All the casuarinas are nitrogen fixing. Casuarinas support an actinorhiza symbiont in their root nodules, as opposed to the rhizobium symbiont found in the root nodules of leguminous trees that fix N 2 . C. equisetifolia has two variants. C. equisetifolia var.
Casuarinas are actually typical angiosperms with simplified and reduced unisexual flowers.
They are dioecious or monoecious, the proportion of male, female and monoecious trees varying widely from one site to another. The leaves are reduced to white or brown scales fused laterally at the base in whorls that define nodes on the branchlets. Individual plants have striking phenotypic variations in the crown shape, branch angle, length of branchlets, and size and shape of cones. C. equisetifolia is known to hybridize with other casuarinas, such as C. junghuhniana and C. glauca . Ecology Casuarina equisetifolia is intolerant of frost.