanum aculeastrum appears to be most abundant across Uganda, Democratic Republic of the Congo, Kenya, and Tanzania, with a second area of common occurrence in eastern South Africa; this may be an artifact of uneven collecting, however. Forest margins, grassland, scrub, and open disturbed places at 1200-2100 m elevation, occasionally found up to 3200 m elevation.
Solanum aculeastrum is a member of the Old World clade within subgenus Leptostemonum. Its phylogenetic position within the clade is unclear, as some analyses place it as sister to S. coagulans (Levin et al., 2006) and others as sister to S. cerasiferum (Weese & Bohs, unpublished manuscript).
Dammer, U. 1905. Solanaceae africanae. Bot. Jahrb. Syst. 38(1): 57-60.
Dammer, U. 1906. Solanaceae africanae I. Bot. Jahrb. Syst. 38: 176-196.
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.
Polhill, D. 1988. Flora of Tropical East Africa: index of collecting localities. Royal Botanic Gardens, Kew.
Gonçalves, A.E. 2005. Solanaceae. In: G. V. Pope, R. M. Polhill & E. S. Martins (eds.), Flora Zambesiaca 8(4): 1-124.
Levin, R.A., N.R. Myers, & L. Bohs 2006. Phylogenetic relationships among the "spiny" solanums (Solanum subgenus Leptostemonum). Amer. J. Bot. 93: 157-169.
Commonly quoted names throughout the distribution include Mutugunda, Omutugunda, and Mutura; more rarely mentioned are Umotobo, Kood (Lateba), Niva fera-fera, Temberere, Imitobotobo (Kirundi), and Motobatoba (Ruanda).
Solanum aculeastrum is a widespread and variable shrub easy to recognize by its markedly discolorous lobed leaves that are almost white below and by its prominent (often) orange large, downwardly curved prickles. The fruit is frequently compared to lemons: big, almost always single, yellow, round or apiculate to somewhat elongated, with a tendency to develop warts. Warty fruits are most common in Uganda and in northern Democratic Republic of the Congo, but also occur sporadically in South African populations.
Solanum aculeastrum as circumscribed by recent authors (e.g. Jaeger, 1985; Gonçalves 2005) is here recognized as three species: the widespread and variable S. aculeastrum s. s., S. thomsonii with multiple small fruits from Tanzanian southern highlands, and S. phoxocarpum with markedly pointed fruits. Solanum aculeastrum can be distinguished from S. thomsonii by its 1(-3) fruits 3-5 cm long (versus 4-10 spherical fruits 1.4-1.7 cm long in each infructescence in S. thomsonii), obtuse or sometimes rounded leaf lobes (versus lobes always rounded in S. thomsonii), and calyx 3-15 mm long with acute to apiculate lobes (versus calyx 10-15 mm long with acuminate lobes in S. thomsonii). Solanum aculeastrum can be distinguished from S. phoxocarpum by its lobed, ovate to elliptic leaves 8-15 cm long and 1.5-2 times longer than wide (versus subentire elliptic leaves 6-8 cm long and ca. 2.5 times longer than wide in S. phoxocarpum), globose to elliptic or pyriform fruit less than two times longer than wide (versus pyriform pointed fruits ca. two times longer than wide in S. phoxocarpum).
It is difficult to be certain about the identity of possible S. aculeastrum isotypes as Jean Francois Drège made numerous unnumbered collections. Both sheets at K are annotated with “Temboland: between Bashee River & Morley, 1000–2000 ft”, and one of them is also labelled “Drège 1838” in different handwriting.