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The life-form of the mature
plant is classified according to the system of Raunkiaer (1934), as modified
by Govaerts et al. (2000). Broadly speaking, the approach classifies
plants according to the positions of their perennating buds (hence the
level of protection that buds are given), during seasons that are unfavourable
for growth. A summary of the classification is provided below, and
abbreviations used in SID are given in parentheses.
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Phanerophytes (phan.)
have stems that are woody and persistent, and buds that are normally exposed
3 m or more above ground level. This category includes trees and large
shrubs
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Nanophanerophytes (nanophan.)
also have woody, persistent stems, but are lower in stature with buds typically
located between 0.5 m and 3 m above ground level. This category includes
smaller shrubs.
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Herbaceous phanerophytes
(herb. phan.)
have herbaceous stems that persist for several years and include tropical
species such as bananas and plantains.
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Chamaephytes (cham.) can
have stems that are herbaceous or woody and persistent, and have
buds that are located above soil level, but never by more than 50 cm. This
group includes dwarf shrubs and some perennial herbs.
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Hemicryptophytes (hemicr.)
have
herbaceous stems that often die-back during unfavourable seasons, and surviving
buds placed on (or just below) soil level. This group includes many biennial
and perennial herbs, including those in which buds grow from a basal rosette.
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Geophytes (not abbreviated)
have stems that die back during unfavourable seasons, with the plant surviving
as a bulb, rhizome, tuber or root bud.
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Therophytes (ther.) complete
their entire life-cycle during the favourable season, and survive the unfavourable
season as a seed. This group includes all annual herbs.
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Epiphytes (epi.) grow
on other plants (their growing buds occur on another plant).
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Helophytes (hel.) are
plants in which surviving buds are buried in water-saturated soil, or below
water-level, but that have flowers and leaves that are fully emergent during
the growing season. The group includes many marsh and emergent aquatic
herbs.
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Hydrophytes (hydro.)
are fully aquatic herbs in which surviving buds are submerged, or buried
in soil beneath water. Their stems and vegetative shoots grow entirely
underwater and leaves can be submerged or floating, but only the flower-bearing
parts may be emergent.
The above categories may be
preceded by the following terms:
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cl. denotes a climbing
plant.
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succ. denotes a plant
having succulent stems.
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par. denotes a plant
that is parasitic.
References cited:
Govaerts, R., Frodin, D.G.
and Radcliffe-Smith, A. 2000. World Checklist and Bibliography of Euphorbiaceae
(with Pandanaceae). Volume 1. The Royal Botanic Gardens, Kew.
Raunkiaer, C. 1934. The Life
Forms of Plants and Statistical Plant Geography. The Clarendon Press, Oxford.
©
Copyright (2008), Board of Trustees of the Royal Botanic Gardens, Kew
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