6. Datura quercifolia Kunth in A. von Humboldt et al., Nov. Gen. Sp. 3(fol.): 6; 3(qto.): 7. 1818.
[W]
Oak-leaf jimsonweed or thorn-apple
Herbs annual, to 8 dm. Stems hairy, sometimes villous. Leaf blades elliptic to narrowly ovate, to 16 × 10 cm, margins usually pinnately lobed, sometimes sinuate-dentate, abaxial surface hairy, adaxial surface glabrescent. Flowers: calyx hairy along veins, tube cylindric, 5-toothed; corolla whitish to purple, trumpet-shaped, 4–8 cm, acuminate lobes alternating with sinuses. Capsules erect, dehiscent by 4 valves, pericarp dry, glabrous or hairy, with prickles unequal, proximals shorter than distals; calyx remnant not accrescent. Seeds black, 3–5 mm, convex marginal ridge absent, testa rugose; caruncle absent. 2n = 24.
Flowering Jul–Oct. Gardens, cultivated fields, irrigation ditches, margins of roads and trails, waste places in various types of vegetation; 0–2200 m; Ariz., Ark., Calif., Ga., Kans., La., Md., Mass., N.Mex., N.C., Okla., Oreg., Pa., S.C., Tex.; Mexico.
Datura quercifolia is native to the Chihuahuan Desert, where it hybridizes occasionally with introduced D. stramonium. In the flora area, it is native to Texas and possibly New Mexico. Its geographic range is expanding especially in agricultural habitats. Although recently documented in central California (former orange orchard in Riverside; 1984, 1996), it has not expanded its range in that state.
