94 CONTEIBUTIONS FKOM THE NATIONAL HERBAEIUM. 



3. Cyperus flavescens L. 



Wet banks and springy places; along Piney Branch, Rock Creek, Eastern Branch, 

 and Potomac; frequent. July-Oct. Eastern U. S. 



4. Cyperus aristatus Rottb. 



Alluvial and sandy flats; flood plain of Rock Creek and the Potomac. July-Sept. 

 Throughout the U. S. (C. inflexus Muhl.) 



Dried specimens have the odor of slippery elm. 



5. Cyperus fuscus L. 



AdventiA-e in wet waste ground near wharves; Washington and Alexandria; ap- 

 parently infrequent, Aiig.-Sept. Ballast grounds of Atlantic ports; European. 



6. Cyperus erythrorhizos Muhl. 



Common in alluvial flats in the wet sandy flood plain of the Potomac below 

 Washington. Eastern and middle states. 



On ground which becomes dry in late summer the plants form dwarf tufts; this 

 form is the variety pumilus Engelm. 



7. Cyperus speciosus Vahl. 



Sandy margins of streams; common along the Potomac south of Washington, infre- 

 quent to the east, not found in the northwest. Aug.-Oct. Eastern and middle 

 states. (C. michauxiunus Schult.; included in C. ferax Rich, in Gray's Manual.) 



8. Cyperus pseudovegetus Steud. 



Frequent in alluvial soil among rocks; margin of the Potomac from Great Falls to 

 below Washington. July-Sept. Atlantic and Gulf coasts, also in Kans. and Mo. 

 (C. virens of Ward's Flora.) 



9. Cyperus filiculmis Vahl. 



Common in dry sandy open ground and open pine woods. June-Sept. Eastern 

 and middle states. 



10. Cyperus rotundus L. Nut grass. 

 Found in 1899 in waste ground west of the old fishpond. Oct. Atlantic and Gulf 



states; abundant and often a troublesome weed in the South. 



11. Cyperus esculentus L. 



Common in low wet waste ground, especially along the Potomac. July-Oct. 

 Throughout the U. S. (C. phymatodes Muhl.) 



12. Cjrperus strigosus L. 



•Common in alluvial ground near streams, everywhere. Aug.-Oct. Throughout 

 the U. S. 



13. Cyperus ovularis (Michx.) Torr. 



Dry sandy wood borders and old fields; frequent throughout. July-Sept. Atlantic 

 and middle western states. 



14. Cyperus torreyi Britton. 



Rare; found in a low field at Bennings. July-Sept. Atlantic Coastal Plain. (C 

 cylindricus Britton, not Boeckl.) 



15. Cyperus dipsaciformis Femald. 



Dry sandy woods; frequent. July-Sept. N.J. and southward, and in Ky. (In- 

 cluded in C. retrofractus in Britt. & Brown, Illustr. Fl.) 



16. Cyperus retrofractus (L.) Torr. 



Dry sandy or rocky soil; Munger's Hill. Oct. Atlantic Coastal Plain and in the 

 lower Mississippi Valley. 



17. C3T»erus laucastrieusis Porter. 



Common in low, sandy or gravelly, open ground along the Potomac. July-Oct. 

 Middle Atlantic states. 



18. Cyperus refractus Engelm. 



Common in dry wood borders and banks along Rock Creek, Eastern Branch, and 

 Potomac. N. J. to Ga. and Mo. 



