A GUIDE AND KEY TO AQUATIC PLANTS 107 



2. H. reniformis R. & P. Mud-plantain — Georgia northward and 

 westward, like others of the genus seeming to prefer neutral or alka- 

 line waters. 



3. H. limosa (Swartz) Willd. — Range embraces all of our territory, 

 but not common. 



2. Pontederia L. 



P. lanceolata Nutt. Pickerel-weed — All of the Pickerel-weeds ob- 

 served by the writers in our territory are included under this species, 

 although it may be that P. cordata L. could also be differentiated. 

 One of the most frequent aquatic plants over most of our range and 

 found in a wide variety of aquatic situations. The shape of its 

 leaves varies considerably from linear to very broad and lobed at 

 the base. 



3. Eichhornia Kunth 



E. crassipes (Mart.) Solms. Water Hyacinth — Coastal Plain, over 

 most of our territory, but most abundant in Florida, Georgia, and 

 westward along the Gulf. In Florida is occasionally so abundant as 

 to impede navigation. Often grows in enormous pure masses and can 

 be found in association with Anopheles quadrimaculatus. Another 

 species, E. paniculatus (Spreng.) Solms, is said to occur in peninsular 

 Florida. 



JUNCACEAE Rush family 



1. Juncus [Tourn.] L. 



1. Plants creeping or forming mats in or OD the surface of 1. J. re-pens. 



the water. 



1. Plants erect and emergent 2. 



2. Stem appearing to continue upward beyond 3. 



inflorescence. 



2. Inflorescence terminal 4, 



3. Sheaths at base of stem without leaf-blades 2. J. effusus. 



3. Sheaths at base of stem with round blades 3. /. coriaceus 



4. Leaves with node-like septa 6. 



4. Leaves flat without node-like septa 5. 



5. Heads of inflorescence 5-15 flowered; heads usually 4. J. marginaius. 



few. 



5. Heads of inflorescence 2-5 flowered; heads usually 5. J. hiflorus. 

 many. 



6. Clusters reduced to only a single flower 6. J. abortivus. 



6. Clusters of inflorescence with many flowers 7. 



7. Capsule truly subulate 8. 



7. Capsule ellipsoid to linear-lanceolate in outline some- 11. 

 times acute or mucronate at apex but not truly 

 subulate. 



8. Uppermost leaf-sheath with very short blade 7. J. megacephalus. 



or none (at most 1-2 cm. long). 



8. Uppermost leaf-sheath with well-developed 9. 

 blade (3 cm. long or more). 



