CYPERACEAE 45 



18. Cyperus eohinatua (Ell.) Wood. Baldwin 's Cyperus. (Man. 

 p. i66 ; I. F. f.574.) lu dry soil, N. C. to Mo., Pla. and Tex., and ad- 

 ventive northward. — Pennsylvania : Bartram's Garden. 



4. ERIOFHORUM L. 



Spikelet solitary : involucre of a short hract or wanting, i. E. vaginatum. 

 Spikelets several, umbellate or capitate : involucre of 1-4 bracts. 

 Achenes obovoid, obtuse : spikelets umbellate. 2. B. polystachyon. 



Achenes linear-oblong, acute : spikelets capitate or some of them peduncled. 

 Leaf-blades channeled : perianth-bristles 4-6 times as long as the scales, 

 bright white. 

 Perianth -bristles i-i .5 cm. long : peduncles and upper part of scape 



smooth. 3. E. gracile. 



Perianth-bristles 2-2. 5 cm. long : peduncles and upper part of scape rough. 



4. E. paucinervium. 

 Leaf -blades flat : perianth-bristles 3 times as long as the scale, brown. 



5. E. Virginicum. 



1. Eriophorum vaginatum L. Sheathed Cotton-grass. (Man. p. 



181 ; I. F. f. 638. ) In bogs or meadows, Newf. to Alaska, Mass., Pa. and 

 Minn. Also in Eu. and Asia. — Pennsylvania : Monroe, Tobyhanna 

 Mills, Tannersville, Lehigh Pond ; Wayne. 



2. Eilophormn polystachyon L. Tai,i< Cotton-grass. (Man. p. 



182 ; I. F. /. 64/.) In bogs or meadows, Newf. to Alaska, N. J., Ga. and 

 Neb. Also in Eu. and Asia. — Pennsylvania : Monroe, Pocono ; 

 Erie. • 



3. Eriophorum gracile Koch. Slender Cotton -grass. (Man. p. 

 182.) In bogs and ponds, Newf. to Alaska, N. J., Pa. and Mo. Also in 

 Eu. and Asia. —Pennsylvania : Northampton ; Bucks ; Monroe ; Pike ; 

 Chester. 



4. Eriophorumpauoinervium(Engelm. ) A. A. Eaton. Few-nerved 

 Cotton-grass. (Man. p. 182; I. P./. 642, as £. g- facile.) In bogs, N. 

 B. to N. J. and 111. — Pennsylvania : Monroe, Tobyhanna Mills ; Susque- 

 hanna. 



5. Erlophormu Virginicum L. Virginia Cotton-grass. (Man. p. 

 182 ; I. F. /. 64J.) In bogs or wet sand, Newf. to Man., Fla. and Neb. 

 — Pennsylvania : Wayne ; Monroe ; Lancaster ; Centre ; Craw- 

 ford ; Erie ; Montgomery ; Bucks ; Schuylkill ; Montour ; 

 Chester ; Delaware. 



5. SCIRPUS L. 



A. Involucre of a single bract, or wanting. 

 Spikelets solitary, or rarely 2 in No. 3, terminal. 

 Involucre wanting. i. S. pauciflorus. 



Involucre present, of a single bract. 

 Bract mostly shorter than the spikelet : scales acuminate : plants not 



aquatic. 2. 5. planifolius. 



Bract mostly longer than the spikelet : scales acute : plants aquatic. 



3. 5. subterminalis. 

 Spikelets normally more than i, usually several or numerous, often appar- 

 ently lateral. 



