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Black locust flowers

Black locust leaves, thorns & pods

Honey locust branched thorns

Honey locust leaves & pods



Subfamily Mimosoidae (wattles) within Fabaceae (peas)


Mesquite (Prosopis species) are listed as noxious in in category 2 (a notifiable weed: the local control authority (local council) must be informed if you see this weed, and it must be eradicated and the land must be kept free of the weed) in Southern Slopes and Upper Lachlan LCAs within the Southern Tablelands and South East Region, and most other inland LCAs. It is illegal to sell, propagate or knowingly distribute mesquite species anywhere in NSW. Mesquite is also listed as a Weed of National Significance.


Mesquite species are straggling shrubs or small trees to 10 metres high with distinctive zigzag stems. Leaves are bipinnate, similar to those of some wattles. Flowers are yellow and wattle-like, in short spikes in the leaf axils. The pods are cylindrical and bean-like, constricted between the individual seeds. The thorns at the base of each leaf are a distinctive feature of mesquite, but may not always be present. Single thorns 20-60mm long are found in Prosopis glandulosa and paired spines 4-40mm long may occur on P. velutina and P. pallida.  The photo illustrates Prosopis juliflora (provided by Forest & Kim Starr, USGS, Hawaii).

View the fact sheet on this weed at the link below.

Preferred habitat and impacts

Mesquite has naturalised from garden and soil stabilisation plantings in the arid inland, including western NSW, and has invaded arid pasture land, particularly along watercourses. It has proven very hard to eradicate.

It greatly reduces carrying capacity, restricts access to water, and the long thorns are a menace to livestock and can puncture car tyres.


There are four mesquite species and various hybrids which have previously been sold as garden plants, so they could escape into new areas of infestation from garden or farm plantings. Livestock eat the seeds and spread them to other areas in their droppings. The germination of the seeds is enhanced after passing through the gut. The pods and seeds also float in water. Existing plants may spread vegetatively by suckering from the roots and layering at the branch tips if these come into contact with moist soil.


There is a slight similarity, in being thorny trees, with the related black locust (Robinia pseudoacacia) and honey locust (Gleditsia triacanthos), also in the pea family. Both these weedy trees sucker from the roots to form thickets and spread by the same means as mesquite. However their leaflets are larger and flowers are not wattle-like yellow balls.


Do not plant mesquite and if you see it being offered for sale anywhere, inform your local Council weeds staff. If you have trees of these species planted it would be advisable to remove them. Cutting the tree down and painting the stump with glyphosate would probably be the most efficient way to do this, although follow-up cutting and painting may be needed to deal with regrowth suckers arising from the root system.

Mesquite Mesquite 529.4 KB