A GUIDE AND KEY TO AQUATIC PLANTS 75 



17. S. longirostra (Micheli) J. G. Smith — Usually found in the 

 Coastal Plain, noted in acid, open ponds in Georgia. 



18. S. mscosa C. Mohr — Restricted to North Florida and South 

 Alabama in marshes. 



3. Echinodorus L. C. Rich. 



1. Achene with little or no beak, stamens 9; plants small 1. E. tenellus. 



(usually less than 1.5 dm.), leaves narrow. 

 1. Achene prominently beaked, stamens 12-21; plants 2. 

 usually longer, leaves broadened, 



2. Flowering stems erect; stamens 12 2. E. cordifolia. 



2. Flowering stems arching or creeping, often root- 3. E. radicans. 

 ing at nodes; stamens about 21. 



1. E. tenellus (Martins) Buchenau — Should range over most of our 

 territory, not noted by the writers. Called by Small Helanthium 

 parvulum (Engclm.) Britton. 



2. E. cordijolius (L.) Griseb. Burhead — Should also be well dis- 

 tributed over our area, not common. 



3. E. radicans (Nutt.) Engelm. Burhead — Well distributed over 

 our area, but infrequent. Prefers hard or neutral waters, noted 

 principally in alluvial aquatic areas. 



4. Lophotocarpus T. Durand 



L. calycinus (Engelm.) J. G. Smith — Confined to western part of 

 our territory. Noted along Mississippi River just north of our 

 territory. 



HYDROCHARITACEAE Frog-bit family 



1. Anacharis Planch 



1 . Leaves 3 in whorls; petals less than S mm. long or want- \. A. canadensis. 



ing. 

 1. Leaves 4 in whorls; petals prominent, about 1 cm. long. 2. A. densa. 



1. A. canadensis (Michx.) Planch. Waterweed — Occurs mostly 

 north of our territory but present in Reelfoot Lake, Tennessee. 



2. A. densa (Planch.) Victorin — Occurs as an escape from aquaria. 

 Collected in Chatham County, Georgia, where it harbored Anopheles 

 quadrimaculatus . Besides the above two, there is a third, very local 

 species in middle Tennessee. 



2. Vallisneria [Mich.] L. 



V. americana Michx. Eelgrass — Some authorities differentiate two 

 species of Vallisneria in the southeast, but these two are very similar. 

 Except along the Gulf Coast, Eelgrass is very rare (or absent) in our 

 territory. 



