7c. Mirabilis Linnaeus sect. Oxybaphoides A. Gray in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 173. 1859.
Allioniella Rydberg; Hesperonia Standley
Herbs, herbaceous to suffrutescent or shrubby perennial [annual]; roots cylindric, cordlike. Stems erect to decumbent or prostrate, densely to sparsely leafy, leaves ± evenly distributed. Leaves: basal leaves petiolate, larger; distal leaves short petiolate or sessile, smaller, margins entire. Inflorescences axillary and terminal in open or congested, few or repeatedly branched cymes; involucres slightly accrescent, bell-shaped, with 1(-3) flowers inserted at base. Flowers: perianth broadly and shortly funnelform, abruptly flared from narrow tube, deeply 5-lobed; stamens 3-5. Fruits with (0-)5-10 indefinite or prominent lines, ellipsoid or obovoid, round in cross section, base not or slightly constricted, apex rounded, truncate, or somewhat nipplelike, surface of fruit smooth or very slightly rugose, glabrous, mucilaginous when wetted.
Species ca. 17 (3 in the flora): sw United States, n Mexico, South America, s Asia.
Mirabilis sect. Oxybaphoides is poorly understood. It is the only section with species native to the Old World. In North America, two genera have been recognized: the monotypic Allionella, and the complex series of intergrading forms in Hesperonia, where P. C. Standley (1918) recognized nine species and A. Heimerl (1934c) referred to the group (in Mirabilis) as a "formenkreis." Most later botanists have included all taxa in the complex in a broad Mirabilis, variously treating the different morphologic entities as species, infraspecies, or variously combining them into broadly constructed, variable taxa. One species in the section, Mirabilis expansa (Ruiz & Pavon) Standley, has recently been discovered to be an important food crop among indigenous peoples of the Andes (National Research Council 1989b).
Spellenberg, R. and S. R. Rodríguez Tijerina. 2001. Geographic variation and taxonomy of North American species of Mirabilis, section Oxybaphoides (Nyctaginaceae). Sida 19: 539-570.