Shrubs [prostrate subshrubs]. Stems erect [prostrate], branched, swollen at nodes, quadrangular, becoming cylindric, [less than 1] to 4[–7] m, hairy, becoming glabrate. Leaves opposite, 2-foliolate [even- or odd-pinnately compound]; stipules persistent, herbaceous, ovate [to triangular], apex obtuse to acuminate [apiculate]; petiolules absent; leaflets [1–]2[–17], opposite [alternate], connate basally 2–4 mm (leaves appearing simple and 2-lobed) [distinct], obliquely lanceolate to falcate [oblong to ovate], equal [unequal], base angular, apex mucronate, surfaces appressed-pubescent, becoming glabrate. Pedicels in leaf axils, erect or spreading. Flowers solitary, often irregular by twisting of petals; sepals deciduous, 5, distinct, green, ± unequal, margins undifferentiated, apex obtuse, appressed-pubescent; petals deciduous, 5, imbricate, spreading, twisted, yellow, oblong to oblong-lanceolate [ovate], base clawed, apex obtuse; nectary 10-lobed; stamens 10, ± equal; filaments free, subulate, with ± equal basal scales with toothed [entire] margins; anthers sagittate, versatile; ovary short-stalked, 5-lobed, 5-locular, hirsute-pilose; ovules [6–]8 per locule; style persisting on young fruit, later deciduous, not forming beak; stigma minute. Fruits schizocarps, globose, 5-lobed, splitting septicidally into 5 mericarps. Seeds 1 per locule, brown, boat-shaped. x = 13.

Distribution

sw United States, Mexico, South America (Argentina, Bolivia, Chile, Peru), warm desert regions.

Discussion

Species 5 (1 in the flora).

Selected References

None.

Lower Taxa

Larrea tridentata