Copy of `Radford University - Glossary of Biogeography`

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Radford University - Glossary of Biogeography
Category: Sciences > Biogeography
Date & country: 11/09/2007, USA
Words: 117


Rosette
a growthform in which the leaves are arranged in concentric circles or whorls around a central bud.

Saprophyte
a plant lacking chlorophyll that obtains its nutrients from dead organic matter. The bacteria and fungi of decay are examples, but there are also flowering plants like the white Indian pipes of eastern US Temperate Broadleaf Deciduous Forests or the giant Rafflesia of the Indo-Malyasian formation of the Tropical Braodleaf Evergreen Forest that are saprophytes.

Sedge
any member of the Cyperacaeae, a family of flowering plants that in their growthform resemble grasses.

Speciation
the process by which new species arise. The process by which discontinuities between populations occur due to the development of mechanisms creating the reproductive isolation of one population from the other. Allopatric speciation: species formation that occurs during geographic isolation of populations. Generally believed to be the most common way in which new species arise, especially among the higher animals. Sympatric speciation: the formation of new species without geographic isolation; the acquisition of reproductively isolating mechanism among individuals coexisting in the same area. Not infrequent in plants.

Species
groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups. The lowest taxonomic rank and presumably only real taxonomic unit in nature.

Strangler
a plant that begins life as an epiphyte in the canopy of a forest and sends its roots down the trunk of a host tree and into the substrate. The roots may form a thick woody net around the host's trunk, but it is apparently the foliage of the strangler that eventually kills the host by blocking sunlight from the latter's leaves. A type of growthform found in tropical forests.

Structure
the physical arrangement or spatial patterns of the components of an ecosystem, especially the plant life. Includes growthforms, number of canopy layers, degree of cover, distribution patterns of species within the ecosystem (patches, for example). Structure may also refer to the organization of the ecosystem in terms of trophic levels.

Subspecies
a geographically defined aggregate of local populations which differ phenotypically from other such subdivisions of a species in other geographic areas.

Succulent
a plant that is able to store water in its tissues and then withdraw it during times of drought. Water storage tissue may be found in the stem, leaves, or roots depending on the species. Stem succlulents, leaf succulents, and root succulents are types of growthforms.

Sympatric
literally, 'same country'; refers to distribution areas of different species that overlap.

Taxon
any one of the levels in the taxonomic hierarchy:

Taxonomy
the science of classifying and identifying organisms. The modern classification of organisms reflects their presumed phylogeny.

Tussock
a hummock of grasses or sedges bound together by their roots

Vicariant
Refers to species that occupy similar ecological niches but in geographic isolation from each other. Implies a phylogenetic relationship existing between the two species.

Weed
a species that volunteers in artificially modified habitats and is considered undesirable by people. The same species may occur elsewhere in a wild state, or even in cultivation.

Weedy habit
refers to the propensity of certain species to disperse easily and widely and to colonize disturbed habitats.

Xerophyte
a plant well adapted to withstand prolonged drought. The typical xerophyte is a deciduous shrub with tiny leaves and a shallow root system that etends well beyond the crown of the shrub.