Solanum spirale Roxb.

Solanum spirale is the only Paleotropical and the only tetraploid member of section Geminata. No specimens of S. spirale have been collected in the New World, and its widespread use in India, Thailand, and Laos point to its being either native there or an old introduction. Henderson (1978) speculates on the status of S. spirale in Queensland and concludes that if it is an introduction, it has not spread as a weedy species should. Symon (pers. comm.) however, feels that the range of S. spirale is expanding in Australia, perhaps indicative of its being an introduction.

Another instance of a close relative of an otherwise Neotropical group occurring in the Old World tropics (in this case in the Society Islands) is Solanum repandum G. Forst. of section Lasiocarpa (Whalen et al., 1981; Bruneau et al., 1995). Solanum repandum however, is found only in association with humans, and may be a recent introduction (see discussion in Whalen et al. 1981).

Solanum spirale is most similar, and perhaps most closely related to S. nudum, a widespread Neotropical species (see above). It differs from that species in its larger leaves, inflorescences, buds, and flowers, and in its bright orangish-red berries. Material from Australia is tetraploid with n=24, but no authentic chromosome counts exist for S. spirale from other parts of its range. The count of n=12 (Gerasimenko & Reznikova, 1968) for plants from Bogor certainly refers to S. diphyllum, a widely cultivated species often confused with S. spirale. More living collections of S. spirale are needed to determine its relationships to New World taxa. Crossing studies would be very useful in solving this problem. Despite its brightly colored berries, S. spirale is not closely related to S. pseudocapsicum or the members of that species group. Solanum spirale differs from those species in its deflexed fruiting pedicels, flower shape, and leaf trichome morphology.

As mentioned above, Solanum spirale is widely used and cultivated in dooryard gardens in India, Thailand, and Laos. No uses appear to have been reported from Indonesia or Australia. In Assam (Knajilal et al. 1939) the roots are employed as a narcotic and diuretic, and the leaves and berries are eaten. Berries are eaten either raw or cooked, while leaves are eaten cooked. In Laos (Poilane 26074) the bark of S. spirale is broken and soaked in cold water, then used as a febrifuge for adults and infants. Other members of the S. nudum species group are also used as febrifuges in tropical America (S. pseudoquina in Brazil, S. nudum in Colombia).

Species described by Roxburgh are often difficult to lectotypify, as he did not cite specimens in the original descriptions (Sealy 1956/1957). For many of the species described in Flora indica (Roxburgh, 1820, 1824), drawings were made by native artists and these are housed at K. A drawing was not made for Solanum spirale, so this makes the choice of a lectotype difficult. Many of Roxburgh's specimens and types are in the Wallich herbarium at K (Stafleu & Cowan, 1983). I have chosen to lectotypify this species with a specimen (Fig. 57 in Knapp, 2002) in the Wallich herbarium (formerly the herbarium of the East India Company in Calcutta). Roxburgh was the curator of this herbarium from 1793 until 1813, and deposited many specimens there. The lectotype I have chosen is from Silhet, the locality cited by Roxburgh in the Flora indica ", and is the only specimen of S. spirale from that locality in the catalog of the plants in the East India Company's herbarium (Wallich, 1830). The sheet matches the description very well and is probably that collected by Roxburgh.