Downy Thornapple

Datura innoxia

Quick facts

Status

Permitted s11

Life Cycle

Annual or short-lived perennial

Growth Form

Herb

Origin

United States, Mexico and central America

Flowers

White

Dispersal

Water, mud

Toxicity

Toxic to livestock and humans

Names

Other Common Names: Recurved Thornapple.

Synonyms: Datura inoxia, Datura meteloides, Datura fastuosa, Datura metel.

Form and function

Grows to up to 1 metre high, reaches maturity very quickly, usually within 2 to 5 weeks and produces a long-lived seedbank, with seeds capable of remaining viable in the soil for up to 40 years

Flowers

White (sometimes tinged pale purplish).
Large and trumpet shaped.
About 120 to 190 mm long.
Five broad lobes alternating with five shorter angular lobes, giving a ten‑lobed appearance.
Borne singly in the forks of branches.
Short stalks present.
Calyx tubular, dull green and extending about halfway up the flower.
Calyx with 3 to 6 small teeth.

Leaves

Broad simple leaves with glandular hairs.
Alternately arranged along the stems.
Borne on stalks.
Oval shaped.
Usually 90 to 160 mm long and 65 to 90 mm wide.
Sometimes up to 200 mm long and 120 mm wide.
Margins slightly angular or with short broad lobes near the base.
Dull greyish green in colour.
Covered with glandular hairs.

Fruits

Capsule type fruit.
Globular to almost round in shape.
About 35 to 50 mm long.
Usually bent over or hanging down.
Covered with many slender prickles about 10 mm long.
Splits unevenly at maturity into fragments or 2 to 4 segments.
Contains many seeds.

Roots

Branched root system.
Either shallow or with a taproot extending up to about 1 m deep.
Fine stringy side roots present.

Habitat

Prefers fertile clay to loamy soils but also can establish in sandy soil. Mostly found along watercourses or on flooded areas but some can be seen on roadsides and rural areas. While it been recorded around Perth, it's mostly a weed of warmer climates.

May be confused with...

Similar native species: Similar to Hairy Thornapple (Datura wrightii) but can be distinguisehd in having mostly backwards-facing non-glandular hairs on the stems and leaves and its tinged greyish lavender or greyish pink flowers.

How does it spread?

Seeds are dispersed mainly by water along watercourse or mud on the vehicles or machinery.

History

First recorded in central Victoria in 1896 after being imported as garden ornamental.

How to control

Physical

Chemical

Physical

Seedlings and small plants can be hand pulled or dug out but making sure to remove all the roots to prevent resprouting. However, since its very long seed bank persistence, manual removal should be conducted repeatedly and need to monitor regularly for early detection.

Cultivation of large infestation can be effective for seedlings. However, due to its tough roots, cultivation need to be repeated several times over many months. Avoid cultivation with fruiting plants and monitor regularly for early detection of resprout.

Chemical

Chemical treatment is effective for small plants but maybe ineffective for mature established plants.

Selective:

For young, actively growing plants, apply a mix of 285 mL 2, 4-D (700 g/L) in 100 L of water, using a foliar application method (e.g. backpack sprayer or boom sprayer), ensuring full leaf coverage.

Non-selective:

Alternatively for actively growing plants, apply a mix of glyphosate (450 g/L) using; using a handgun, spraying with a rate of 400 to 560 mL per 100 L of water or knapsack spraying with a rate of 60 to 80 mL per 15 L of water. Use higher rate on plants over 15 cm high.