laurel clock vine

Thunbergia laurifolia
Vine
Opposite
Simple
White
Purple
Blue
Green

A long-lived vine, with tuberous roots, that grows up to 15 m in height. Its younger stems are square in cross-section and bear oppositely arranged leaves on stalks up to 6 cm long. Its leaves are variable in shape but their margins are usually entire or only slightly toothed. Its blue, violet or purple trumpet-shaped flowers (3.5-4.5 cm long and 6-8 cm across) have a pale yellow or whitish coloured throat. Each flower is borne on a short stalk (about 2 cm long) and has two leafy bracts (20-50 mm long) at its base. Its fruiting capsules, when present, are rounded with a tapered beak (up to 3 cm long).

Common names 
Also known as: laurel clock vine, babbler's bill, thunbergia, babbler's vine, blue thunbergia, blue trumpet vine, purple allamanda, sky flower ,
Family 
Acanthaceae
Deciduous 
No
Flowering time 
Spring - Summer
Native/Exotic 
Exotic
Origin 
Native to southern China, Taiwan and south-eastern Asia (i.e. Myanmar and Malaysia).
Notifiable 
Yes
State declaration 
Class 1
Council declaration 
Class E - Early detection and eradication
Known distribution 

This species is not yet widely distributed in Australia. Scattered populations are found in the coastal districts of northern Queensland and it has also been recorded in south-eastern Queensland. Also naturalised on several Pacific islands (i.e. French Polynesia, Fiji, the Solomon Islands, Western Samoa and Hawaii).

Habitat 

A potential weed of watercourses (i.e. riparian areas), disturbed forests, forest margins, open woodlands, roadsides, fence-lines, gardens and plantation crops in tropical and sub-tropical regions.

Habit 

A long-lived (i.e. perennial) vine that may grow as a groundcover or climb over vegetation up to a height of 15 m.

Stem and leaves 

Younger stems are square in cross-section (i.e. quadrangular). Older stems are quite thick when mature and usually become rounded. The oppositely arranged leaves are borne on stalks (i.e. petioles) up to 6 cm long (usually less than 3 cm long). These leaves are broadly oval (i.e. elliptic) to narrowly egg-shaped in outline (i.e. ovate-lanceolate) with broad (i.e. obtuse) or slightly heart-shaped (i.e. sub-cordate) bases (7-18 cm long and 2.5-8 cm wide). Their margins are usually entire, but sometimes they are slightly toothed (i.e. crenated). These leaves are hairless (i.e. glabrous) and their tips usually come to a point (i.e. they have an acute or acuminate apex).

Flowers and fruits 

The trumpet-shaped (i.e. tubular) flowers are borne in elongated clusters (i.e. racemes) on short drooping (i.e. pendent) branches. They are large and showy (35-45 mm long and 6-8 cm across) with five blue, violet or purple petal lobes and a pale yellow or whitish coloured throat. Each flower is borne on a short stalk (i.e. pedicel) about 2 cm long and has two leafy bracts (i.e. bracteoles) at its base. These bracts (20-50 mm long and 15-20 mm long) are oblong in shape and have pointed tips (i.e. acuminate apices). The sepals are fused together and reduced to a ring-like structure (i.e. calyx tube) and the leafy bracts may be streaked with purple or red. Flowering occurs throughout the year, but is most abundant during summer and autumn. The fruit is a capsule with an oval (i.e. ellipsoid) base (about 14 mm long and 14 mm wide) and a long tapered beak (1-3 cm long and 4-6 mm wide). These fruit are only produced in the warmer parts of northern Australia.

Reproduction and dispersal 

This species reproduces via seeds and is also capable of regenerating from stem fragments or portions of its tuberous roots.It has been widely cultivated as a garden plant (i.e. ornamental), and is most commonly dispersed in dumped garden waste. The tuberous roots may also be spread during soil moving activities (e.g. roadworks) and by flood waters.