Laurel clock vine (Thunbergia grandiflora)
Also known as:
blue sky vine
Laurel clock vine is a woody, twining vine with clusters of pale blue to purplish flowers. It smothers and kills other plants.
Profile
How does this weed affect you?
Laurel clock vine is an ornamental plant that has escaped gardens and invades natural areas. It:
- climbs over and smothers native plants
- shades out understorey plants
- can cause mature trees to fall due to the weight of the vine
- competes with pasture plants
- invades cane fields
- can form impenetrable infestations.
What does it look like?
Laurel clock vine is a woody, twining, perennial vine that climbs up to 15 m high.
Leaves are:
- bright green when young and dark green when older but paler on the underside
- up to 22 cm long and 15 cm wide
- variable in shape and may be oval, heart-shaped, triangular or angularly lobed
- pointed at the tip
- rough on the surface
- smooth, toothed or lobed along the edges
- prominently veined with 3 or 5 veins from the base
- on stalks up to 10 cm long
- opposite along the stem.
Flowers are:
- trumpet-shaped with 5 rounded lobes (one longer than the others)
- pale blue, violet, mauve with a pale yellow or whitish throat and white on the outer side
- up to 8 cm long and 6–8 cm wide
- in clusters on long, drooping branches
- present all year but most common in summer and autumn.
Fruit are:
- a brown capsule containing 2–4 seeds
- 3 cm long
- oval-shaped with a long, pointed beak.
Stems are:
- robust
- drooping at the top of the plant.
Roots are:
- tuberous (up to 70 kg)
- extensive.
Similar looking plants
Laurel clock vine looks similar to some introduced morning glory vines including:
- Common morning glory (Ipomoea purpurea), which has deep violet-blue flowers with stripes along the petals.
- Coastal morning glory (Ipomoea cairica), which has shorter leaves (up to 9 cm) with 5-7 deep lobes.
- Purple morning glory (Ipomoea indica), which has smaller leaves (2-10 cm) and the flowers are not in large clusters, usually just 1-3 together.
All of these Ipomoea weeds have alternate rather than opposite leaves.
Scientific name change
This plant was previously named Thunbergia laurifolia.
Where is it found?
Laurel clock vine has been found in a few locations on the North Coast and in the Greater Sydney region. It was previously sold as a garden plant.
It is native to India, Bhutan, Nepal, southern China and Myanmar.
What type of environment does it grow in?
Laurel clock vine grows in tropical, subtropical and warm temperate regions. It grows best in frost-free areas with fertile, acidic, well-drained soil. Plants have been found:
- along riverbanks
- in forests, including rainforests, especially along the margins and disturbed areas
- in open woodlands
- on roadsides
- along fence-lines.
How does it spread?
By seed
Laurel clock vine produces some seeds especially in warmer regions. The seeds are spread several meters from the plant when the capsules burst open.
By plant parts
Most spread is from plant parts. Plants can grow from tubers and fragments of stems. These can be spread by:
- people dumping garden waste
- movement of contaminated soil
- floodwaters.
References
Cooperative Research Centre for Australian Weed Management (2003). Weed Management Guide: Laurel clock vine (Thunbergia laurifolia). CRC Weed Management.
Harden, G., McDonald, W. & Williams, J. (2007). Rainforest climbing plants: A field guide to their identification. Gwen Harden Publishing. Nambucca Head NSW.
Identic Pty Ltd. and Lucid Central (2016). Environmental Weeds of Australia Fact sheet: Thunbergia grandiflora (Roxb. ex Rottler) Roxb. Retrieved 2023 from https://keyserver.lucidcentral.org/weeds/data/media/Html/thunbergia_grandiflora.htm
Parsons, W.T., & Cuthbertson, E. G. (2001). Noxious weeds of Australia. CSIRO publishing.
More information
Control
Successful weed control relies on follow up after the initial efforts. This means looking for and killing regrowth or new seedlings. Using a combination of control methods is usually more successful.
Physical removal
By hand
Dig out small plants. Remove the tubers and all of the roots. Be very careful when disposing of plants to make sure that it does not regrow from broken roots or stems.
Cutting vines at ground level will help smothered plants survive but laurel clock vine will regrow from tubers. Follow-up control will be required.
Disposal
Contact your local council for advice on disposing of this weed.
Chemical control
Spot spraying
Apply to actively growing plants. Thoroughly cover all of the foliage. This method is unsuitable for vines that have climbed high or are covering desirable plants.
Basal barking
Apply herbicide mixed with diesel all the way around the base of each stem from ground level to a height of at least 30 cm from the ground. Wet the bark to the point of runoff. Apply with a paint brush or a pressure sprayer.
Splatter gun
Splatter-guns use small amounts of concentrated herbicide. They spray large droplets that limit spray drift. This method is suitable for very dense infestations of weeds that are difficult to reach.
Cut stump method
Cut stems, and apply herbicide to the stump within 15 seconds of cutting.
Weed wipers
Wipers or wands apply herbicide directly onto leaves. This method can better target the chemical and minimise damage to other species.
Herbicide options
WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au
See Using herbicides for more information.
PERMIT 9907 Expires 31/03/2025
Fluroxypyr 200 g/L
(Various products)
Rate: 500 mL to 1 L per 100 L water
Comments: Spot spray
Withholding period: Do not graze failed crops and treated pastures or cut for stock feed for 7 days after application. See label for further information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Fluroxypyr 200 g/L
(Various products)
Rate: 35 mL per L diesel/kerosene
Comments: Basal bark
Withholding period: Do not graze failed crops and treated pastures or cut for stock feed for 7 days after application. See label for further information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Fluroxypyr 333 g/L
(Starane™ Advanced)
Rate: 300 to 600 mL per 100 L water
Comments: Spot spray
Withholding period: Do not graze failed crops and treated pastures or cut for stock food for 7 days after application. See label for more information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Fluroxypyr 333 g/L
(Starane™ Advanced)
Rate: 21 mL per L diesel/kerosene
Comments: Basal bark
Withholding period: Do not graze failed crops and treated pastures or cut for stock food for 7 days after application. See label for more information.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L
(Various products)
Rate: One part product to 50 parts water
Comments: Spot spray
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L
(Various products)
Rate: One part product to 1.5 parts water
Comments: Cut scrape and paint
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L
(Various products)
Rate: One part product to 9 parts water
Comments: Splatter gun
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L
(Various products)
Rate: One part product to 20 parts water
Comments: Wipe onto leaves
Withholding period: Nil.
Herbicide group: 9 (previously group M), Inhibition of 5-enolpyruvyl shikimate-3 phosphate synthase (EPSP inhibition)
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Metsulfuron-methyl 600 g/kg
(Various products)
Rate: 10 - 20 g per 100 L water plus surfactant
Comments: Spot spray
Withholding period: Nil (recommended not to graze for 7 days before treatment and for 7 days after treatment to allow adequate chemical uptake in target weeds).
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors)
Resistance risk: High
PERMIT 9907 Expires 31/03/2025
Metsulfuron-methyl 600 g/kg
(Various products)
Rate: 10 g per 1 L of water plus surfactant
Comments: Wipe onto leaves
Withholding period: Nil (recommended not to graze for 7 days before treatment and for 7 days after treatment to allow adequate chemical uptake in target weeds).
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors)
Resistance risk: High
Biosecurity duty
The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.
| Area | Duty |
|---|---|
| All of NSW | General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable. |
For technical advice and assistance with identification please contact your local council weeds officer.
Reviewed 2023
