Vegetation unit - A patch, grouping, or zone of plants evident in overall plant cover, which appears distinct 

 from other such units because of the vegetation's structure and floristic composition; a given unit is typi- 

 cally topographically distinct and typically has a rather uniform soil, except possibly for relatively dry mi- 

 crosites (e.g., tree bases, old tree stumps, mosquito ditch spoil piles, and small earth hummocks) in an 

 otherwise wet area or relatively wet microsites (e.g., small depressions) in an otherwise dry area. 



Very long duration (flooding) - A duration class in which inundation for a single event is greater than 1 

 month. 



Vertisols - Shrinking and swelling dark clay soils; most common in Texas. 



Very poorly drained - A condition in which water is removed from the soil so slowly that free water re- 

 mains at or on the surface during most of the growing season. 



Water mark - A line on vegetation or other upright structures that represents the maximum height reached 

 in an inundation event. ^ 



Water table - The zone of saturation at the highest average depth during the wettest season; it is at least six 

 inches thick and persists in the soil for more than a few weeks. 



Wetiands - As used herein, areas that under normal circumstances have hydrophytic vegetation, hydric 

 soils, and wedand hydrology. 



Wedand boundary - The point on the ground at which a shift from wedands to nonwedands occurs. 



Wedand determination - The process by which an area is identified as a wedand or nonwedand. 



Wedand hydrology - In general terms, permanent or periodic inundation or prolonged soil saturation suffi- 

 cient to create anaerobic conditions in the soil. 



Wedand indicator status - The exclusiveness with which a plant species occurs in wetiands; the different 

 indicator categories (i.e., facultative species, and obligate wedand species) are defined elsewhere in this 

 glossary. 



Wooded swamp - A wedand dominated by trees; a forested wedand. 



Zone of influence - The area contiguous to a ditch, channel, or other drainage structure that is direcdy af- 

 fected by it. 



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