Definition: forests which are inundated with freshwater, either permanently or seasonally. They normally occur along the lower reaches of rivers and around freshwater lakes
Definition: veins run parallel and equidistant to each other for most of the length of the leaf; they may converge or fuse (anastomose) towards the apex
Definition: The important feature of homospory is the four fold division involved in spore production, this takes the form of either a tetrahedra which gives a trilete (Y shaped scar) spore or a tetragon which gives a monolete (single linear scar) spore.