定义：A depression caused by erosion by water or ice. Low-lying land bordered by higher ground; especially elongate, relatively large gently sloping depressions of the Earth's surface, commonly situated between two mountains or between ranges of hills or mountains, and often containing a stream with an outlet.
定义：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.
定义：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.
定义：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)
定义：The institution that holds a type specimen for a given species. The recommended best practice is to use the identifier in a collections registry such as the Biodiversity Collections Index (http://www.biodiversitycollectionsindex.org/).
