Raunkiær plant life-form
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.
History
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 Raunkiær. 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 in 1934 with Raunkiær's collected works.
Modernization
Raunkiær's life-form scheme has subsequently been revised and modified by various authors, but the main structure has survived. Raunkiær's life-form system may be useful in researching the transformations of biotas and the genesis of some groups of phytophagous animals.Subdivisions
The subdivisions of the Raunkiær system are premised on the location of the bud of a plant during seasons with adverse conditions, i. e. cold seasons and dry seasons:Phanerophytes
These plants, normally woody perennials, grow stems into the air, with their resting buds being more than 50 cm above the soil surface, e.g. trees and shrubs, and also [|epiphytes], which Raunkiær later separated as a distinct class.Raunkiær further divided the phanerophytes according to height as
- Megaphanerophytes,
- Mesophanerophytes,
- Microphanerophytes, and
- Nanophanerophytes.
- Phanerophytic stem succulents,
- Phanerophytic epiphytes, and
- Phanerophytic herbs.
Epiphytes
Chamaephytes
These plants have buds on persistent shoots near the soil surface; woody plants with perennating buds borne close to the soil surface, a maximum of 25 cm above the soil surface, e.g., bilberry and periwinkle.Hemicryptophytes
These plants have buds at or near the soil surface, e.g. common daisy and dandelion, and are divided into:- Protohemicryptophytes: only cauline foliage;
- Partial rosette plants: both cauline and basal rosette foliage; and
- Rosette plants: only basal rosette foliage.
Cryptophytes
- Geophytes: rest in dry soil as a rhizome, bulb, corm, et cetera, e.g. crocus and tulip, and are subdivided into:
- *Rhizome geophytes,
- *Stem-tuber geophytes,
- *Root-tuber geophytes,
- *Bulb geophytes, and
- *Root geophytes.
- Helophytes: rest in marshy or wet soil, e.g. reedmace and marsh-marigold; and
- Hydrophytes: rest submerged under water, e.g. water lily and frogbit.
Therophytes