~ 22 NATURAL HISTORY BULLETIN. 



counties, 1896, Barnes & Miller ; Charles City, Aug., 1875, 

 Arthur; Muscatine, 1897, Ball. 



The following varieties also occur, in Iowa, specimens of 

 each, determined by Dr. N. L. Britton being in the herbarium 

 of the Iowa Agricultural College at Ames. 



10. C. strigosus robustior Kunth. Enum., 11, 88 (1837). 



Illus. Flora, i, 243. 



Habit and range of the type, but less common. Spikelets 

 nearly an inch long, 10-25 flowered. 



Ames and Iowa City, Hitchcock; Woodbine, 187S, Burgess. 



11. C. strigosus capitatus Boeckl. Linnsea, xxxvi, 347 



(1869-70). 



Illut. Flora, 1, 243. 



Low ground in marshes, rare; not before reported from the 

 state. A very small, slender form, the plants only a few 

 inches tall with the 5-15 flowered spikelets arranged in capi- 

 tate clusters. It is possible that this is merely a state of the 

 type produced by a very dry season. 



Algona, Hitchcock; Emmet county, in a marsh \yi miles 

 east of Armstrong, Aug., 1896, Cratty. 



12. C. strigosus compositus Britton. Bull. Torr. Club, 



xin, 212 (1886). 



Illus. Flora, 1, 243. 



Rather rare in swamps or low ground. The umbel very 

 compound, the 4-6 flowered spikelets clustered in cylindrical 

 heads. Plants 6-18 inches high. 



Charles City, Arthur; Lawler, 1890, Rolfs; Scott county, 

 Barnes & Miller; Iowa Lake, Emmet county, Aug., 1897, 

 Cratty. 



13. C. filiculmis Vahl. Enum., 11, 328 (1806). 



Illus. Flora, 1, 245, fig. 571; Cray's Man., 6th ed., 570; Arthur, Fl. Iowa, 33; 

 Hitchcock, PI. Ames, 523; MacMillan, Metas. Minn. Val., 92; Tracy, 

 Fl. Mo., 91; Brendel, F). Peoriana, 61 ; Bruhin, