Datura
Sp. Pl. 1: 179. 1753.
Herbs, annual or perennial, taprooted, usually tuberous in perennial species, usually pubescent, sometimes glabrous. Stems dichotomously branching. Leaves alternate, sometimes appearing subopposite on flowering branches; blade entire to sinuate-dentate or lobed. Inflorescences terminal, often appearing leaf-opposed, solitary flowers. Flowers 5-merous (erect); calyx cylindric, 5-toothed or splitting irregularly to produce a variable number of unequal teeth, circumscissile in fruit leaving a basal remnant that is slightly accrescent or not; corolla white to purple, radial, funnelform or trumpet-shaped, with 5 acuminate lobes (each subtended by 3 prominent veins) alternating with either lobules or shallow sinuses; stamens equal, inserted in proximal 1/2 of corolla tube; anthers basifixed, linear-oblong, dehiscing by longitudinal slits; ovary 2-carpellate (2- or 4-locular); style filiform, equaling, slightly longer, or shorter than stamens; stigma subcapitate, 2-lobed. Fruits capsules, 4-valved or irregularly dehiscing, ovoid, (2- or 4-locular, smooth or with prickles or tubercles). Seeds 40–120(–400), reniform or subreniform (black or tan-brown, with or without convex marginal ridge, some species with a white caruncle). x = 12.
Distribution
North America, Mexico, West Indies, Central America, n South America, introduced nearly worldwide.
Discussion
Species 14 (8 in the flora).
The large flowers and evening fragrance have assured the cultivation of Datura spp., in particular, D. innoxia, D. metel, D. stramonium, and D. wrightii, throughout the world. Nocturnal anthesis lasts only one night in wild species. Some species of Datura are a sacred component of Native American ritual passage and have been employed since pre-Columbian times (W. E. Safford 1922; W. J. Litzinger 1981; C. E. Boyd 2003). Indigenous and Hispanic peoples employ some species in traditional healing practices for treating wounds and inflammations and for psychotropic effects. Tropane alkaloids, of which more than 30 have been reported in Datura (E. Eich 2008), cause delirium. In particular, atropine, hyoscyamine, and scopolamine are responsible for the anticholinergic properties of some pharmaceutical preparations used in treating motion sickness, broncho- and vasoconstriction, and other ailments.
Some species of Datura have become worldwide weeds (K. Hammer et al. 1983). The commerce of various crop seeds contaminated by D. stramonium is one of the principal causes of its spread during the last century.
Poisonings and deaths from consumption of seeds and/or foliage of Datura spp. are reported for livestock (cattle, horses, swine, and chickens) and humans.
Mexico is considered the center of origin and diversification of Datura (D. E. Symon and L. A. R. Haegi 1991). Prior to human settlement, species of Datura native in what is today southwestern United States included D. discolor, D. innoxia, D. quercifolia, and D. wrightii. Pre-Columbian dispersion of D. wrightii (as a sacred and medicinal plant) and of D. stramonium (as a medicinal plant and a weed associated with Mesoamerican agriculture) is related to settlement histories and migration of various indigenous peoples. Pre-Columbian presence of D. metel (R. Geeta and W. Gharaibeh 2007) and D. stramonium (A. Touwaide 1998) in Eurasia is supported by iconographic, literature, and linguistic sources.
The polymorphism in trichome morphology (for example, glandular versus non-glandular hairs) and density has been shown to have a genetic basis that responds to selection pressures of insect herbivores (N. M. van Dam et al. 1999). Certain seed characters of taxonomic importance such as caruncles (external food bodies rich in amino acids and sugars, also known as elaiosomes) are key to ant-Datura mutualism and maintenance of wild plants populations (D. J. O’Dowd and M. E. Hay 1980). Because of distinctive patterns of variation, certain species of Datura serve as experimental organisms contributing to understanding chromosome diversity, host plant and herbivore interactions, and relationships between various floral characters and hawkmoth pollinators (A. G. Avery et al. 1959; P. L. Valverde et al. 2001; J. L. Bronstein et al. 2009; respectively).
Selected References
None.
Lower Taxa
Key
| 1 | Corollas usually 4–11 cm, limb with sinuses alternating with acuminate lobes; capsules erect. | > 2 |
| 2 | Leaf blades elliptic to narrowly ovate, margins usually pinnately lobed, sometimes sinuate-dentate. | Datura quercifolia |
| 2 | Leaf blades broadly ovate, margins usually sinuate-dentate, sometimes pinnately lobed. | > 3 |
| 3 | Corollas 4–6 cm; capsule prickles unequal, some 15+ mm. | Datura ferox |
| 3 | Corollas (5–)6–11 cm; capsule prickles ± equal, to 15 mm. | Datura stramonium |
| 1 | Corollas usually greater than 10 cm, limb with lobules alternating with acuminate lobes; capsules pendent. | > 4 |
| 4 | Corolla limbs with lobules larger than acuminate lobes, throat with purple ring; capsules with prickles, dehiscing by 4 valves, pericarp dry. | Datura discolor |
| 4 | Corolla limbs with lobules smaller than or of similar size as acuminate lobes, throat without purple ring; capsules with or without prickles, dehiscing irregularly, pericarp fleshy. | > 5 |
| 5 | Leaf blades narrowly ovate to lanceolate; corolla surfaces usually waxy; calyces glabrous, tube split along 1 side, (appearing spathe-like), with poorly defined teeth; capsules without prickles or tubercles. | Datura ceratocaula |
| 5 | Leaf blades ovate; corolla surfaces not waxy; calyces hairy, tube cylindric, 5-toothed; capsules with prickles or tubercles. | > 6 |
| 6 | Stems sparsely hairy, glabrescent; corollas white, purple, or yellow, with single, double, or triple whorls; capsules tuberculate. | Datura metel |
| 6 | Stems usually hairy, sometimes glabrescent or glabrous; corollas white, sometimes lavender or purple-tinged, with a single whorl; capsules with prickles. | > 7 |
| 7 | Corolla limbs with lobules ± equal to acuminate lobes; calyces villous (especially along veins); abaxial leaf surface villous (especially along veins), hairs spreading. | Datura innoxia |
| 7 | Corolla limbs with lobules smaller than acuminate lobes; calyces canescent (especially along veins); abaxial leaf surface canescent (especially along veins), hairs appressed or curved. | Datura wrightii |