Synusia (plural Synusiae) is a term in plant ecology that refers to a layer of vegetation consisting of species with shared life forms. It has been compared with guilds in zoology.
The term synusia was introduced by Helmut Gams in 1918[1] although similar ideas were proposed using terms such as "Genossenschaften" (brotherhoods) and "Schicht" (society).[2] [3] They have been defined as ecological groups of plants that share similarities in their life-form, share the same niche and play a similar role. They can be taxonomically different but have similar habitats.