Solanum anomalum
Not known.
Liberia in the west to Democratic Republic of the Congo in the east and to southern Angola; fairly common across the wet western African coastline and adjacent highland areas; growing in forest margins, thickets, beaches, roadsides and disturbed vegetation; sandy or rocky soil; 0-2000 m elevation.
Solanum anomalum is a member of the Old World clade of subgenus Leptostemonum (the spiny solanums); within that it belongs to the Giganteum clade (Vorontsova et al. 2013) and is related to S. giganteum, S. tettense and S. goetzei.
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. Nigeria: Anonomwo (Gbabwele language, Thomas 2201), Anunungwe mwo (Thomas 2020). Ghana: Nsusua Twi (Irvine 1577).
Solanum anomalum, one of the few prickly Solanum species endemic to western Africa, is an erect shrub with white stems, white deltate stem prickles, and densely clustered inflorescences appearing umbellate. The majority of collections of S. anomalum are from Ghana, Nigeria and Cameroon, but the greatest diversity of trichome morphology and leaf shape is in the southern part of the distribution in Angola. Leaves are subentire to weakly lobed throughout Liberia and Democratic Republic of the Congo but deeper lobing is observed in Angolan collections. Two collections display some characters of S. anguivi but most likely belong to S. anomalum because of their multangulate hairs: J. Gossweiler 4500 (Angola, K), has multiple prickles, apically acute leaf lobes, and ca. 18 rays on its stem trichomes; J. Gossweiler 389 (S. anomalum var. cinerascens) has ca. 15 long rays on its stem trichomes. More collections are needed from Angola to clarify the identity of these specimens.
Solanum anomalum is sympatric with the Angolan endemic S. pauperum. It can be distinguished from S. pauperum by its deltate prickles on flowering branches (versus no prickles recorded on any herbarium collections of S. pauperum), lobed leaves with cuneate bases (versus entire leaves with long-attenuate leaf bases in S. pauperum), petiole 1/6-1/4 of the leaf blade length (versus petiole 1/3-2/3 of the leaf blade length in S. pauperum), 10-20 flowers per inflorescence (versus 4-8 flowers per inflorescence in S. pauperum), pedicels 0.4-0.5 cm long (versus 0.8-1.5 cm long in S. pauperum), and white corolla (versus mauve in S. anomalum). Solanum giganteum occasionally occurs in Cameroon and Nigeria and can be distinguished by its stellate trichomes detaching as white powder, the presence of stipule-like small leaves on the stems, its discolorous leaves 12-40 cm long, and 30-150 flowers per inflorescence. Solanum anomalum is also reminiscent of the eastern African S. goetzei that has similar condensed inflorescences and glabrescent elliptic leaves, and also occurs in lowland habitats; S. anomalum can be distinguished by its deltate prickles on most specimens (versus no prickles in S. goetzei), and seeds 2.5-2.8 mm long and 2-2.5 mm wide (versus seeds 3.6-4.8 mm long and 2.8-4 mm wide in S. goetzei).
Much confusion was caused by Wright (1906) who erroneously applied the epithet “anomalum” to collections of S. aethiopicum and S. anguivi, and applied the epithet “pauperum” to collections of both S. pauperum and S. anomalum, leading to proliferation of confusing herbarium specimen determinations.
The best preserved of the five Thonning 135 duplicates at C has been chosen as the lectotype of Solanum anomalum (it is represented on IDC microfiche 2203 101: I.4). The K duplicate of Welwitsch 6105 has been chosen as lectotype of S. mannii var. compactum because Welwitsch 6105 has the best flowering material of the syntypes (other collections cited are Welwitsch 6052, 6080) and is annotated by Wright. We have chosen BM000778315 as the lectotype of S. anomalum var. trifurcatum due to its being the best quality material of the gathering, Bitter did not cite any herbaria in the protologue. The specimen of Warnecke 145 in GOET (GOET003596) is the most complete of the extant duplicates and is selected as the lectotype of S. warneckeanum. The choice of Lescrauwaet 310 as the lectotype of S. lescrauwaetii is consistent with Lester’s annotation label. The Kew duplicate of Gossweiler 389 (K000414104) is the best quality of the extant sheets we have seen and is therefore chosen here as the lectotype of S. anomalum var. cinerascens.