Raunkiær system

The Raunkiær system is a system for categorizing plants using life-form categories, devised by Danish botanist Christen C. Raunkiær and later extended by various authors.

It was first proposed in a talk to the Danish Botanical Society in 1904 as can be inferred from the printed discussion of that talk, but not the talk itself, nor its title. The journal, Botanisk Tidsskrift, published brief comments on the talk by M.P. Porsild, with replies by Raunkiaer. A fuller account appeared in French the following year. Raunkiær elaborated further on the system and published this in Danish in 1907.

The original note and the 1907 paper were much later translated to English and published with Raunkiær's collected works.

Raunkiær's life-form scheme has subsequently been revised and modified by various authors, but the main structure has survived.

The subdivisions of the Raunkiær system are based on the place of the plant's growth-point (bud) during seasons with adverse conditions (cold seasons and dry seasons):

Projecting stems into the air – normally woody perennials - with resting buds more than 25 cm above soil level, e.g. trees and shrubs, but also epiphytes, which Raunkiær separated out as a special group in later versions of the system.

Raunkiaer further subdivided the phanerophytes according to height as megaphanerophytes, mesophanerophytes, microphanerophytes, and nanophanerophytes. Other characters used to further subdivide were duration of leaves (evergreen or deciduous) and presence of covering bracts on buds (eight classes in all). Three further classes, phanerophytic stem succulents, phanerophytic epiphytes, and phanerophytic herbs brought the number of subclasses to 12.

Buds on persistent shoots near the ground – woody plants with perennating buds borne close to the ground, no more than 25 cm above the soil surface, (e.g., bilberry and periwinkle).

...
Wikipedia