Datura metel

Datura metel is a shrub-like annual or short-lived, shrubby perennial, commonly known in Europe as Indian thornapple, Hindu datura, or metel and in the United States as devil's trumpet or angel's trumpet. Datura metel is naturalised in all the warmer countries of the world. It is found notably in India, where it is known by the ancient, Sanskrit-derived, Hindi name dhatūra (धतूरा), from which the genus name Datura is derived.

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The plant is an annual or short-lived shrubby perennial herb. The roots are a branched tap root, and are not fleshy like roots found in perennial species such as Datura innoxia and Datura wrightii. The species can grow up to 6 ft (1.8 m) high. The stems are hollow, green or purple-black, somewhat woody, and have a strong odour. It is slightly pubescent, with green to dark violet shoots and oval to broad oval leaves that are often dark violet as well. The leaves are simple, alternate, petiolate, and exhibit entire or deeply lobed margins. The pleasantly-scented 6–8 in (15–20 cm) flowers are immensely varied, and can be single or double. Corolla colour can range from white to cream, yellow, red, and violet. The seed capsule is covered with numerous conical warts or short, sparse spines. The fruits break up irregularly at maturity by not dehiscing in four equal valves like those of other Datura species. Seeds are endospermous. D. metel was first described by Carl Linnaeus in 1753, but few botanically correct illustrations were made until after the New World was settled. The original home of the plant, although long conjectured to have been India, is now known to have been somewhere in the Americas, probably the Greater Antilles. As late as 1992 it was still being claimed that the plant was "...native probably to the mountainous regions of Pakistan or Afghanistan westward..." While there now remains no doubt that the species originated in the New World, evidence is mounting that it was introduced to the Indian subcontinent - whether by human agency or some chance natural event is not known - at a date no later than the 4th century CE. This precedes the first arrival of European explorers in the Americas. A wild form of D. metel as a distinct species is unknown. The species, as currently described, is essentially a collection of ancient cultivars likely attributable to pre-Columbian horticultural practices. Similarities to D. innoxia D. metel is similar, in its above-ground parts, to D. innoxia, but, while D. metel has almost glabrous leaves and fruits that can be nodding or erect and are warty, rather than spiny; D. innoxia is pilose (softly hairy) all over and has a markedly spiny, nodding fruit with a more prominently frilled and reflexed persistent calyx. Symon and Haegi noted in 1991 the occurrence on Cuba of an apparently wild plant given the name Datura velutinosa V.R. Fuentes (no longer an accepted species and now listed as a form of D. innoxia), the capsules of which are tuberculate like those of D. metel. Historically, single-flowered forms of D. metel have frequently been confused with the widely naturalised D. innoxia - from which it differs in its much less pubescent stems and foliage and shorter-spined and less densely-spined capsules. The reason for this confusion was finally discovered through genetic research carried out in 2000, where it was determined that D. metel is a domesticated form of D. inoxia that was originally derived from Central America and southeastern Mexico. In support of this claim regarding domestication, Cavazos et al. list several pieces of evidence. While the flowers of wild Datura species are usually white or pale, thin in texture, single and short-lived, the flowers of D. metel have several distinctive strong colour forms, are thick in texture, often have double or triple flowers (trumpet-like corollas nested one within the other) and can last for up to a week before withering. Additionally, the seed capsules of wild Datura species are usually clad with sharp spines which protect them from premature predation, while those of D. metel bear short, sparse spines or tubercles. It is also found that regrowth of the perennial wild species sprouts from the top of the thick roots below ground level, while in D. metel such regrowth is sub-shrubby, sprouting from the woody stem base. It is those woody stems that are used in the vegetative propagation of this 'species' in the indigenous horticulture of southern Mexico. In the light of such evidence, it appears highly likely that humans have in the past undertaken selective breeding of the species ancestral to D. metel to produce mutant forms that flower for longer, have colourful corollas of curious shapes, fruits that lack hurtful spines and somewhat shrubby stems that lend themselves readily to the taking of cuttings. Cultivars ...it seems clear that D. metel is essentially a collection of cultivars and recent critical authors have found it impossible to recognise a wild type for the species. This view is supported by the tuberculate capsules found in D. metel (as compared with the spinose capsules of other species) and the retention of seeds on the placenta, at least in cultivars 'Fastuosa' and 'Chlorantha'. Both of these traits suggest cultivar selection...The variants of D. metel have been widely grown as ornamentals over a long period of time...There is no evidence that the variants arose from horticultural plant breeding in the Old World...These facts taken together strongly suggest that D. metel was a well-established cultivated species with a range of forms in its place of origin and that these forms arrived ready-made in Europe. A cultivar of D. metel with a glossy, purple-black stem (Hindi: काला धतूरा kāla dhatūra - "black datura") has long existed as a garden plant under the obsolete name Datura fastuosa (coined originally by Linnaeus and featuring the Latin epithet fastuosa, meaning "haughty" or "proud"). Its flowers normally have a double or triple corolla, each corolla having a deep purple exterior and white or off-white interior. The same double or triple corolla is also a feature of the yellow-flowered cultivar 'Chlorantha'. The purple-flowered 'Fastuosa' has been reported to have become naturalised in Israel, where it may yet become as common a roadside weed as the related D innoxia. D. metel 'Fastuosa' has in recent times become known under a variety of superfluous cultivar names such as 'Black', 'Blackcurrant Swirl', 'Cornucopaea', 'Double Blackcurrant Swirl', 'Double Purple', and 'Purple Hindu'. It has also received many scientific names which should not be used for a cultivar: Datura hummatu var. fastuosa (L.) Bernh. Datura fastuosa L. Datura metel f. fastuosa (L.) Danert Datura metel var. fastuosa (L.) Saff. Stramonium fastuosum (L.) Moench Likewise the yellow-flowered D. metel 'Chlorantha' has acquired such superfluous cultivar names as 'Ballerina Yellow'.

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Annual herb