Jacaranda

Jacaranda mimosifolia syn Jacaranda mimosaefolia
Tree
Alternate
Compound
Purple
Green

Deciduous or evergreen tree, 5-15 m tall. Its main distinguishing feature is its spectacular lavender blue blooms which has led to its popularity as an ornamental tree. Jacaranda mimosifolia is fast growing and resprouts easily if damaged.

Common names 
Also known as: black poui, blue jacaranda, Brazilian rose wood, fern tree, green ebony, jacaranda tree,
Family 
Bignoniaceae
Deciduous 
Yes
Flowering time 
Late Spring
Native/Exotic 
Exotic
Origin 
Native to South America
Notifiable 
No
State declaration 
Nil
Council declaration 
SIL – Special Investigation List
Known distribution 

Locations within which Jacaranda mimosifolia is naturalised include the warmer parts of eastern Australia, southern Africa, Hawaii, south-eastern USA and outside its native range in southern South America.

Habitat 

J. mimosifolia is native to areas having a temperate mesothermal climate with a marked dry season. In tropical regions it grows best in highland areas up to 2400 m with an annual rainfall of 900-1300 mm, but will also tolerate rainfall up to 2000 mm. It does not tolerate frost. This species grows well on well-drained sandy loam soils, although it will survive on poorer shallow soils. The species does not tolerate waterlogged or clay soils. 

Habit 

The tree grows to a height of up to 20 m (66 ft).[3] Its bark is thin and grey-brown in colour, smooth when the tree is young though it eventually becomes finely scaly. The twigs are slender and slightly zigzag; they are a light reddish-brown in colour. 

Impact and control methods 

Jacaranda mimosifolia is regarded as an invasive species in parts of South Africa and Queensland, Australia, where it can out-compete native species. It can form thickets of seedlings beneath planted trees from which the species may expand and exclude other vegetation.

Jacaranda (Jacaranda mimosifolia) is regarded as an environmental weed in New South Wales and Queensland. Though this species has been widely and commonly cultivated throughout Australia for many years, it was first recorded as becoming naturalised in Queensland in 1987. It has spread from cultivation into nearby open woodlands and grasslands, particularly on creekbanks and near waterways.

Jacaranda (Jacaranda mimosifolia) was recently ranked among the top 200 most important environmental weeds in south-eastern Queensland. It appears on numerous local environmental weed lists in this region (e.g. in Ipswich City, Redland Shire and Caboolture Shire) and has been recorded in eucalypt forest on the Gold Coast.

This species is also widely regarded as an environmental weed in north-eastern New South Wales (e.g. in the Byron, Lismore and Tweed Shires) and is also seen as a potential environmental weed in the wider Sydney and Blue Mountains region. Though it rarely reaches maturity in these cooler areas, naturalised plants have been reported in grasslands and woodlands in suburban Sydney.

Jacaranda mimosifolia is very difficult to control once established. Large trees must be ring-barked or cut down below ground level and any regrowth treated with herbicide. . When using any herbicide always read the label first and follow all instructions and safety requirements. If in doubt consult an expert.

Stem and leaves 

Leaves: bright green, feathery and fern-like. Individual leaves are narrow and elliptic, 3 – 12 mm long and arranged either side of a 5 – 10 cm long stem. They turn yellow in autumn before falling from the tree.

Flowers and fruits 

Flowers striking blue-violet, in clusters, each flower bell shaped, to 4 cm, usually on the bare tree before leaf growth.Fruit a rounded woody capsule to 7 cm across with a wavy edge, brownblack when mature, splitting on the tree to set free many light-winged seeds. Capsules may hang on the tree for up to 2 years.

Reproduction and dispersal 

J. mimosifolia depends on a range of insects for pollination, including bees of medium or large size. Pods dry on the tree and split after about a year, releasing the light seeds. Each with its own feathery, circular wing, appears to make the seeds best suited for wind dispersal. However, it is likely that seeds, individually or still encased in whole pods, can also be transported by water.The optimum temperature for germination is 25°C. Seeds remain viable for at least 12 months in they remain dry. 

Dehiscent pods and light seeds 

Similar species 

Based on foliage, young plants of J. mimosifolia could be confused with a variety of other species. However, the characteristic flowers mean that mature trees cannot be mistaken and even after flowering, the round, flat pods make the tree stand out. The similarity of foliage and form and use as a common ornamental street tree means that J. mimosifolia and Delonix regia can sometimes be confused when there are no flowers or fruit. However, both are highly distinct, with mauve-blue-violet flows and round pods in J. mimosifolia compared to red-yellow flowers are long pods (often 50 cm or more) in D. regia.