Appendix II – Glossary of Terms

alluvial
characterized by the deposition of sediment by a stream or other running water at any point along its course.

alpine
the zone on mountain tops between permanent snow and the cold limits of trees.

annual
plant species that complete their life-cycles within a single growing season.

annual vegetation
associations that persist for less than one year, or are dominated by annual species.

biennial
plant species that complete their life-cycles within two growing seasons.

boreal
northern biogeographical region typically referring to subpolar and cold temperate areas.

brackish
tidal water with a salinity of 0.5-30 parts per thousand.

broad-leaved
describes a plant with leaves that have well-defined leaf blades and are relatively wide in outline (shape) as opposed to needle-like or linear; leaf area is typically greater than 500 square millimeters or 1 square inch.

bryophyte
nonvascular, terrestrial green plant, including mosses, hornworts, and liverworts.

bunch grass
multi-stemmed (caespitose) life form of grasses characterized by clumps of erect shoots that slowly spread horizontally by tillers, generally creating distinct individual plants spaced across the ground; often applied to sedges and other graminoids with similar life forms.

caespitose
(cespitose) describes a low branching pattern from near the base that forms a multi-stemmed or a bunched appearance.

cliff
any high, very steep to perpendicular, or overhanging face of a rock outcrop.

cloud forest
tropical and subtropical montane forest characterized by a high incidence of low-level cloud cover, usually at the canopy level, promoting development of an abundance of vascular epiphytes.

cold-deciduous
describes a plant that sheds its leaves as a strategy to avoid seasonal periods of low temperature, often initiated by photoperiod; applied to vegetation adapted to seasonal cold season influences (temperate).

conical-crowned
describes a needle-leaved evergreen tree with a pyramidal or cone-shaped canopy or life form; for example, Douglas fir and silver fir (Pseudotsuga menziesii and Abies amabilis).

creeping
describes the pattern of stems growing at or just beneath the surface of the ground and usually producing roots at nodes.

crustose lichen
lichen life form that grows in intimate contact with its substrate, lacks a lower cortex and rhizoids (root-like structures), and is impossible to separate from the substrate without destroying the thallus; lichen with an unlobed, flattened thallus, growing adnate to the substrate.

cushion plant
a low, woody, plant life form so densely branched that it forms a compact canopy that is pad- or bolster-like in appearance; usually with microphyllous foliage; characteristic of alpine and tundra plants.

cylindrical-crowned
describes a needle-leaved evergreen tree with a narrow, essentially cylinder-shaped canopy or life form; for example, subalpine fir and black spruce (Abies lasiocarpa and Picea mariana).

deciduous
describes a woody plant that seasonally loses all of its leaves and becomes temporarily bare-stemmed.

deciduous vegetation
associations in which deciduous woody plants generally contribute 75 percent or more to total dominant plant cover.

dominant
an organism, group of organisms, or taxon that by its size, abundance, or coverage exerts considerable influence upon an association's biotic (such as structure and function) and abiotic (such as shade and relative humidity) conditions.

drought-deciduous
describes a plant that sheds its leaves as a strategy to avoid seasonal periods of high transpiration demand; applied to vegetation adapted to climates with seasonal drought and little cold-season influence (tropical-subtropical).

dwarf-shrub
low-growing shrub life form usually under 0.5 meters or 1.5 feet tall (never exceeding 1 meter or 3 feet tall) at maturity.

dwarf-shrubland
vegetation dominated by low-growing shrubs and/or trees, usually under 0.5 meters or 1.5 feet tall; dwarf-shrubs generally form greater than 25 percent cover, although (rarely) may be less, and tree and taller shrubs generally form less than 25 percent cover.

ephemeral forb vegetation
annual associations or synusiae that, during favorable periods, dominate areas which are usually sparsely vegetated or unvegetated for most of the year.

epiphyte
vascular plant that grows by germinating and rooting on other plants or other perched structures; sometimes called "air plants."

episodic forb vegetation
herbaceous-dominated associations that occupy areas periodically denuded of vegetation.

