Prodr. 15(2): 1079. 1866.
Subshrubs, to 0.5–1 m, dioecious, rhizomatous, often forming large clumps. Stems erect or ascending, reddish-brown, much-branched, rubbery-succulent, glabrous; short-shoots common; latex watery, colorless to cloudy-whitish in young shoots, blood red in basal portions of older shoots and rhizomes. Leaves deciduous, born profusely on long and short-shoots in rainy season; stipules absent; petiole 1–2.5 cm, not stipitate-glandular; blade widely ovate-deltate, 1.8–4.6 × 1.5–2.6 cm, unlobed, base truncate, margins sinuate to weakly serrate-crenate with glands on apices of crenations in younger leaves, apex acuminate, membranous, surfaces glabrous; venation palmate. Inflorescences axillary, cymes; staminate with peduncle 0.8–3 cm, pistillate with peduncle absent; bracts 1–1.5 mm, margins entire, or sometimes with glands, glabrous. Pedicels 2–3 mm. Staminate flowers: sepals distinct, ovate to obovate, 2–2.5 × 0.8–1 mm, margins entire, apex acute, surfaces glabrous; corolla light pink to white, tubular, petals connate to 3/4 length, 5–7.5 × 1.8–2.2 mm, surfaces glabrous; stamens 10 in 2 whorls (5 + 5); filaments of both whorls distinct, outer whorl 1 mm, inner whorl 2 mm. Pistillate flowers resembling staminate, but sepals obovate, 1–2.5 × 0.8–2 mm, apex rounded; petals connate to 1/2 length, 6.5–9 × 1.8–2.7 mm; carpel 1; style 1 mm. Capsules spheric, apiculate, 1.1–1.8 × 1.1–1.8 cm, tardily dehiscent. Seeds mottled gray-brown, spheric, 12 mm diam.; caruncle rudimentary. 2n = 22.
Phenology: Flowering and fruiting spring–summer.
Habitat: Gravelly desert washes and volcanic hillsides.
Elevation: 600–1500 m.
Ariz., Mexico (Sonora)
Jatropha cardiophylla and J. dioica often have been confused because of the similarity of their spreading rhizomatous habits and red rubbery branches during the dormant season. The two species are easily distinguished by their leaves. Furthermore, J. cardiophylla is restricted to the Sonoran Desert; J. dioica is found only in the Chihuahuan Desert and areas to the east.