94 PUBLIC HEALTH BULLETIN NO. 2 86 



2. F. pumila Torr. Umbrella-grass — Mostly of Coastal Plain distri- 

 bution, supposed to occur most frequently in brackish marshes, but 

 collected from acid pond margins. Ranges from Florida to north of our 

 territory. 



3. F. breviseta Coville — Common in Coastal Plain, Florida north and 

 west to the limits of our territory. 



4. F. squarrosa Miclix. — Difficult to distinguish superficially from 

 the preceding. Found also in acid places, Coastal Plain, Florida north 

 and west to beyond the limits of our territory. 



7. Dichromena Michx. 



1. Bracts subtending flower clusters 4-6, linear; lubercle 1. D. color ala. 



not decurrent on the sides of the achene. 



1. Bracts 7-10, lanceolate; tubercle decurrent on sides of 2. D. laiifolia. 



achene. 



1. D. colorata, (L.) Hitchc. White-top Rush — Coastal Plain, 

 Florida north and west to beyond the limits of our territory in less 

 acid situations than the following species. Common along tbe coast. 



2. D. latifolia Baldw. — Range similar to preceding, habitat more 



acid. 



8. Psilocarya Torr. 



1. Tubercle higher than wide, as long or nearly as long as 1. P. corymbifera. 



achene, somewhat decurrent. 

 1. Tubercle broader than long, much shorter than acliene, 2. P. niUns. 



not decurrent. 



1. P. corymbifera (C. Wright) Britton — Ajound ponds in acid situa- 

 tions. Coastal Plain, Florida, Georgia, and probably Alabama and 

 Mississippi. 



2. P. nitens (Vahl) Wood. Bald-rush— Similar situations to the above 

 but more widespread, Florida north and west to beyond the limits of 

 our territory. A third species, P. scirpoides Torr., may enter our 

 territory in North Carolina, and the senior writer has one or two 

 Georgia specimens which have been determined as this. 



9. Rhynchospora Vahl 



1. Tubercle of achene over twice as long as achene 2. 



1. Tubercle as long as achene or shorter ^ 6. 



2. Tubercle very slender over all; spikelets in 1. R. tracyi. 



1-4 dense, globose heads. 

 2. Tubercle broadened at the ba.se, narrowed 3. 

 upward; spikelets pedicelled, 



3, Perianth-bristles sliorter than achene- . 2. R. corniculata. 



3. Perianth-bristles much longer than achene 4. 



4. Plant not stoionifcrou.s; spikelets in clusters 3. R. macrostachya. 



of 10-50 together. 

 4. Plant stoloniferous; spikelets few in each 5. 

 cluster. 



