Raunkiær plant life-form
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The Raunkiær system is a system for categorizing plants using life-form categories, devised by Danish
botanist Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...
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 ''Botanisk Tidsskrift'' (standard abbreviation ''Bot. Tidsskr.'') was a Danish mixed scientific and amateur journal concerning botany, issued in Copenhagen by the Danish Botanical Society. It was published from 1866 to 1980, when it fused with Bo ...
, published brief comments on the talk by M.P. Porsild, with replies by Raunkiær. A fuller account appeared in
French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...
the following year. Raunkiær elaborated further on the system and published this in Danish in 1907.Ch. 2 in Raunkiær (1934): The life-forms of plants and their bearings on geography, p. 2-104. The original note and the 1907 paper were much later translated to
English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ...
and published with Raunkiær's collected works.Ch. 1 in Raunkiær (1934): Biological types with reference to the adaption of plants to survive the unfavourable season, p. 1.


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
perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also widel ...
s, grow stems into the air, with their resting buds being more than 50 cm above the soil surface, e.g.
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
s and
shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from tree ...
s, and also epiphytes, which Raunkiær later separated as a distinct class (see below). Raunkiær further divided the phanerophytes according to height as *Megaphanerophytes, *Mesophanerophytes, *Microphanerophytes, and *Nanophanerophytes. Further division was premised on the characters of duration of foliage, i. e. evergreen or deciduous, and presence of covering
bracts In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or ...
on buds, for 8 classes. 3 further divisions were made to increase the total of classes to 12: *Phanerophytic stem succulents, *Phanerophytic epiphytes, and *Phanerophytic herbs.


Epiphytes

Epiphyte An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phoroph ...
s were originally included in the phanerophytes (see above) but then separated because they do not grow in soil, so the soil location is irrelevant in classifying them.


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 Bilberries (), or sometimes European blueberries, are a primarily Eurasian species of low-growing shrubs in the genus '' Vaccinium'' (family Ericaceae), bearing edible, dark blue berries. The species most often referred to is ''Vaccinium myrti ...
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

These plants have subterranean or under water resting buds, and are divided into: *Geophytes: rest in dry soil as a
rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow ...
,
bulb In botany, a bulb is structurally a short stem with fleshy leaves or leaf basesBell, A.D. 1997. ''Plant form: an illustrated guide to flowering plant morphology''. Oxford University Press, Oxford, U.K. that function as food storage organs dur ...
,
corm A corm, bulbo-tuber, or bulbotuber is a short, vertical, swollen underground plant stem that serves as a storage organ that some plants use to survive winter or other adverse conditions such as summer drought and heat (perennation). The word ' ...
, et cetera, e.g.
crocus ''Crocus'' (; plural: crocuses or croci) is a genus of seasonal flowering plants in the family Iridaceae (iris family) comprising about 100 species of perennials growing from corms. They are low growing plants, whose flower stems remain under ...
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 ''Caltha palustris'', known as marsh-marigold and kingcup, is a small to medium size perennial herbaceous plant of the buttercup family, native to marshes, fens, ditches and wet woodland in temperate regions of the Northern Hemisphere. It ...
; and *Hydrophytes: rest submerged under water, e.g. water lily and frogbit.


Therophytes

These are annual plants that complete their lives rapidly in favorable conditions and survive the unfavorable cold or dry season in the form of seeds. Many desert plants are by necessity therophytes.


Aerophytes

Aerophytes were a later addition to the system. These are plants that obtain moisture and nutrients from the air and rain. They usually grow on other plants yet are not parasitic on them. These are
perennial plant A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
s whose roots
atrophy Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply ...
. Some can live on mobile
sand dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...
s. Like epiphytes and hemicryptophytes, their buds are near the soil surface. Some '' Tillandsia'' species are classified as aerophytes.


Popular References

Farley Mowat, in his book,
Never Cry Wolf ''Never Cry Wolf'' is an account of the author's experience observing wolves in subarctic Canada by Farley Mowat, first published in 1963 by McClelland and Stewart. It was adapted into a film of the same name in 1983. It has been credited for dra ...
, described using a Raunkiær's Circle in making a “cover degree” study to determine the ratios of various plants one to the other. He spoke of it as "a device designed in hell."


References

{{DEFAULTSORT:Raunkier plant life-form Plant life-forms Botanical nomenclature Ecology de:Lebensform (Botanik)