Quick Facts

Quick facts

• Thunbergia (Thunbergia annua) is an upright or sprawling, short lived herb possibly occurring in marshy areas.
• It is a potential weed of crops and rangelands in tropical, subtropical and semi-arid areas.
• It is not recorded as a weed in Australia, and only doubtfully occurs outside of its native range in tropical Africa.
• Thunbergia annua is similar to, but easily distinguished from other Thunbergia species.

What Does It Look Like?

What is it?

Thunbergia (Thunbergia annua) is a small upright or sprawling herb usually growing less than 50 cm tall. The stems have long white hairs when young. The stalkless leaves are up to 20 cm long and 2 cm wide and arranged in opposite pairs. The leaf margins are not toothed but entire and there are hairs present on the veins of the lower surface only.

The flowers are white and single and occur in the angle between the leaf and stem. The flower tube is enclosed by two egg-shaped and keeled bracts (modified leaves) which could be mistaken for the calyx (outer whorl of sepals, modified leaves, of the flower); the keel of the bract is hairy. The flower is up to 1-2 cm long, only just longer than the bracts. The flower has five lobes which are each about 5 mm long and four pollen bearing stalks (stamens).

The fruits are enclosed by the two persistent bracts and consist of an orb-shaped basal portion containing the 1-2 smooth seeds topped by a narrow beak (Thiselton-Dyer 1900; Broun & Massey 1929; Andrews 1956; Barker 2008 pers. comm.).

For further information and assistance with identification of Thunbergia annua, contact the herbarium in your state or territory.

Flower colour

White

Growth form (weed type/habit)

Shrub

Where it currently grows? Preferred habitat

Thunbergia is most likely to be found in marshy areas (Thiselton-Dyer 1900; Broun & Massey 1929). It is a potential weed of crops, disturbed sites and rangelands in tropical, subtropical and semi-arid areas according to Navie (2004), but no support for this statement has been found (Barker 2008 pers. comm.).

Are there similar species?

Thunbergia is not easily confused with the very aggressive blue flowered climbers T. grandiflora and T. laurifolia since it is an annual, erect or sprawling plant generally only reaching about 20 cm high. It also has white flowers (Barker 1986).

Thunbergia (T. annua) has white flowers like T. fragrans and T. arnhemica but the latter two species, which are possibly indistinguishable from each other, twine within the vegetation at ground level and have stalked leaves. Thunbergia (T. annua) is not a twiner and it has stalkless leaves (Barker 1986).

Why Is It A Weed?

What are its impacts?

Nothing is known of any potential negative impacts of Thunbergia, which may not occur outside its native habitat in tropical Africa (Barker 2008 pers. comm.).

How does it spread?

Information about the dispersal of Thunbergia seems to be unavailable, although it is assumed that it reproduces by seed. Reproducing by formation of roots at any nodes in contact with the soil is very common amongst the members of the Acanthaceae family, but it is unknown whether this species might reproduce in this way (Barker 2008 pers. comm.).

What is its history in Australia?

Thunbergia has not been recorded from Australia and no evidence could be found for it having any particular weed potential; it would appear to be very different in character from the other species of Thunbergia already established as vigorous weeds in Australia (Barker 2008 pers. comm.).

How To Manage It?

Best practice management

Chemical control: Nothing is known about control of Thunbergia, however other Thunbergia species can be controlled with herbicides (Land Protection 2007).

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

From its name, Thunbergia is presumed to be an annual plant that reproduces by seed (Navie 2004).

Where Is It Found?

Which states and territories is it found?

Not naturalised in any Australian states or territories

What areas within states and territories is it found?

Thunbergia is not yet recorded as a weed in Australia (Jordan 2007; Barker 2008 pers. comm.).

Where does it originate?

Thunbergia annua is documented as being native to the upper Nile area (Ethiopia and Sudan) (Thiselton-Dyer 1900; Broun & Massey 1929). It possibly also occurs in Zimbabwe (Hyde & Wursten 2004).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

QLD, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Thunbergia annua

Other scientific names (synonyms)?

Does it have other known common name(s)?

Thunbergia