98 CONTRIBUTIOITS FKOM THE NATIONAL HERBARIUM. 



9. Scirpus cyperinus (L.) Kunth. Wool grass. 

 Swales and wet meadows; common, especially in the southern and eastern part of 



our range. Aug.-Sept. Atlantic coast to Tenn, and Ark. 

 9a. Scirpus cyperinus condensatus Fernald. 



Swales and open meadows; Riverdale and Lanham. Sept. Northern Atlantic 

 states. 



10. Scirpus eriophorum Michx. 



Swales and among openings along streams; common. July-Sept. Atlantic states 

 and lower Mississippi Valley. July-Sept. (Included in S. cyperinus in Britt. & 

 Brown, Illustr. Fl.) 



11. Scirpus pol3T)hylIus Vahl. 



Swales, ditches, and wet wood borders; common. July-Oct. Eastern U. S. 



Often conspicuously proliferous in the autumn, the inflorescence bearing few to 

 several well-developed leafy plantlets, the culms leaning, bringing the plantlets 

 near the earth. A form with spikelets as much as 5 mm. long has been called S. 

 polyphyllus macrostachys Boeckl. 



12. Scirpus sylvaticus L. 



Marshes along the Eastern Branch ; rare. Aug. Eastern U. S. 



13. Scirpus atrovirens Miihl. 



Swales, ditches, and wet wood borders; common along the Potomac. June-Aug. 

 Northern states, south to Ga. 



14. Scirpus georgianus Harper. 



Wet sandy and alluvial soil in the flood plain of the Potomac at Long Bridge and 

 southward. June-July. Northern states, south to Ga. (Included in S. atrovirens in 

 Britt. & Brown, Illustr. Fl.) 



8. ERIOPHOBTJM L. Cotton grass. 



1. Eriophorum virginicum L. 



Open ground in magnolia bogs; Terra Cotta and eastward; infrequent. July-Sept. 

 Northern states, south to Ga. 



9. FUIRENA Rottb. 



1. Fuirena hispida Ell. 



Frequent in open ground in magnolia bogs below the fall line. Aug.-Sept. Southern 

 states, north to N. J. 



At or after maturity producing ovate tubers close to the base of the culm. 



10. HEMICARPHA Nees & Arn. 



1. Kemicarpha micrantha (Vahl) Pax. 



Open wet sandy ground; Zoological Park and Potomac bottom land near Lock No. 

 9. Sept. Throughout the U. S. 



11. RYNCHOSPORA Vahl. 



Achene bearing a beak 2-3 times its own length, the two together about 2 cm. long. 

 Spikelets in large squarrose heads. 

 Bristles shorter than the body of the achene; heads rather loose. . .1. R. corniculata. 

 Bristles about twice as long as the body of the achene ; heads compact. 



2. R. macrostachya. 

 Achene bearing a small tubercle or beak much shorter than the body, the two together 

 not over 8 mm. long. 

 Achene transversely wrinkled : bristles not over half the length of the achene. 



3. R. cymosa. 



