Solanum viarum

Species

Solanum viarum Dunal

Family

Solanaceae

Common names

tropical soda apple

Disseminule

seed

Description

Fruit a berry with 180 to 420 seeds. Seeds lenticular, subcompressed, outline obovate or broadly elliptic to nearly round, ca. 2–2.8 mm long, 1.8–2.1 mm wide, 0.5–0.8 mm thick, cross section spindle-shaped. Testa softly glistening, light to dark red-brown, finely reticulate, but appears pebbled. Hilum marginal, a narrow linear to spindle-shaped whitish slit, flush and closed, or with a depression or small hole(s), 0.7–0.9 mm long; may be subbasal or in notch depending on shape of seed. Embryo linear, spirally coiled, seen three times in cross section; endosperm readily visible.

Identification considerations

Solanaceae seeds of moderate size (over 1.5 mm long) are often difficult to distinguish from one another. Characters that may aid in identification are size range, seed outline, surface reticulation (if visible), hilar shape, and embryo shape. Testa color is not a reliable character, as it may be affected by aging and length of time spent in a mature berry.

Compare with:

Lycium ferocissimum Miers

Solanum elaeagnifolium Cav. (non-FNW)

Solanum tampicense Dunal

Solanum torvum Swartz

Distribution

India, Nepal, Mexico, Greater and Lesser Antilles, areas of Africa and South America, United States

native to South America (Argentina, Brazil, Paraguay, Uruguay)

Habitat

a weed in agricultural fields, groves, pastures, ditches, disturbed sites, natural areas

General information

Solanum viarum is a prickly perennial up to 2 m tall. In the U.S. S. viarum first appeared in Florida and has since spread to adjacent states. It has become a major concern in Florida’s agricultural and natural areas. It can form huge monocultural stands, crowding out forage and native species and preventing cattle from seeking shade. Seeds are dispersed by cattle and wildlife that eat the fruit. The plant can regenerate from its roots. In India, S. viarum is grown as a source for steroids.