loosestrife and ironweed. Z 



Seasonally flooded areas, although they may intergrade with the > 



wooded swamp type, often support a less hydric vegetation. Annual q 



plants, tolerant of mesic conditions, often colonize flood-plain sites < 



which are only periodically inundated. A rather unusual community, rn 



the vernal pools of California, is included in this category. These areas f~ 



exhibit a unique flora in which the growth form of some of the plants z 



changes from truly aquatic to spiny xerophytic as the depression dries ^ 



out. 



The inland saline wetlands occur in poorly drained, semi-arid re- 

 gions, where high temperature evaporates much of the water, leaving 

 the salts behind. Where insufficient leaching occurs the salts accumu- 

 late, forming alkali soils. Plants on such sites are known as halophytes 

 and are characteristic of saline flats and marshes that may be per- 

 manently or periodically flooded. 



In order to avoid unnecessary proliferation of classification schemes, 

 we have utilized the U.S. Fish and Wildlife Service system (Martin et 

 al. 1953; Shaw and Fredine 1956) with some elaboration. This involves 

 1 1 of the 20 wetland categories described, 8 fresh water and 3 saline. 

 We have added one special type, the riparian habitat, which is often a 

 gallery-type forest restricted to stream margins, especially in drier re- 

 gions. This vegetation may be considered transitional between a true 

 bottomland wetland and a mesic upland type. Examples include certain 

 canyon and stream border communities that occur in California, 

 Arizona, and the Great Plains. 



Kuchler ( 1964) has developed a map of the potential natural vegeta- 

 tion of the United States. Of the 1 16 vegetation types recognized, 10 

 describe inland wetlands. Table I has been included to show how these 

 types fall into the classification employed here. 



In the classification of wetland types that follows, the distinctive fea- 

 tures and floristic characteristics of each are summarized. The codes 

 for each type are used in the inventory to characterize the wetlands 

 described. As would be expected, a given wetland may exhibit features 

 of more than one category. The first letter of the code indicates 

 whether the wetland is fresh (F), saline (S), or riparian (R). The num- 

 bers refer to the types as used by the U.S. Fish and Wildlife Service. 

 The final letters indicate whether wetland is a marsh (M), a shrub 

 swamp (Ss), a wooded swamp (Sw), or a bog (B). Calcareous habitats 

 may be designated by (Ca) at the end of the code. 



Fresh-Water Wetland Types 



SEASONALLY FLOODED BASINS AND FLATS (F-l). These 

 sites are inundated periodically, but not flooded during the growing 

 season. They occur along water courses and on flood plains, especially 

 in the lower Mississippi drainage and in the Southeast. They also in- 

 clude temporarily flooded basins in the Panhandle of Texas and the 



