His pupil, Theophrastus, in Historia Plantarum (c. 350 BC), was the first who formally recognized plant habits: trees, shrubs and herbs.
[3] Some earlier authors (e.g., Humboldt, 1806) did classify species according to physiognomy,[4][5][6] but were explicit about the entities being merely practical classes without any relation to plant function.
[8][9] Warming's first attempt in life-form classification was his work Om Skudbygning, Overvintring og Foryngelse (translated title "On shoot architecture, perennation and rejuvenation" - See line drawings) (1884).
The term life-form was first coined by Warming ("livsform") in his 1895 book Plantesamfund,[8] but was translated to "growthform" in the 1909 English version Oecology of Plants.
However, due to high age and illness, he was able to publish a draft of his last system only[11] Following Warming's line of emphasizing functional characters, Oscar Drude devised a life-form scheme in his Die Systematische und Geographische Anordnung der Phanerogamen (1887).
[12] Christen C. Raunkiær's classification (1904) recognized life-forms (first called "biological types") on the basis of plant adaptation to survive the unfavorable season, be it cold or dry, that is the position of buds with respect to the soil surface.
Du Rietz [de] (1931) reviewed the previous life-form schemes in 1931 and strongly criticized the attempt to include "epharmonic" characters, i.e., those that can change in response to the environment (see phenotypic plasticity).