CABI Invasive Species Compendium (2019). Datasheet for Datura innoxia https://www.cabi.org/isc/datasheet/18004 -accessed 21 June 2021
Looking for something?Close
Downy Thornapple (Datura innoxia) is a much-branched, bushy annual or short-lived perennial herb that grows to 1 m high. The stems are dull greyish green and covered in persistent erect glandular hairs, making them clammy to the touch. The leaves are alternately arranged along the stem, stalked, dull greyish green with glandular hairs, oval in outline (widest below the middle), mostly 90-160 mm long and 65-90 mm wide, sometimes up to 200 x 120 mm, often slightly angular or with a few short, broad lobes on the margins toward the base.
The flowers are borne singly in the branch-forks; they are shortly stalked, They are 120–190 mm long, white, trumpet-shaped, with 5 short, broad lobes each ending in a narrow tip each alternating with 5 blunt angular lobes, giving the overall impression of a 10-lobed flower. There is a tubular, dull, green calyx (outer covering), extending for about half the total flower length from the base; it is smoothly rounded and has 3-6 teeth.
Downy Thornapple has capsular, prickly fruits that are bent over or hang downwards on the plant. At maturity, the fruit body is globular or almost so, 35 to 50 mm long and covered in numerous, slender prickles all more or less equal in length and mostly about 10 mm long. The capsules break up unevenly, shedding a large number of seeds or sometimes begin to open into 2–4 segments before soon breaking into uneven fragments. The seeds are D-shaped, finely pitted, with a wavy deep furrow along the margins, mid-brown to greyish brown, 4.5–5 mm long (Haegi 1976; Purdie et al. 1982; Stanley & Ross 1986).
For further information or assistance with the identification of Downy Thornapple contact the herbarium in your state or territory.
Robust, bushy herb with short-lived perennial root system and annual aerial parts
Downy Thornapple prefers open disturbed habitats, especially along watercourses or on flooded areas and in association with irrigated crops. It also grows on roadsides, on neglected sites around rural towns and near stock yards. Fertile clayey to loamy soils are preferred, but it also occurs in sandy soil (Haegi 1976; Parsons & Cuthbertson 2001; AVH 2021).
With dull greyish-green foliage, large flowers and nodding capsules, Downy Thornapple is most similar to Hairy Thornapple (Datura wrightii) but that species differs in having mostly backwards-facing non-glandular hairs on the stems and leaves, with a few erect glandular hairs, as well as flowers that are often tinged greyish lavender or greyish pink. Downy Thornapple has only erect glandular hairs on the stems and leaves and has pure white flowers. Common Thornapple and Fierce Thornapple do not have the dense covering of sticky hairs found on the stems and leaves of Downy Thornapple and also have erect (not nodding) capsules (Haegi 1976; Purdie et al. 1982).
Agriculture: Downy Thornapple is an important agricultural weed. It is toxic to stock because of the presence of a number of toxic alkaloids. The seeds are the most poisonous part of the plant. Stock do not generally graze the plants due to their bitter taste and prickly seed pods, but may be affected when they eat contaminated hay, chaff and silage. It also competes strongly with some crops, especially summer-growing and irrigated ones (Parsons & Cuthbertson 2001).
Human impacts: While all parts of the plant are toxic, no cases of poisoning in Australia have been specifically attributed to this species.
Downy Thornapple is dispersed by seed, often in water as part of run-off or along watercourses. It may also be spread as a contaminant of crop seed, in mud attached to vehicles, or by humans when it is grown as an ornamental. Dispersal through root fragments moved on machinery has also been recorded (CABI Invasive Species Compendium, accessed 21 June 2021).
The date of the first naturalization of Downy Thornapple in Australia is unknown. It was recorded from Loddon, central Victoria in 1896, then at Cobar in western New South Wales and near Brisbane in 1910 (AVH 2021). It has long been grown as a garden ornamental (though only sporadically so in Australia) and has become naturalized, probably on multiple occasions, as a garden escape.
Non-chemical control: Mechanical removal of Downy Thornapple plants is feasible for small infestations. Large stands on cropping land should be removed by ploughing or tilling the soil.
Chemical control: Small plants are susceptible to herbicide, but this method of control may be ineffective for mature plants (Parsons & Cuthbertson 2001). Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au
Downy Thornapple is a bushy herb with a short-lived perennial root system and annual aerial parts. Flowers may be produced when the plant is only 2-5 weeks old. It flowers and fruits throughout the summer and autumn, but in cooler areas the aerial parts die off and are sometimes killed by frosts in winter. In summer the plants often regrow from the semi-perennial root-system for several seasons, while in the warmer areas plants may persist through the winter.
NSW, NT, QLD, SA, VIC, WA
In Western Australia Downy Thornapple is found at scattered locations mainly in the southern wheatbelt and in the Kimberley Region; in the Northern Territory it is of very limited occurrence, mainly along the WA border adjacent to the Kimberley region; in South Australia it is found in the rural settled districts north of Adelaide as far as the Flinders Ranges; in Queensland it occurs along the length of the Great Dividing Range from Brisbane to Cairns and at a few inland localities including around Mount Isa and north to the Gulf of Carpentaria; in New South Wales it is found widely west of the Great Dividing Range; and in Victoria it is naturalised to the north and north-west of Melbourne as far as Mildura. (AVH 2021).
Downy Thornapple is native from Texas in the Untied States through Mexico and central America. It has been incorrectly recorded as native to northern South America where it occurs in cultivation and as a garden escape (see Distribution Table in CABI Invasive Species Compendium 2019).
NT, TAS, VIC, WA