What Does It Look Like?
What is it?
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.
Flower colour
White
Growth form (weed type/habit)
Robust, bushy herb with short-lived perennial root system and annual aerial parts
Where it currently grows? Preferred habitat
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).
Are there similar species?
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).