Definition: a plant that is free-floating on the water surface, not attached to or penetrating the substrate, with some photosynthetic parts in contact with air.
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.