ericoid
plants of the Heath Family or Family Eriaceae; for example, heaths, rhododendrons, and blueberries (Erica, Rhododendron, and Vaccinium).

evergreen
describes a plant that has green leaves all year round; or a plant that in xeric habitats has green stems or trunks and never produces leaves.

evergreen vegetation
associations in which evergreen woody plants generally contribute 75 percent or more to total dominant plant cover; vegetation canopy is never without photosynthetic tissue.

extremely xeromorphic
associations that are adapted primarily to growing in drought-persistent environments, and are only secondarily adapted to other environmental stresses; plants typically have several well-developed xeromorphic characteristics.

facultatively deciduous
describes evergreen species that shed leaves only under extreme conditions; this strategy is often associated with plants found in semiarid saline/alkaline environments; for example, Atriplex-Kochia saltbush in Australia and North America.

foliose lichen
lichen life form that is leafy in appearance and loosely attached to its substrate; lichen with a lobed, flattened thallus growing loosely attached to the substrate, the lobes flattened or inflated with distinctly differentiated upper and lower surfaces; umbilicate lichens are included.

forb
a broad-leaved herbaceous plant.

forest
vegetation dominated by trees with their crowns overlapping, generally forming 60 - 100 percent cover; includes reproductive stages or immature secondary growth stands that are temporarily less than 5 meters or 16.5 feet tall.

fresh water
water with a salinity of less than 0.5 parts per thousand.

fruticose lichen
lichen life form that is bunched, shrubby or "hairy" in appearance and loosely attached to its substrate; lichen with the thallus branched, the branches solid, or hollow and round, or flattened without distinctly differentiated upper and lower surfaces; squamulose lichens are included.

giant
describes mature forests in which the height of a typical canopy exceeds 50 meters or 165 feet.

graminoid
grasses, and grass-like plants including sedges and rushes.

grassland
vegetation dominated by perennial graminoid plants.

growth form
the shape or appearance of a plant.

hemi-sclerophyllous
describes a plant with stiff, firm, leathery leaves that partially retain their rigidity during wilting; for example, rhododendron and salal (Rhododendron and Gaultheria).

herb
a vascular plant without significant woody tissue above or at the ground; an annual, biennial, or perennial plant lacking significant thickening by secondary woody growth, with perennating buds borne at or below the ground surface (hemicryophytes, geophytes, helophytes, and therophytes of Raunkier).

herbaceous vegetation
vegetation in which herbs (mostly graminoids, forbs, and ferns) form at least 25 percent cover, and woody vegetation has generally less than 25 percent cover; herbaceous cover may be less than 25 percent in cases where the cover of each of the other life forms present is less than 25 percent and herbaceous cover exceeds the cover of the other life forms.

hygromorphous herbs
herbaceous plants structurally adapted for life in water-dominated or aquatic habitats.

intermittently flooded
substrate is usually exposed, but surface water can be present for variable periods without detectable seasonal periodicity. Inundation is not seasonally predictable and is dependent upon highly localized rain storms. This modifier was developed for use in the arid West for water regimes of Playa lakes, intermittent streams, and dry washes but can be used elsewhere when appropriate. This modifier can be applied to both wetland and non-wetland situations. Equivalent to Cowardin's Intermittently Flooded modifier.

irregularly exposed
land surface is exposed by tides less often than daily; the area from mean low tide to extreme low spring tide. Equivalent to Cowardin's Irregularly Exposed.

irregularly flooded
tidal water floods land surface less often than daily. The area must be flooded by tides at least once yearly as a result of extreme high spring tide plus wind plus flow. The area extends from mean high water inland to the maximum extent of tide plus the splash zone. Equivalent to Cowardin's Irregularly Flooded except in tidal Riverine, Lacustrine, and Palustrine areas where if an area is only irregularly flooded by fresh tidal waters, the appropriate non-tidal modifier, e.g., Temporarily Flooded, Seasonally Flooded, Semipermanently Flooded, will apply.

