Thorn apples

Datura spp. Datura stramonium, Datura inoxia
Shrub
Alternate
Simple
White
Yellow
Pink
Green

D. stramonium is a rank-smelling, erect, bushy annual herb, 0.5 to 2 m tall with glabrous, green to purplish, stout stems. The roots may be shallow and extensively branched, but in some soils a stout, branched peg-like taproot with extensive stringy lateral roots can develop.

Common names 
Also known as: Common thorn apple, jimson weed, devil's trumpet, devil's weed, tolguacha, Jamestown weed, stinkweed, locoweed, datura, pricklyburr, devil's cucumber, hell's bells, moonflower,
Family 
Solanaceae
Deciduous 
No
Flowering time 
Datura stramonium generally flowers throughout the summer
Native/Exotic 
Exotic
Origin 
The native range of Datura stramonium is unclear but is probably from the tropical regions of Central and South America.
Notifiable 
No
State declaration 
Nil
Council declaration 
SIL – Special Investigation List
Known distribution 

This weed has naturalised in many areas of the world. It was introduced into Australia in the 1800's, and has become widespread in Australia, occurring in eastern Qld, N.S.W., A.C.T., Vic., eastern Tas., S.A. and south-western W.A. 

Habitat 

Thorn apples prefer warm-temperate and sub-tropical regions, mainly in open, warm situations and on fertile soils. It is often found on river flats, roadsides, agricultural lands, disturbed areas stock yards and competes strongly with summer crops. The weed is tolerant of water logging and drought.

Habit 

D. stramonium is a rank-smelling, erect, bushy annual herb, 0.5 to 2 m tall with glabrous, green to purplish, stout stems. The roots may be shallow and extensively branched, but in some soils a stout, branched peg-like taproot with extensive stringy lateral roots can develop.

Impact and control methods 

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  and several Australian states(prohibited plants that must be controlled). They serve no economic purpose and possess characteristics that are harmful to humans, animals or the environment)  In some countries of the world, it is also prohibited to buy, sell or cultivate Datura plants.

Thorn apple (recurved) competes strongly with summer species for moisture and nutrients. Although it displaces annual grasses, ground cover and riparian vegetation, it is not known to be a serious weed of natural ecosystems.

Dense infestations occur in pastures and on river flats, producing a complete ground cover. The plants die in the cooler autumn weather. However, dead plants bear capsules that may remain standing through winter into spring.

Seeds of D. stramonium are long lived, 91% surviving 39 years burial at 34 cm in one experiment 

Stem and leaves 

Thorn apple (Datura stramonium) in the seedling stage, the first true leaves are ovate with pointed tips and few or no lobes. In later stages the leaves, which have an unpleasant smell when crushed, are alternate, ovate to broadly triangular, glabrous, unevenly toothed, 5-25 cm long, 4-25 cm wide, on a petiole and up to 10 cm long.

 

Thorn apple (Datura inoxia) leaves are densely hairy, especially on the underside. They are dark green, arranged alternately along the branches, 6-20 cm long, 3-12 cm wide and with leaves tending to be borne near the branch tips. Stems are erect, branching, with fruit borne in the axils of the branches. Hairs on the stems are glandular and erect.

 

Flowers and fruits 

Thorn apple (Datura stramonium) flowers are white-lilac 6-8 cm long. Seed capsules are large and oval shaped with numerous spines varying in lengths. 

Flowers of thorn apple (Datura inoxia) are white, trumpet-shaped and 15-17 cm long. They are borne singly on short stalks in the forks of the branches and consist of five segments.

 

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 

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.