Jacaranda chelonia Griseb.

Jacaranda mimosifolia is a deciduous tree up to 20 m in height with spreading branches making a light crown. Bark pale brown and furrowed, transverse cracks dividing the ridges between the furrows into long, narrow scales. The bole almost always short and malformed, and up to 40-50 cm in diameter. Leaves compound and feathery on a stalk to 40 cm; up to 30 pairs of pinnae bearing small, pointed leaflets. 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, brown-black when mature, splitting on the tree to set free many light-winged seeds. Capsules may hang on the tree for up to 2 years. The generic name is a latinized form of an aboriginal name used in Brazil.

In Puerto Rico, flowering is from early spring to June, the fruit maturing in spring and early summer. In northern India, the tree flowers from March to April. Ninety-nine per cent of flowers open in the early hours of the morning between 5 and 7 a.m. The tree seeds annually beginning at 8-10 years old.

Grows best on well-drained sandy loam soils, although it will also survive on poor shallow soils. It does not tolerate waterlogged or clay soils.

J. mimosifolia prefers highland areas but can also grow in some drier ones. It is frost tender when young. A deep-rooted, greedy feeder so that few plants or crops can grow below it; therefore, best planted away from flowerbeds. Leaf fall is also considerable.

Jacaranda is native to Brazil and Argentina but has been introduced as an ornamental in most parts of the tropics, though in many tropical climates its flowering is light, irregular and disappointing. It was introduced to Kenya in 1907 to the Nairobi Arboretum and is now an outstanding ornamental tree of the city and district, where it flowers when leafless.

Jacaranda can be raised from either seed or cuttings, the latter being more usual. The tree is a prolific seeder; no pretreatment is required; germination rate is 50-92%. Seeds should be sown fresh for best germination results; fresh seed soaked in water for 24 hours take 10-12 days for germination, which continues for 2 months. Planting should be from container stock during cool weather; 8-10 months should elapse before plants can be transplanted to the field. In avenues, planting may be done at 2 x 2 m or 3 x 3 m in well-manured 30-cubic cm pits. The plants can be raised from branch cuttings.

The plants need weeding for about the 1st 2 years. Young trees should be staked until well rooted. They require regular watering. Very fast growing on good sites; up to 3 m/yr in height in the first 2 years and over 1 m/yr over the first 9 years. Established plants respond well to coppicing. If used as an ornamental roadside tree, wide spacing (over 5 m) is advisable. It is a light demander, and to flower prolifically it needs to be grown in the open.

Orthodox seed storage behaviour; viability is maintained for at least 12 months in open storage at room temperature. Seeds tolerate desiccation to moisture content in equilibrium with 15% rh at 25 deg. C, no loss in viability in subsequent storage in liquid nitrogen at -20 deg. C. There are about 59 000 seeds/kg.

Shade or shelter: The tree creates pleasant open shade and can be used effectively as a screen or as a windbreak. Ornamental: J. mimosifolia is widely grown throughout the highland tropics. When trees are not in flower, the finely cut foliage is also attractive, especially at close range.

Apiculture: The relatively large flowers easily attract bees; therefore, it is suitable for bee forage. Fuel: J. mimosifolia provides useful firewood. Timber: The timber is yellowish-white, hard, moderately heavy, fine textured, easy to work, and is used for carpentry. Wood is light brown and soft; it is used for poles and for making small items such as tool handles and carvings. Note that the wood associated with the timber trade name ‘jacaranda’ does not come from this tree but from Dalbergia nigra. Medicine: Bark and roots are used for syphilis. Leaves also used as a vulnerary.