Solanum polygamum
Not known
Found in the central Caribbean on St. Thomas, St. Jan and St. John (US Virgin Islands), Tortola and Virgen Gorda (British Virgin Islands), Isla Vieques off Puerto Rico, in eastern Cuba and on southern Hispaniola from 0-350 m in limestone and sandy areas.
Solanum polygamum is a member of the large Leptostemonum clade (Weese & Bohs, 2007), but its relationships in the group are unclear. Both plastid and nuclear sequence data are difficult to align with the rest of Solanum (L. Bohs, pers. comm.). Whalen (1984) included it in his “unusual species” group, but suggested its affinities lay with the Solanum yucatanum and Solanum crotonoides species groups.
Vahl, M. 1794. Symbolae Botanicae, part 3.
Nicolas Möller & Son, Copenhagen.
Whalen, M.D. 1984. Conspectus of species groups in Solanum subgenus Leptostemonum.
Gentes Herbarum 12 (4): 179-282.
Knapp, S., V. Persson & S. Blackmore 1998. Pollen morphology and functional dioecy in Solanum (Solanaceae).
Plant Systematics and Evolution 210: 113-139.
Weese, T.L. & L. Bohs 2007. A Three-Gene Phylogeny of the Genus Solanum (Solanaceae)
Syst. Bot. 32(2): 445-463.
Solanum polygamum is one of the few documented dioecious species of Solanum, and with S. crotonoides, the only confirmed dioecious Caribbean species in the genus (although other taxa are thought to be dioecious based on flower morphology, e.g. S. dendroicum, S. punctulatum etc.). Flower morphology in S. polygamum is the most extreme of any dioecious solanum (see Knapp et al., 1998), with the female flowers having withered anthers containing no pollen grains. Vahl (1794) suggested S. polygamum might be dioecious based on West’s field observations: “Flores alii masculi alii hermaphorditi Dn. West, ego tantem masculos vidi, an potius dioica?” Plate 55 in Symbolae botanicae (Vahl, 1794) is of a male plant.
The large, pubescent fruit of S. polygamum is similar to those of the members of section Lasiocarpa (e.g. S. quitoense, S. lasiocarpum, S. candidum). Vegetatively, however, S. polygamum is very different from those taxa, all of which have large, repand leaves. DNA sequences from S. polygamum were very difficult to align with other solanums (L. Bohs, pers. comm.) and to date, this species is of uncertain relationships.