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Prosopis
(Mesquite)
Travelers to the north of the continent might mistake this prolific plant for a native, maybe even a wattle.
From its humble beginnings in Australia as an ornamental and fodder tree, the various mesquite species now form impenetrable thorny thickets that have devastated agricultural land and natural habitats.
Its distribution and spread across the top end, and its potential to move further south, has earned it a place in the Weeds of National Significance List.
The photogaph here (by Colin G Wilson) shows the flower spike and the fern-like leaves of mesquite.
The tree is actually made up of various mesquite species and hybrids, so it varies from multi-stemmed shrubby bushes to single stemmed trees with a spreading canopy, growing from 3 to 15 metres tall.
One of the reasons it has got out of control in Australia (aside from liking the hot northern weather) is its ability to grow a 20 metre tap root.
Its other great abilities are to reproduce prolifically and be a relatively long lived species. In the wild that’s about thirty years but a specimen in the Brisbane Botanic Gardens is 105 years old.
The tree produces seeds pods (shown here in detail in a photograph by Nathan March). These and the foliage are palatable to animals. The pods are an excellent food source and the digestion by animals assists in the germination of the seeds. Hundreds of thousands of seeds can be produced on a single mature plant.
CONTROL
Burning, mechanical removal by ploughing, grubbing and chaining etc, and herbicide application to cut stumps are the common methods used to control mesquite.
Several biological control agents have been trialed, including a leaf sucking bug, seed-seeding beetles and a leaf-tying moth. The moth has established itself at most of the release sites and is having an impact, but the others haven’t been particularly successful.
WHAT HOME GARDENERS CAN DO
One of the strategies in stopping further spread of this plant is to strictly enforce quarantine to ensure no further introductions of weedy Prosopis species. Be aware that many different mesquite species are responsible for the infestation, so don’t be tempted to bring in seed from overseas just because you think it might be a ‘safe’ species or variety.
Source: www.deh.gov.au/biodiversity/invasive/publications/pubs/proposis.pdf
Click here to return to the invasive plants list.
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