Weed of the Month-June 2018


(Gomphocarpus cancellatus)

This woody weed from South Africa grows to about 1 metre high, and competes with natives for space, nutrients and water. It has escaped cultivation as an ornamental, and has invaded many reserves and national parks. We never worried about this weed too much on our reserve at Cape Jervis in the past, but it has definitely become more widespread. So lately we have been more active in removing it. The plant seed is spread by wind and water; its sap can be irritating or toxic to some people, so use gloves when dealing with infestations. Hand pull small plants; use cut-and-swab or drill-and-fill techniques to poison large ones. If infestations are kept under control, the cotton bush does bring one benefit. Over the winter, you’ll notice the plant has many white-purple flowers…and often plenty of caterpillars, devouring the soft leaves and stems. These are the larvae of the Monarch butterfly. The Monarch is not truly an Australian native (though a resident for hundreds of years!), but apparently the larvae of the Lesser Monarch, which IS an Australian native butterfly, also uses this bush as a food source!