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,-.. 00 r-- C) c.) ,~', -- The second type is a group of salt tolerant species (halophytes) that include absorbed salt and store it in high concentrations within stem, leaf, or special storage organs, Such plants may actively sequester ions into large or numerous small vacuoles, developini succulent leaves o~ stems in the process, Under these circumstances, since no rigid structure provides a counter p~essure between vacuole and cytoplasm, o~ganic osmoregulators are synthesized to provide balance, Solutes of this sort reported to occur in halophytes include p~oline-, glycine-, and alanine-betaine, glycerol, sorbitol, mannitol, and some sulfonium derivatives (Luttge and Smith, 1984), The third type includes the extreme halophytes, such as the mangrove Avicennia, and the salt marsh cord grass Spartina, These plants include absorbed salt, but they are believed to actively sto~e these salts in specialized structures, te~med salt glands. These glands are connected to the leaf surface and function to exc~ete salt to the leaf's exte~io~. Active transport is believed to be involved in the uptake of solute into the gland, but the actual secretion p~ocess is thought to result from increased hydrostatic pressure, although this is still an area of controve~sy (see Thomson, 1975, for discussion) . The significance of these halophyte groups is that salt balance is achieved within the leaves and in the vicinity of both chloroplasts and primary photosynthetic products. Energy use fo~ salinity control is thus likely to be more efficient. Second, salts collected from the soil are not excluded back to the soil fo~ eventual deposit into groundwaters, but rather are packaged in a way that might be managed through crop harvesting or cleaning, C, Processes within Emergent Salt Marsh Species The following material will examine transpiration, production, and chemical composition separately and establish performance expectations for technology implementation along the Colorado River, between Eagle and G~and Junction. 1. Transpiration Transpiration rates depend upon the number and aperature size of stomata, the root-shoot ratio, light, tempe~ature, the diffusion pressure deficit and wind speed, The first two a~e botanical featu~es; the latter facto~s determine how a given plant will respond in different environments. The botanical features determine the capacity particula~ species have to utilize water efficiently, The STEP process will utilize species that have the capacity to transpire at the highest possible rates under the broadest of environmental conditions, The~efore, cont~ary to established ag~icultural 16,