Jacaranda.
Family Bignoniaceae > Tribe Jacarandeae.
Jacaranda mimosifolia, one of the about 50 species, is the most commonly grown.
It is naturalised in north eastern Australia and has become invasive in some areas.
It is uncertain if it is the same as J. acutifolia.
Jacarandas are long lived, deciduous trees up to 20 to 30 m high.
Smooth grey-brown bark becomes scaly on older trees.
Twigs are slightly zig-zag.
Oppositely arranged leaves, up to 30 or 40 cm long, are twice divided – bipinnate.
The first divisions are up to 10 cm long and the second division are 10 to 15 mm long.
In late Winter the leaves turn yellow before thay fall.
New leaves form after the flowers appear in Spring or early Summer.
The branched, terminal inflorescences, with masses of flowers are up to 30 cm long.
The bisexual flowers are up to 5 cm long with 5 sepals and 5 petals.
The green or purple calyx, and the corolla are tubular or bell-shaped with 5 terminal lobes.
The corolla tube is curved and somewhat flattened.
The blue to mauve flowers are bilabiate (2 lips).
The upper lip has 2 lobes and the lower lip, of 3 lobes has some hairs.
Jacaranda cuspida has a prominent white throat on the upper lip.
There are 4 stamens in 2 unequal pairs that are inserted onto the corolla tube.
The anthers of those in each pair lie close together.
There is an infertile staminode that is longer than the fertile stamens.
It has glandular hairs on part of the filament and on the aborted anthers.
The superior ovary, of 2 fused carpels has one style with a bi-lobed stigma.
It is surrounded by a nectiferous disc.
The fruit are flat, round or oval capsules 5 to 7 cm wide.
They split into 2 sections to release the flat winged seeds.
Other species have deep mauve, lilac, or very pale purple flowers.
Grafted trees with pure white flowers are available.
There are also dwarf plants and some with variegated leaves.
J.F.