krummholz
growth form assumed by tree species at the upper treeline or in the alpine zone; characterized by a creeping and multi-stemmed growth pattern due to desiccation and physical damage caused by wind and blowing ice crystals near the upper treeline; the same species grows as an erect, single-stemmed tree at lower elevation.

lichen
an organism generally recognized as a single plant that consists of a fungus and an alga or cyanobacterium living in symbiotic association.

lignified
describes a plant with woody tissue developed by secondary cell wall thickening by lignin and cellulose.

life form
the shape or appearance of a plant that mostly reflects inherited or genetic influences.

low forb
a broad-leaved herbaceous plant usually less than 1 meter or 3 feet tall when inflorescences are fully developed.

lowland
a large land area with vegetation reflecting limits set by regional climate and soil/site conditions; an area where elevation is not the primary gradient affecting vegetation zonation.

matted
describes a creeping plant that by reiterative growth has overlapping stems and forms a low, dense ground cover.

medium-tall grassland
graminoid-dominated vegetation usually between 0.5 to 1 meter or 1.5 to 3 feet tall when inflorescences are fully developed in temperate zones, and to 2 meters or 6 feet in tropical zones.

microphyllous
describes a plant with small leaves; individual leaf surface areas are less than 500 square millimeters or one square inch.

mixed evergreen-deciduous
describes vegetation in which evergreen and deciduous species each generally contribute 25-75 percent to the total canopy cover.

montane
describes the zone in mountainous regions where the influence of altitude (vertical relief) results in local climatic regimes that are sufficiently different from those in the adjacent lowlands as to cause a complex vertical climate-vegetation-soil zonation; includes vegetation at the base of a mountain when it is different from lowland vegetation.

natural/semi-natural
describes vegetation that has not been planted or treated with an annual management or manipulation regime.

needle-leaved
describes a plant with slender, elongated leaves; for example, pine and fir trees (Pinus and Abies).

nonvascular plant
a plant without specialized water or fluid conductive tissue (xylem and phloem); includes bryophytes, lichens, and algae.

nonvascular vegetation
vegetation that is dominated by bryophytes and lichens, generally forming at least 25 percent cover, with other vegetation forming less than 25 percent cover; nonvascular cover may be less than 25 percent in cases where the cover of each of the other life forms present is less than 25 percent and nonvascular cover exceeds the cover of other life forms.

pavement
a relatively flat surface of consolidated material, generally exposed bedrock.

perennial
plant species with a life-cycle that characteristically lasts more than two growing seasons and persists for several years.

perennial herbaceous vegetation
associations that persist for several years and are dominated by herbaceous species.

planted/cultivated
describes vegetation planted by humans and/or treated with annual management; usually dominated by plants not indigenous to the area.

polar
geographically, the areas within the Arctic and Antarctic circles in which the sun is entirely not visible for six months, and is constantly above the horizon for the next six months; climatically, polar regions are characterized by the lack of a period of warmth and by enduring cold; in polar climates the average temperature of each month is below 10º C (50º F).

pulvinate mosses
mosses growing in cushion-like mats or clumps.

rainforest
vegetation in frost-free areas dominated by trees that are always wet from rain.

regularly flooded
tidal water alternately floods and exposes the land surface daily, from mean low (lower low on West Coast) to mean high (higher high on West Coast). Equivalent to Cowardin's Regularly Flooded.

revolute
rolled toward the lower surface of a leaf.

rosulate
a plant with leaves arranged in rosettes (circular clusters).

rounded-crowned
describes a needle-leaved evergreen tree with a basically semi-circular canopy or life form; for example, whitebark pine and alligator juniper (Pinus albicaulis and Juniperus deppeana).

saltwater
water with a salinity of greater than 30 parts per thousand.

saturated
surface water is seldom present, but substrate is saturated to surface for extended periods during the growing season. Equivalent to Cowardin's Saturated modifier.

scale-leaved
describes a plant with small, overlapping leaves that usually lie flat on the stem; for example, eastern red-cedar and western red-cedar (Juniperus virginiana and Thuja plicata).

