Parkinsonia aculeata

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Parkinsonia aculeata

Flowers, leaves and pods

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Fabales
Family:	Fabaceae
Subfamily:	Caesalpinioideae
Tribe:	Caesalpinieae
Genus:	Parkinsonia
Species:	P. aculeata

Binomial name

Parkinsonia aculeata
L.

Parkinsonia aculeata is a tree from the family Fabaceae; common names include Mexican Palo Verde, Parkinsonia, Jerusalem thorn, or Jellybean tree. It is native to the southwestern United States (western Texas, southern Arizona), Mexico, the Caribbean, South America south to northern Argentina, and the Galapagos Islands.

It grows from 2 to 8 meters high. The leaves and stems are hairless. The flattened leaf stalk is edged by two rows of 25-30 tiny oval leaflets; the leaflets are soon deciduous in dry weather, leaving the green leaf stalks and branches to photosynthesize. The branches grow sharp spines 7-12 mm long. The flowers are yellow and fragrant, 20 mm in diameter, growing from a long slender stalk in groups of eight to ten. The fruit is a pod, leathery in appearance, light brown when mature.

[edit] Invasive problems

P. aculeata is a major invasive species in Australia, parts of tropical Africa, Hawaii, and other islands in the Pacific Ocean.

It was introduced to Australia as an ornamental tree and for shade around 1900. It is now a serious weed widespread through Western Australia, the Northern Territory and Queensland, covering about 8,000 square kilometres of land, and has the potential to spread through most of the semi-arid to subhumid tropical area in Australia.

It forms dense thickets, preventing access for humans, native animals and livestock to waterways. The 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 biological control; 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.