Jatropha dioica
Gaz. Lit. México 3(suppl.): 4. 1794.
Subshrubs, to 1 m, dioecious, rhizomatous, often forming colonies. Stems spreading, reddish brown (when actively growing) or red to dark red or grayish (when dormant), much-branched, rubbery-succulent, glabrous; short shoots common; latex watery, colorless to cloudy-whitish in fast growing shoots, blood red in basal portion of older shoots and rhizomes. Leaves deciduous, fascicled on short shoots; stipules deciduous, linear, 1–2 mm, undivided; petiole 0–0.2 cm, not stipitate-glandular; blade linear-spatulate to narrowly obovate, 1.5–5(–7) × 0.2–0.7 cm, usually unlobed, sometimes shallowly, rarely deeply, 3-lobed, base attenuate, margins entire, apex rounded, membranous, surfaces glabrous; venation pinnate (palmate if lobed). Inflorescences terminal or axillary, fascicles; peduncle absent; bracts absent. Pedicels 1–2.5 mm. Staminate flowers: sepals distinct or connate basally, ovate to elliptic-lanceolate, 2.5–3 × 1.2–1.4 mm, margins entire, apex acute, abaxial surface hairy, adaxial glabrous; corolla white to pinkish white, urceolate-tubular, petals connate most of length, 5–6 × 1.4–1.5 mm, abaxial surface sparsely puberulent abaxially, adaxial glabrous; stamens 10 in 2 whorls (5 + 5); filaments of both whorls connate from 1/5–3/4+ length, outer whorl 2–3 mm, inner whorl 3–5 mm. Pistillate flowers resembling staminate; carpel 1; style 2.5–3 mm. Capsules ellipsoidal, 1.2–1.4 × 1.1–1.3 cm, tardily dehiscent. Seeds solid gray-brown, spheric, 12 mm diam.; caruncle rudimentary. 2n = 44.
Distribution
Tex., n Mexico.
Discussion
Varieties 2 (2 in the flora).
R. McVaugh (1945b) recognized two varieties in Jatropha dioica based primarily on leaf shape; the two are not readily recognizable and probably hybridization between them has resulted in intermediate populations, as McVaugh noted. The varieties are treated here with some reservation.
Selected References
None.
Key
| 1 | Leaf blades oblanceolate to narrowly obovate, 3.5–5(–7) cm; sepals distinct; stamen filaments connate 3/4+ length; petals pinkish white. | Jatropha dioica var. dioica |
| 1 | Leaf blades linear-spatulate, 1.5–2.5 cm; sepals connate basally; stamen filaments connate to 1/4 length; petals white. | Jatropha dioica var. graminea |