sclerophyllous
describes a plant with usually evergreen leaves that are stiff and firm and retain their stiffness even when wilted; they are common in, but not restricted to, regions with a long summer drought and predictable yet limited winter rain.

scree
a sheet of coarse rock debris covering a mountain slope without an adjacent cliff.

scrub
vegetation dominated by shrubs, including thickets.

seasonal
showing periodicity related to the seasons; applied to vegetation exhibiting pronounced seasonal periodicity marked by conspicuous physiognomic changes.

seasonal evergreen vegetation
associations in which most of the upper canopy plants retain leaves year-round and drop some leaves during unfavorable seasons.

seasonally flooded
surface water is present for extended periods during the growing season, but is absent by the end of the growing season in most years. The water table after flooding ceases is very variable, extending from saturated to a water table well below the ground surface. Includes Cowardin's Seasonal, Seasonal-Saturated, and Seasonal-Well Drained modifiers.

semi-arid
a climatic region having an annual precipitation, usually between 25.4 and 50.8 centimeters (10-20 inches) per year, this being greater than a truly arid climate; typically, the vegetation is composed of grasses with or without woody plant layers.

semi-deciduous vegetation
associations (usually tropical and subtropical) in which most of the upper canopy trees are drought-deciduous and many of the understory trees and shrubs are evergreen. The evergreen and deciduous woody plants are not always separated by layers.

semi-evergreen vegetation
associations in which evergreen and deciduous species each generally contribute 25-75 percent of total tree cover; specifically, this term refers to tropical and subtropical vegetation in which most of the upper canopy trees are evergreen mixed with drought-deciduous trees.

semipermanently flooded
surface water persists throughout growing season in most years except during periods of drought. Land surface is normally saturated when water level drops below soil surface. Includes Cowardin's Intermittently Exposed and Semipermanently Flooded modifiers.

short grassland
graminoid-dominated vegetation usually less than 0.5 meters or 1.5 feet tall when inflorescences are fully developed.

shrub
perennial woody species with a life form that is usually less than 4 to 5 meters or 13 to 16 feet in height; typically, plants have several stems arising from or near the ground, but this term includes short tuft-tree, bamboo, and woody vine species; length of vine may exceed 5 meters; shrub species growth form may be taller than 5 meters or single-stemmed under certain environmental conditions.

shrubland
(scrub) vegetation dominated by shrubs greater than 0.5 meters or 1.5 feet and typically less than 4 to 5 meters or 13 to 16 feet in height, forming greater than 25 percent cover, with trees forming less than 25 percent cover; shrub cover may be less than 25 percent in cases where the cover of each of the other life forms present is less than 25 percent and the shrub cover exceeds the cover of other life forms; does not include developing secondary associations dominated by tree species. 225

sod grass
a life form of graminoids that tends to develop a solid mat of grass, sedge, etc. over the ground by vegetative increase of rhizomes or stolons; resulting vegetation generally has few spaces between plants.

sparsely vegetated
describes vegetation with low total plant cover (generally less than 10 percent) that is scattered or nearly absent (less than 1 percent); areas with high cover of crustose lichen and no other vegetation are included here.

stomata
pores or openings for gas exchange that are generally concentrated on leaf surfaces.

subalpine
upper mountain vegetation immediately below the cold limits of tree and tall shrub growth.

subdesert
an area of xerophytic shrubby vegetation with a poorly-developed herbaceous layer.

submontane
an area where the influence of altitude (vertical relief) does not result in local climate regimes that are sufficiently different from the adjacent lowlands as to cause a complex vegetation-climate-soil zonation; generally includes the foothills of a mountain range; the lowland vegetation at the base of a mountain that displays vegetation zonation.

subpolar
geographically, the region immediately equatorward of the Arctic and Antarctic circles; climatically, winters are long and extremely cold, and summers are very short; only one month per year has a monthly average warmer than 10º C (50º F); as a rule, the ground is completely covered by snow for at least half a year; the region between the tundra and cold temperate forests or steppes.

