1. This appendix contains three sections. Section 1 is a subset of the 

 regional list of plants that occur in wetlands, but includes only those spe- 

 cies having an indicator status of OBL, FACW, or FAC. Section 2 is a list of 

 plants that coiranonly occur in wetlands of a given region. Since many geo- 

 graphic areas of Section 404 responsibility include portions of two or more 

 plant list regions, users will often need more than one regional list; thus. 

 Sections 1 and 2 will be published separately from the remainder of the 

 manual. Users will be furnished all appropriate regional lists. 



2. Section 3, which is presented herein, describes morphological, 

 physiological, and reproductive adaptations that can be observed or are known 

 to occur in plant species that are typically adapted for life in anaerobic 

 soil conditions. 



Section 3 - Morphological, Physiological, and Reproductive 



Adaptations of Plant Species for Occurrence in Areas 



Having Anaerobic Soil Conditions 



Morphological adaptations 



3. Many plant species have morphological adaptations for occurrence in 

 wetlands. These structural modifications most often provide the plant with 

 increased buoyancy or support. In some cases (e.g. adventitious roots), the 

 adaptation may facilitate the uptake of nutrients and/or gases (particularly 

 oxygen). However, not all species occurring in areas having anaerobic soil 

 conditions exhibit morphological adaptations for such conditions. The 

 following is a list of morphological adaptations that a species occurring in 

 areas having anaerobic soil conditions may possess (a partial list of species 

 with such adaptations is presented in Table CI) : 



a. Buttressed tree trunks. Tree species (e.g. Taxodiun distiohun) 

 ~ may develop enlarged trunks (Figure CI) in response to frequent 



inundation. This adaptation is a strong indicator of hydro- 

 phytic vegetation in nontropical forested areas. 



b. Pneumatophores. These modified roots may serve as respiratory 

 organs in species subjected to frequent inundation or soil 

 saturation. Cypress knees (Figure C2) are a classic example, 

 but other species (e.g., Nyssa aquatiaa, Rhizophora mangle) may 

 also develop pneumatophores. 



c. Adventitious roots. Sometimes referred to as "water roots, 



~ adventitious roots occur on plant stems in positions where roots 

 normally are not found. Small fibrous roots protruding from the 

 base of trees (e.g. Salix nigra) or roots on stems of herbaceous 



C2 



