Definition: A shallow stretch of a river or stream, where the current is above the average stream velocity and where the water forms small rippled waves as a result. It often consists of a rocky bed of gravels or other small stones.
Definition: This organism produces this material or substance, either during its life or after death. A produces B if some process that occurs in A has output B.
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.
Definition: A group of species that exploit the same food resources, and/or use the same feeding or foraging methods. http://en.wikipedia.org/wiki/Guild_(ecology)
