13 



mean higher high tide The average height of the higher of two 

 unequal daily high tides over 19 years. 



mean low water The average height of the low water over 19 

 years. 



mean lower low water The average height of the lower of two 

 unequal daily low tides over 19 years. 



mean tide level A plane midway between mean high water 

 and mean low water. 



mesohaline Term to characterize waters with salinity of 5 to 

 18 °/oo, due to ocean-derived salts. 



mesophyte Any plant growing where moisture and aeration 

 conditions lie between extremes. (Plants typically found in 

 habitats with average moisture conditions, not usually dry 

 or wet.) 



mesosaline Term to characterize waters with salinity of 5 to 

 18 °/oo, due to land-derived salts. 



mineral soil Soil composed of predominantly mineral rather 

 than organic materials (see page 44). 



mixohaline Term to characterize water with salinity of 0.5 to 

 30 °/oo, due to ocean salts. The term is roughly equivalent to 

 the term brackish. 



mixosaline Term to characterize waters with salinity of 0.5 to 

 30 °/oo, due to land-derived salts. 



mud Wet soft earth composed predominantly of clay and 

 silt— fine mineral sediments less than 0.074 mm in diam- 

 eter (Black 1968; Liu 1970). 



needle-leaved deciduous Woody gymnosperms (trees or 

 shrubs) with needle-shaped or scale-like leaves that are 

 shed during the cold or dry season; e.g., bald cypress (Taxo- 

 dium distichum). 



needle-leaved evergreen Woody gymnosperms with green, 

 needle-shaped, or scale-like leaves that are retained by 

 plants throughout the year; e.g., black spruce {Picea 

 mariana). 



nonpersistent emergents Emergent hydrophytes whose 

 leaves and stems break down at the end of the growing 

 season so that most above-ground portions of the plants 

 are easily transported by currents, waves, or ice. The 

 breakdown may result from normal decay or the physical 

 force of strong waves or ice. At certain seasons of the year 

 there are no visible traces of the plants above the surface of 

 the water; e.g., wild rice (Zizania aquatica), arrow arum 

 (Peltandra virginica). 



obligate hydrophytes Species that are found only in 

 wetlands— e.g., cattail {Typha latifolia) as opposed to ubiq- 

 uitous species that grow either in wetland or on upland— 

 e.g., red maple {Acerrubrum). 



oligohaline Term to characterize water with salinity of 0.5 to 

 5.0 °/oo, due to ocean-derived salts. 



oligosaline Term to characterize water with salinity of 0.5 to 

 5.0 °/oo, due to land-derived salts. 



organic soil Soil composed of predominantly organic rather 

 than mineral material. Equivalent to Histosol (see page 44). 



persistent emergent Emergent hydrophytes that normally 

 remain standing at least until the beginning of the next 

 growing season; e.g., cattails {Typha spp.) or bulrushes 

 (Scirpus spp.). 



photic zone The upper water layer down to the depth of effec- 

 tive light penetration where photosynthesis balances 



respiration. This level (the compensation level) usually 

 occurs at the depth of 1% light penetration and forms the 

 lower boundary of the zone of net metabolic production. 



pioneer plants Herbaceous annual and seedling perennial 



plants that colonize bare areas as a first stage in secondary 



succession. 

 polyhaline Term to characterize water with salinity of 18 to 



30 °/oo, due to ocean salts. 

 polysaline Term to characterize water with salinity of 18 to 



30 °/oo, due to land-derived salts. 



saline General term for waters containing various dissolved 

 salts. We restrict the term to inland waters where the 

 ratios of the salts often vary; the term haline is applied to 

 coastal waters where the salts are roughly in the same 

 proportion as found in undiluted sea water (see page 25). 



salinity The total amount of solid material in grams con- 

 tained in 1 kg of water when all the carbonate has been 

 converted to oxide, the bromine and iodine replaced by 

 chlorine, and all the organic matter completely oxidized. 



sand Composed predominantly of coarse-grained mineral 

 sediments with diameters larger than 0.074 mm (Black 

 1968) and smaller than 2 mm (Liu 1970; Weber 1973). 



shrub A woody plant which at maturity is usually less than 

 6 m (20 feet) tall and generally exhibits several erect, 

 spreading, or prostrate stems and has a bushy appearance; 

 e.g., speckled alder (Alnus rugosa) or buttonbush (Cepha- 

 lanthus occidentalis). 



sound A body of water that is usually broad, elongate, and 

 parallel to the shore between the mainland and one or more 

 islands. 



spring tide The highest high and lowest low tides during the 

 lunar month. 



stone Rock fragments larger than 25.4 cm (10 inches) but less 

 than 60.9 cm (24 inches). 



submergent plant A vascular or nonvascular hydrophyte, 

 either rooted or nonrooted which lies entirely beneath the 

 water surface, except for flowering parts in some species; 

 e.g., wild celery (Vallisneria americana) or the stoneworts 

 {Chara spp.). 



terrigenous Derived from or originating on the land (usually 

 referring to sediments) as opposed to material or sediments 

 produced in the ocean (marine) or as a result of biologic 

 activity (biogenous). 



tree A woody plant which at maturity is usually 6 m (20 feet) 

 or more in height and generally has a single trunk, un- 

 branched to about 1 m above the ground, and a more or less 

 definite crown; e.g., red maple (Acer rubrttm), northern 

 white cedar (Thuja occidentalis). 



water table The upper surface of a zone of saturation. No 

 water table exists where that surface is formed by an 

 impermeable body (Langbein and Iseri 1960:21). 



woody plant A seed plant (gymnosperm or angiosperm) that 

 develops persistent, hard, fibrous tissues, basically xylem; 

 e.g., trees and shrubs. 



xerophyte, xerophytic Any plant growing in a habitat in 

 which an appreciable portion of the rooting medium dries 

 to the wilting coefficient at frequent intervals. (Plants 

 typically found in very dry habitats.) 



