Plant life-form schemes constitute a way of classifying plants alternatively to the ordinary species-genus-family
scientific classification. In colloquial speech, plants may be classified as
trees,
shrubs,
herbs (
forbs and
graminoids), etc. The scientific use of life-form schemes emphasizes plant function in the
ecosystem and that the same function or "adaptedness" to the environment may be achieved in a number of ways, i.e. plant species that are closely related
phylogenetically may have widely different life-form, for example
Adoxa and
Sambucus are from the same family, but the former is a small
herbaceous plant and the latter is a
shrub or
tree. Conversely, unrelated species may share a life-form through
convergent evolution. The most widely applied life-form scheme is the
Raunkiær system.