Datura stramonium (Common Thorn Apple)

Scientific name

Datura stramonium  L.

Synonyms

Datura inermis Juss. ex Jacq; Datura pseudostramonium Sieb. Bernh. Tromms; Datura stramonium var. tatula (L.) Torr.; Datura stromonium var. chalybea W.D.J. Koch, nom. illeg.; Datura tatula L. ; Stramonium vulgatum Gart. Fruct. et Sem.

Common names

Common thorn apple, jimson weed, devil's trumpet, devil's weed, thorn apple, tolguacha, Jamestown weed, stinkweed, locoweed, datura, pricklyburr, devil's cucumber, hell's bells, moonflower, amaduudu (Luganda), gathumba (Kikuyu), muana (Kiswahili), ngwata (Kamba), silulu (Kitosh)

Family

Solanaceae

Origin

The native range of Datura stramonium is unclear but is probably from the tropical regions of Central and South America.

Naturalised distribution (global)

Datura stramonium  is naturalised in all the world's tropical and warm temperate regions.

Introduced, naturalised or invasive in East Africa

Datura stramonium is invasive in parts of Kenya and Uganda (A.B.R. Witt pers. obs.) and in Tanzania (Henderson 2002).

Habitat

Roadsides, agricultural lands, disturbed areas, riverbanks.

Description

Datura stramonium is an erect annual herb forming a bush up to 1-1.5 m tall.

The leaves are soft, irregularly undulate, and toothed.

The fragrant flowers are trumpet-shaped, white to creamy or violet, and 6.5 to 9 cm long. They rarely open completely. The egg-shaped seed capsule is walnut-sized and either covered with spines or bald. At maturity it splits into four chambers, each with dozens of small black seeds.

Reproduction and dispersal

The seed is thought to be carried by birds and spread in their droppings. they can lay dormant underground for years and germinate when the soil is disturbed.

Similar species

Datura ferox and Datura stramonium (common thornapple) produce erect capsules on straight stalks which contain black or grey seeds.

Datura leichhardtii, Datura metel, Datura inoxia and Datura wrightii can be differentiated from these two species as their capsules are held on a curved stalk, and they produce brown or yellow seeds.

D. ferox can be distinguished from D. stramonium by its capsule which, has about 40-60 spines of variable length.

D. ferox flower is shorter (4-6 cm long) compared to the flower of D. stramonium which is longer, up to 10 cm long.

Brugmansia species may be confused with Datura species. Brugmansias long-lived (perennial) while daturas are annual. Both plants have a trumpet shaped flower; but those of brugmansias point downwards while datura's flowers most often point upward. Brugmansias emit a sweet fragrance while datura's fragrance can be described as spicy or lemony.

Economic and other uses

Datura stramonium can be grown as an ornamental plant. It also has medicinal properties and is used as a narcotic. However, these uses cannot compensate for this plant's overall negative impacts.

Environmental and other impacts

Datura stramonium is one of the world's most widespread weeds and has been recorded from over 100 countries. It is a poisonous weed that competes aggressively with crops in the field and pasture. All parts of Datura plants contain dangerous levels of poison and may be fatal if ingested by humans and other animals, including livestock and pets. D. stramonium has been listed as a noxious weed in South Africa (prohibited plants that must be controlled. They serve no economic purpose and possess characteristics that are harmful to humans, animals or the environment) and several Australian states. In some countries of the world, it is also prohibited to buy, sell or cultivate Datura plants.

Management

The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species. Some components of an integrated management approach are introduced below.

The best form of invasive species management is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.

Isolated plants should be hand-pulled before they set seed and larger infestations can be controlled by tillage when weeds are in the seedling stage. This becomes less effective as plants mature as stems become woody plants can regenerate from the roots if they are not completely removed. Datura stramonium is susceptible to a range of soil- and foliar-applied herbicides which are commonly used for selective broadleaf annual weed control. When using any herbicide always read the label first and follow all instructions and safety requirements. If in doubt consult an expert.

Despite a great deal of research into the biocontrol potential of a number of fungi, none are currently being used in weed control programmes.

Legislation

This species has been declared a noxious weed under the Noxious Weeds Act CAP 325, in Kenya. Accordingly the Minister of Agriculture can compel land owners who have such declared noxious weeds growing on their land to eradicate or have it otherwise removed.

References

CABI Invasive Species Compendium online data sheet. Datura stramonium (jimsonweed). CABI Publishing 2011. www.cabi.org/ISC. Accessed March 2011.

Henderson, L. (2002). Problem plants in Ngorongoro Conservation Area. Final Report to the NCAA.

Editors

Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat - UK.

Acknowledgments

This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).

Contact

BioNET-EAFRINET Regional Coordinator: eafrinet@africaonline.co.ke