Parkinsonia aculeata

Parkinsonia aculeata is a tree from the family Fabaceae; it may also commonly be called parkinsonia, Jerusalem thorn, Mexican palo verde, or jellybean tree. P.aculeata is natively distributed in Mexico, northern South America, the Caribbean and in the southern United States. It is a major weed in Australia.

P. aculeata grows from 2 - 8 metres high. The leaves and stems are hairless. The flattened leaf stalk is edged by two rows of tiny oval leaflets. The branches grow sharp spines 7 - 12 mm long. Flowers are yellow and fragrant, 20 mm in diameter, growing from a long slender stalk in groups of eight to ten. The seed pods are leathery in appearance and are light brown in colour when mature.

Parkinsonia in Australia

P. aculeata is a major weed in Australia. It was introduced as an ornamental and shade tree around 1900. It is now widespread through Western Australia, the Northern Territory and Queensland covering about 800 000 hectares of land, and has the potential to spread through most of the semi-arid to subhumid tropical area in Australia.

P. aculeata forms dense thickets, preventing access for humans, native animals and livestock to waterways. P. aculeata seed pods float and the plant spreads by dropping pods into water, or pods are washed dowstream by seasonal flooding.

Several control methods are used to reduce the existing population and the spread of P. aculeata in Australia. Three insects have been introduced to Australia for the biological control of parkinsonia: the parkinsonia seed beetles, Penthobruchus germaini and Mimosetes ulkei, both have larvae that specifically eat the seeds from parkinsonia pods and are proving to be a useful management tool, and the parkinsonia leaf bug, Rhinacloa callicrates, which destroys photosynthetic tissues but has had no impact on the weed. Fire is effective for young trees; mechanical removal and herbicides are also used.

References

• Cooperative Centre for Weed Management. Weed of the month - Parkinsonia aculeata, April 2005
• QLD Dept of Natural Resources and Mines, Land Protection. 2004. NRM facts pest series: Parkinsonia