subtropical
pertains to areas within tropical regions with variable (seasonal) temperature and moisture regimes; climatically, it has seasonal variation marked by dry/wet seasons rather than cold/hot seasons; parts of this region are subject to sub-0º C (32º F) temperatures but rarely have freezing periods of 24 hours or longer; in the United States this term includes southern Florida and the southern tip of Texas.

succulent
a plant with fleshy stems or leaves with specialized tissue for the conservation of water; a xeromorphic strategy for tolerating long periods of drought.

suffruticose
a somewhat shrubby plant in which the upper vegetative and flowering shoots die back to leave only the lower parts to survive unfavorable seasons.

synusia
an association of plant species with a similar life form and similar ecological requirements occurring together in the same habitat; sometimes called a "union"; most habitats are occupied by several synusiae, which may grow above each other in layers, beside each other, or in mixture; for example, an open tree synusia or layer over a grass-dominated synusia or layer.

tall grassland
graminoid-dominated vegetation usually over 1 meter or 3 feet tall when inflorescences are fully developed in temperate zones, and greater than 2 meters or 6 feet in tropical zones.

tall forb
broad-leaved herbaceous plants usually greater than 1 meter or 3 feet tall when inflorescences are fully developed.

talus
a sloping accumulation of coarse rock fragments at the base of a cliff.

temperate
geographically, the region between the polar and tropical regions; climatically, the region is moderate with distinct seasons of alternating long, warm summers and short, cold winters.

temporarily flooded
surface water present for brief periods during growing season, but water table usually lies well below soil surface. Often characterizes flood-plain wetlands. Equivalent to Cowardin's Temporary modifier.

tree
perennial, woody species life form with a single stem (trunk), normally greater than 4 to 5 meters or 13 to 16 feet in height; under certain environmental conditions, some tree species may develop a multi-stemmed or short growth form (less than 4 meters or 13 feet in height).

treeline
a zone where the normal growth of trees is limited; cold temperatures often combined with drought form the upper or arctic treeline, and drought combined with hot temperatures form the lower or arid treeline.

tropical
geographically, the area between the Tropic of Cancer (23º 27' N) and the Tropic of Capricorn (23º 27' S), which includes tropical montane and alpine zones; climatically, the tropics are described as either the equatorial limits of freeze or, in temperate marine locations without freezing, the 65º F isotherm for the coldest month of the year; generally, tropical regions are characterized by high mean temperatures, small annual variation in temperature, and abundant rainfall throughout the year, although mountainous areas within the tropics are more variable.

tuft-tree
woody plant with large leaf-fronds or rosulate branches at the tips of major trunk(s); for example, palms and tree ferns.

tundra
the treeless region north of the Arctic Circle (arctic tundra) or above the treeline of high mountains (alpine tundra) and also on some sub-Antarctic islands; characterized by very low winter temperatures, short cool summers, permafrost below a surface layer subject to summer melt, short growing season, and low precipitation.

tussock
graminoid life form consisting of bunch-like tufts, sometimes more than 1 meter or 3 feet tall, in which the hard, old, withered leaves are intermingled with the fresh, young, green leaves.

vascular plant
a plant with water and fluid conductive tissue (xylem and phloem); includes seed plants, ferns, and fern allies.

winter-rain
a climatic regime characterized by precipitation that occurs mostly as rain during cool winters that alternate with dry, hot summers; often associated with sclerophyllous vegetation.

woody
containing lignified plant tissue.

woody plant
plant species life form with woody tissue and buds on that woody tissue near or at the ground surface or above; plants with limited to extensive thickening by secondary woody growth and with perennating buds; includes phanerophytes and chamaephytes of Raunkier.

xeromorphic
describes plants with morphological and physiological characters that tolerate persistently low water availability, such as succulence, specialized leaf surfaces for light reflectance or water retention, opportunistic leaf growth, leaf-size reduction with increased thickness and sunken stomata, revolute margins, or stem and leaf modification to form thorns or spines.