pronounced: gom-FREE-nuh se-loh-see-OY-deez
The only derivation I have been able to find for Gomphrena refers to an ancient classical name for an amaranth. This sounds likely, but I have not been able to verify it. Celosioides means ‘resembling the Celosia genus’; κηλος (kelos) is Greek, burnt, dry.
This is a prostrate or sprawling annual herb from South America that grows in disturbed ground, roadsides, lawns and cultivated areas throughout the tropics and subtropics, up to about 25 cm in height. It has a thick, fleshy taproot, which enables it to survive quite well during dry periods, although it is at its best during the wet season. The stems are striate and hairy, with some older stems glabrous. Its leaves are opposite, simple, petiolate or subsessile, the petiole 2 – 10 mm long. The leaf blade is 2 – 6 cm long, sometimes a little more, and up to 2 cm wide, elliptic or ovate or obovate, the base tapering, the margins entire, the apex usually acuminate. The blade is hairy: ciliate; mainly glabrous above; silky hairy below.
The flowers are in spikes in a dense globose or ovoid or cylindrical head, usually 1 – 2 cm across, with white bracts and bracteoles. They are predominantly white or pale green, somewhat irregular, sessile between 2 leaves. The calyx is 5 – 8 mm long; there are 5 sepals, all free, and densely woolly outside for ¾ of their length. There are 5 stamens, opposite the sepals. coherent to each other, the filaments closely joined for most of their length into a 5-toothed staminal tube. The ovary is superior, and single-celled.
The fruit is an indehiscent thin-walled, non-fleshy and tiny (less than 2 mm) capsule, with a single seed. Galahs are particularly fond of these seeds, and flocks of the birds are often seen harvesting them.
The plant is said to be poisonous to horses if they eat large quantities for a long time. When grazing on areas containing large amounts of the species, they develop a form of staggers.
In Ghana, where malaria causes many deaths every year, Gomphrena Weed is one of the several plants prescribed by herbalists for the treatment of the disease.
The ‘real’ khaki weed, Alternanthera pungens, another South American native, is a very different kettle of fish. It is a sprawling plant, flat on the ground, and looks rather like Gomphrena Weed; but it has very sharp burrs, which, when mature, attach to animals, motor vehicle tyres, the pads on dogs’ feet, and to the feet of humans who like walking around without shoes. That included me when I was a boy growing up in Townsville, and my feet suffered accordingly. This weed also causes, it is claimed, skin problems in cattle, and hay fever, asthma and dermatitis in some people.