Sicklebush

Dichrostachys cinerea
Tree
Alternate
Compound
Yellow
Pink
Green

The bark is rough, yellow to grey-brown and frequently fissured and the stem is rarely thicker than 230 mm. The flowers are 25 to 50 mm long, pendulous spikes that are borne in the leaf axils, singly or in bundles. The pleasant-smelling fluffy flowers are lilac in the upper half and yellow in the lower, giving rise to the descriptive name Chinese lantern tree in other countries. Its flowering season is spring, generally from September to February.

Common names 
Also known as: Sickle bush,
Family 
Mimosaceae
Deciduous 
No
Flowering time 
Its flowering season is spring, generally from September to February.
Native/Exotic 
Exotic
Origin 
Africa
Notifiable 
No
State declaration 
Nil
Council declaration 
Class E - Early detection and eradication
Known distribution 

Sicklebush has a wide natural distribution ranging from southern and tropical Africa to India, although the true native range is not easy to determine as the literature sources contradict one another as to whether the species is an exotic which has naturalized or a native species in particular countries. For example, the species is thought to be native to the Northern Territory, Australia, however Cowan (1998) suggests that it naturalized there.  It is widespread in the Sudan zone and southern Sahel of Africa where it forms dense hammocks, in the Kalahari and Transvaal of southern Africa and in East Africa to Somalia and Yemen (von Maydell, 1986). 

Habitat 

D. cinerea is found in a variety of habitats, and is widely distributed in the seasonally dry tropics of Africa, Asia and Australia. In India, D. cinerea occurs in dry deciduous forests, in Sengal and Sudan it occurs on lateritic soils, in Malaysia in areas with strong seasonal climates and in Australia it is known to grow on poor soils.

D. cinerea can grow on a range of soil types including saline and infertile soils. Mean annual temperatures where D. cinerea grows are 15-27°C, but also tolerating mean monthly temperatures as high as 38°C and an absolute minimum temperature of 0°C. Mean annual rainfall ranges are 200-1400 mm, with dry season durations of 4-10 months. It is known to occur from sea level in coastal areas up to 2000 m altitude in Ethiopia.

Habit 

D. cinerea is a highly variable thorny shrub or small tree to 8 m tall though often smaller. 

Impact and control methods 

D. cinerea is a fast growing tree that has become an undesirable weed and is particularly a problem in areas where there has been overgrazing. In the areas were it invades the species form very dense thickets making areas impenetrable. The species can regenerate from the smallest amount of root or through its root suckers. The seeds can survive for long periods of time in the soil as well as being able to withstand moderate frost. In Cuba, the use of mechanical control methods has been successful in reducing the area covered by D. cinerea, however, it is still a major problem in the country. As of yet there are no biocontrol agents being used although potential agents have been identified. Mechanical and chemical control are currently the most efficient control measures.

Stem and leaves 

The bark is rough, yellow to grey-brown and frequently fissured and the stem is rarely thicker than 230 mm. The twice-compound, petiolate leaves are very variable in size with 4 to 19 pairs of pinnae and each pinna with 9 to 41 pairs of leaflets, giving it an Acacia-like appearance. The petioles (leaf stalks) are up to 50 mm long and the leaf length varies between 10 and 160 mm. The young twigs are slightly hairy and a characteristic feature is that the spines are not modified stipules but hardened branchlets, ending in a straight, sharp point.

Flowers and fruits 

D. cinerea is characterized by the bicoloured inflorescence that is pink in the upper part and yellow in the lower part. The upper flowers are sterile with protruding staminodes and the lower flowers are hermaphroditic with 1 pistil and 10 yellow stamens each. Inflorescence spicate, solitary on a bracteate, short shoot, 6-9 cm long including the glabrous to puberulous peduncle. The pods are dark-brown and twisted in form in clusters, narrowly oblong, variously curved and/or coiled, 5-7 cm long, 8-15 mm wide, blackish, glabrous. Seeds biconvex, elliptic to subcircular, 4 mm long, 2-4 mm wide, pale tan, glossy; pleurogram elliptic

Reproduction and dispersal 

Large numbers of seeds are produced almost all year long