SYSTEMATICS AND CHROMOSOME CYTOLOGY OF ELEUTHERINE HERBERT (IRIDACEAE)

The New World genus Eleutherine (Iridaceae, tribe Tigridieae) is treated as comprising two species that are characterized by a bulbous rootstock, a large subapical cauline leaf, and small, white, stellate, evening-blooming flowers. The more common E. bulbosa (syn. E. plicata) extends across South America from Bolivia and southeastern Brazil to the West Indies and is widely cultivated for its medicinal properties. Less well known is E. latifolia (here including E. citriodora), with centers in northern Central America and subtropical South America. Both species have a basic chromosome number of x = 6 (2n = 12) and a similar bimodal karyotype, which is distinctive in Tigridieae; all other genera of the tribe have x = 7. The common form of E. bulbosa has a heteromorphic long chromosome pair, the result of a pericentric inversion in one of the long chromosomes, and it is sexually sterile, unlike E. latifolia, which is self-compatible and autogamous. The systematics and nomenclature of the two species are dealt with in detail, and the medicinal properties of E. bulbosa are outlined.