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Alternanthera bettzickiana (Regel) G. Nicholson 1884
pronounced: al-ter-NANTH-ur-uh bet-zik-ee-AH-nuh
(Amaranthaceae – the amaranth family)
common name: Red Calico Plant
This genus consists of approximately 80 species, and is a widespread genus with cosmopolitan distribution. Several species are aquatic in habit, but most of them are spreading plants like Alternanthis bettzickiana.
A very well-known species is Alternanthera philoxeroides, commonly called Alligator weed, a South American native that has spread into many countries and has become a noxious weed in many parts of the world. It forms dense sprawling mats, reaching up to as much as 15 m across, that choke ponds, lakes, streams, canals and irrigation channels. It is found in every state and territory of Australia, and is regarded as one of the worst weeds in the country because of its invasiveness, potential for spread, and economic and environmental impacts. It invades both land and water, and is very difficult to control. It can grow either with its roots embedded in the banks, or in the bottom of shallow ponds and streams, or it can float freely on the surface of the water, with its roots trailing and taking their nourishment from the water. Its long, spreading stems are hollow, and this helps it to float. Attempts are being made to control it biologically, with the alligator weed flea beetle Agasicles hygrophila, the alligator weed thrips Amynothrips andersoni , and the alligator weed stem borer Arcola malloi, as mechanical and chemical controls give only temporary control. It infests most of the Townsville waterways, but I have seen none on the island – which doesn’t mean there isn’t any!
Alternanthera bettzickiana, however, is a very common plant on the island, both where it is used in gardens as an edging border, and also in the many places where it has escaped into the wild. It is remarkably pest-resistant, which probably accounts for its spread. It is a perennial herb, usually between 20 and 50 cm tall. Originating in Brazil, it is found with stems either erect or creeping, much-branched, with the apical part of the stem quadrangular, and the basal part cylindrical, and hairy at the apex and nodes. Although it will grow in semi-aquatic situations, it is not the nuisance that its close relative, alligator weed, is.
The petioles are very short (1 – 4 mm) and slightly hairy, the leaf blades green or red or various shades of purple, or sometimes tinged red or yellow. The shape of the leaves varies from oblong to oblong-ovate or spatulate, and they are usually 1 – 6 cm long; hairy when young.
The white inflorescences are found in the leaf axils, often on long stalks.
Photographs taken at Picnic Bay 2009, 2010
Page last updated 12th July 2018