ABSTRACT
Growth and morphology are dependent on habitat and environmental conditions. Alligator weed is commonly described as an amphibious plant due to its ability to root at the water’s edge and grow across the surface, which is aided by thick hollow stems for floatation and thin fibrous roots that extract nutrients from the water column (Julien et al, 1992). This process creates thick mats that can grow up to 70m from the shoreline (Julien et al, 1992), and can become detached and float to new locations (Zeigler, 1967). It is moderately tolerant of salinity, which it achieves through increasing leaf thickness (Longstreth et al, 1984), and which allows it to grow in estuarine habitats (Julien et al, 1992). Alligator weed also grows in moist terrestrial habitats as a prostrate plant with thin stems and thick roots that contain extensive stores of carbohydrate (Wilson et al, 2007). Root material builds up over time to create large reserves in the soil; over 7.3kg m−2 dry biomass has been collected at terrestrial sites in Australia with a greater than 20 year invasion history (Schooler et al, 2008). Observations of aboveground biomass are not indicative of below-ground biomass, with established sites having ten times more biomass below ground than above (Schooler et al, 2008).
