Alternanthera philoxeroides

Cultivation Details

Alternanthera philoxeroides is found in tropical to warm temperate zones. Plants are not very cold tolerant - frost and ice will kill exposed stems and leaves, but stems underneath this top mat of dead material are often protected enough to survive the winter and become the basis of the next season's growth^[1]. Succeeds on a wide range of substrata, from sand to heavy clay. When floating on water, it may be rooted in the bank or substrate, or can be free floating^[1]. The plant grows best in aquatic sites but may establish as a terrestrial species in wet and poor pastures and on irrigated lands. It prefers level areas of shore or shallow water where it is protected from wave erosion. As with many weeds it thrives in eutrophic conditions and thus often increases where urban and industrial development have polluted and degraded water quality. It loves fresh water of high fertility, but can also tolerate saline soils and waters and is found along the inland tidal reaches of rivers that run to the sea^[2]. This species is a serious problem in waterways in tropical and warm-temperate regions of the world, where it probably grows in a wider range of water and soil conditions than any other major aquatic weed. Its growth is equally startling whether free floating, loosely attached and forming a mat, or as an emersed plant in a wet or relatively dry field^[2]. Its dense mat of growth can smother most other herbaceous plant species. The plant often does not produce viable seed, but manages to spread freely by vegetative means^[1]. For example, severe storms may strip the leaves from anchored mats or tear the tangled vegetation loose and move it to a new location where it can then grow and establish itself. In the same way, attempts at physical control usually only serve to spread the weed since it is very difficult to ensure that no fragments of the plant are left^[2].