TWO-HORNED SEA ROCKET

(Cakile maritima)

(Photos: E. Cousins, Cape Jervis)

This member of the mustard family is a sprawling, succulent annual, up to half a metre tall. It grows in clumps in the sand along seashores, such as Morgans Beach. Leaves are fleshy, shiny, green and deeply lobed. The 4-petalled pale purple flowers appear year round. They open from the bottom of the stalk, with fruits sometimes appearing at the bottom of that stalk simultaneously. The ‘rocket’ in the common name doesn’t come from the plant being edible like salad greens, but from the shape of its corky brown fruits … they are swollen, both with or without horns, near the base, making a ‘rocket’ shape!

AFRICAN DAISY

(Arctotis stoechadifolia)

(Photos: partially opened flower, mat formed by plant; E. Cousins, Cape Jervis)

The silvery foliage and daisy-like flower would make this an attractive ornamental in a garden … if it would just stay there! Another garden escapee, this weed is found on the coastal reserve at Cape Jervis, but it certainly isn’t restricted to there. It is a major problem in other S.A. reserves, such as the Hallett Cove and Scott Creek Conservation Parks. You’ll recognize it by its woolly stems, heavily lobed leaves, and daisy-like flowers which vary in colour from white through pink and purple. In sand dunes, it can grow into dense mats (see photo). These mats cause local plants to be lost through shading, smothering and competition for resources. Apparently, this weed can also cause the structure of sand dunes to alter, e.g. by becoming steeper in slope.

BROAD-LEAF COTTON BUSH

(Gomphocarpus cancellatus)

(Photos: plant, monarch butterfly and caterpillar; flower bud; E. Cousins; Cape Jervis)

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. The plant seed is spread by wind and water; its sap can be an 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, which have been plentiful around Cape Jervis this year. 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!

STINKWORT

(Dittrichia graveolens)

(Photos: C.Schultz; Cape Jervis)

This annual is native to the Mediterranean region, but adapts to other temperate climes with a winter rainfall of 300-800mm. It likes open (unshaded), disturbed sites where there is sparse groundcover: roadsides, paddocks, wasteland and riverbanks; it also spreads into dry grasslands. If undetected or ignored, it can take over. The plant is aromatic, with an odour like camphor (hence the common name). In summer it grows rapidly from a rosette to an erect plant up to 50cm, with sticky, slightly hairy grey-green foliage. Hundreds of small yellow flowers appear from January to April, and fruits from February. These fruits produce massive numbers of seeds (about 15,000 per plant!), which are viable for 3 years. The 2mm seeds are hairy, with about 30 bristles each. These hairs allow them to cling to clothing, machinery, animal fur, etc., and hence enable seed dispersal by means other than wind and water. The plant can cause dermatitis, itchiness and blistering of your skin, so avoid touching it. Grazing animals are even worse off … ingested seeds can give them enteritis and kidney disease!