Quick Facts

Quick facts

• Laurel Clock Vine (Thunbergia laurifolia) is a plant native to India, Myanmar and Malaysia.
• It is a vigorous, perennial, climbing vine that is capable of smothering vegetation in tropical rainforest areas.
• Thunbergia species are a major threat to remnant vegetation in the Wet Tropics.
• Early intervention is crucial otherwise the tuberous system of roots make them difficult to remove.
• Take care when disposing of Laurel Clock Vine because garden waste is a frequent source of new weed infestations.

What Does It Look Like?

What is it?

Laurel Clock Vine (Thunbergia laurifolia) is a a vigorous, perennial climbing vine with tuberous roots. Its stems and leaves are gland-dotted. The leaves are oval-shaped, not lobed, and narrow to a pointed tip, and are mostly 130-190 mm long and 50-90 mm wide. Towards the end of the branches there are 4 trumpet-shaped flowers at each of the nodes.

The flowers are on stalks up to 17 mm long and the flower begins as a short broad tube, white on the outside with a yellowish throat, and opens out into five rounded, pale lavender-blue petals, one larger than the others. The flowers are up to 80 mm long and 60-80 mm across, and are borne in clusters on long, drooping branches.

The seed capsule (fruit) is brown and inconspicuous, oval-shaped with pinched ends (i.e. elliptical), 10 mm long and 4 mm wide. The capsules usually contain two to four hemispherical seeds which have a hollow inner surface like a cap. The seeds are less than 10 mm in diameter and covered with brown scales (Barker 1986; CRC 2003).

For further information and assistance with identification of Laurel Clock Vine contact the herbarium in your state or territory.

Flower colour

Blue

Growth form (weed type/habit)

Vine

Where it currently grows? Preferred habitat

Laurel Clock Vine is found along riverbanks, in disturbed forest areas, particularly in the margins, in open woodlands, on roadsides and fence-lines in tropical and subtropical regions (Navie 2004).

Are there similar species?

Laurel Clock Vine and Blue Trumpet Vine (Thunbergia grandiflora) are so similar that there has to be doubt that they are different species. The most useful distinction between them in Australia is the unlobed leaves of Laurel Clock Vine and the lobed leaves of Blue Trumpet Vine (Barker 1986).

Both species are major threats and have potentially the same impact on the native rainforests they invade (Navie 2004). They may be found growing together and in herbicide trials of 36 herbicides by the Queensland Department of Natural Resources and Mines there was only one herbicide which was effective against both species (CRC 2003).

Laurel Clock Vine is unlikely to be confused with the other Thunbergia species in Australia as they have different coloured flowers. T. arnhemica and T. fragrans have white-flowers while T. alata has an orange flower with a black throat. In addition, none of these have the ability to climb in the same way as Laurel Clock Vine or Blue Trumpet Vine although they can form smothering populations at ground level (Barker 2007, pers. comm.).

Why Is It A Weed?

What are its impacts?

Laurel Clock Vine is on the Alert List for Environmental Weeds, a list of 28 non-native plants that threaten biodiversity and cause other environmental damage. Although only in the early stages of establishment, these weeds have the potential to seriously degrade Australia's ecosystems (CRC 2003).

Native ecosystems: Laurel Clock Vine is a major threat to monsoon vine thickets and remnant tropical rainforests across northern Australia (CRC 2003). Its ability to climb to the top of tall trees as well as across the top of lower vegetation eventually smothers the species supporting them, often native vegetation, and may even lead to the toppling of mature trees because of the weight of the vine. It is particularly prevalent in areas on the edges of rainforest margins where light has been introduced (Navie 2004).

How does it spread?

Dispersal is by seeds, cuttings, and fragments of stems and roots; the root tubers formed can be enormous. Dumping of garden cuttings is a likely means of spread since new plants can be produced from the nodes and from the tuberous roots, or through contaminated earth being removed for fill or other soil use. Infestations along riverbanks have been caused by root pieces breaking off and being transported further downstream by floodwaters. Seed production is by far the least effective means of dispersal of the plant (CRC 2003).

What is its history in Australia?

Laurel Clock Vine has been known in cultivation in Australia since the 1960s, although it could have been here longer since it was not distinguished from Blue Trumpet Vine (Thunbergia grandiflora) until Barker brought attention to it in her 1986 publication. It was first recorded as naturalised in Queensland in 1987 (CRC 2003).

How To Manage It?

Best practice management

Control of laurel clock vine is very difficult because they can regenerate from extensive underground tubers if they are not all killed or removed (NSW DPI 2018).

Chemical control: Spraying or injecting with herbicides is often the only option and this has provided effective control in the past. However it is unlikely that one application will achieve complete eradication. Monitoring and follow-up will be needed. In Queensland contact your local government office for advice (Natural Resources and Water 2007; CRC 2003).

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

Non-chemical control: Physical control: The cutting of Laurel Clock Vines at ground level is usually not effective since plants will regenerate from their underground tubers. Small plants may be dug out, but established plants normally have very large tuber systems that are virtually impossible to remove completely.

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Laurel Clock Vine grows rapidly in tropical and subtropical climates. Its growth is checked by cold temperatures which is probably why it can be grown in southern areas of Australia without becoming the problem it is in northern Australia. Peak flowering is from September to December but flowers may still be observed outside these months (CRC 2003).

Little is known about seed formation, seed drop and germination in this species. It was originally thought that Thunbergia species in Australia might not produce viable seed, but successful germination of seeds has now been recorded from several species, including Laurel Clock Vine (CRC 2003). From observations of herbarium specimens, fruits are formed, but not prolifically, suggesting that effective pollinators of Laurel Clock Vine may not be present in Australia or that the flowers are not self-compatible (Barker 2007, pers.comm.).

Where Is It Found?

Which states and territories is it found?

NT, QLD

What areas within states and territories is it found?

Scattered populations of Laurel Clock Vine are found in the Cairns area of northern Queensland and in south-eastern Queensland (CRC 2003). It has not been recorded for the Northern Territory in their checklist of plants (Cowie & Kerrigan 2007) although it is known as an ornamental in Darwin (Smith 1995). It also occurs on the Daly River, southwest of Darwin (CRC 2003).

Where does it originate?

Laurel Clock Vine is native to India, Myanmar and Malaysia, but has been cultivated throughout the tropics for its ornamental flowers (CRC 2003; Barker 1986).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

QLD

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

YES

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 laurifolia

Other scientific names (synonyms)?

• Thunbergia grandiflora var. laurifolia (Lindl.) Benoist
• Thunbergia harrisii Hook.

Does it have other known common name(s)?

Thunbergia, Laurel-leaved Thunbergia, Purple Allamanda