Parkinsonia aculeata Parkinsonia Tree shape - shrub or small tree up to 10 metres high, usually 2-8 metres: Flowers - fragrant, five-petalled, predominantly yellow with orange spots on one petal which can turn completely orange. Each flower grows on a long, slender, drooping stalk: Pods/Seeds - straight, straw-coloured pods, 5−10 cm long, no hairs, constricted between the seeds. Seeds are oval and hard: Leaves - long, flattened leaf stalk with tiny oblong leaflets spaced along each side. 7-12mm spines growing from the leaf nodes: Bark - smooth and green, straw coloured and lightly textured at base of older trees: Branch shape - slightly zigzagged ![enter image description here]( "Parkinsonia_Boulia_AWhite cropped.jpg") **Weed status** Parkinsonia is a serious rangeland weed widespread through Western Australia, the Northern Territory, and Queensland. Native to the Americas, it is declared in all Australian states and territories and is recognised as a [Weed of National Significance]( (WoNS). **Impact** Parkinsonia can form dense thickets in riparian habitats and floodplains. Thickets negatively affect both the environment and the pastoral industry in rangeland Australia by outcompeting native trees and shrubs and impacting the growth of native grasses. Thickets make mustering difficult, impede access to water, provide refuge for feral animals such as pigs, damage soil structure and contribute to soil erosion. Parkinsonia is adapted to a wide range of soil types and it is predicted that it will continue to spread through water courses and adjoining areas throughout the semi-arid and tropical rangelands of northern Australia. Parkinsonia is commonly referred to as a prickle bush due to the sharp spines growing from the leaf nodes and may be confused with other prickle bushes such as mesquite (*Prosopis* spp), prickly acacia (*Acacia nilotica*), mimosa (*Mimosa pigra*), and mimosa bush (*Acacia farnesiana*) (see the [Parkinsonia National Case Study Manual]( for further information). **Biological control** Three insects were introduced between 1989 and 1995 to control parkinsonia; a sap‐sucking bug *Rhinacloa callicrates*, and two seed‐feeding beetles *Mimosetes ulkei* and *Penthobruchus germaini*. These were inadequate on their own to control parkinsonia populations. Further research led to the introduction of two additional biological control agents: UU1 – *Eueupithecia cisplatensis* UU2 – *Eueupithecia vollonoides* *Eueupithecia cisplatensis* and *E. vollonoides* are leaf-feeding geometrid moths from Argentina. The morphology and behaviour of both species are very similar although UU1, in general, is slightly smaller than UU2. Larvae feed on the leaflets and leaf stalks of parkinsonia. If larval densities are high enough, particularly on juvenile plants, this feeding can substantially defoliate the plant and reduce photosynthesis, Repeated damage can impact plant health, reduce growth and seed production, and make the plant more susceptible to diseases such as the soil-borne pathogen associated with dieback. ![enter image description here]( "Eueupithecia_UU_Kelli Pukalis cropped.jpg") Unless otherwise indicated, all images are Copyright CSIRO. For additional information, please see: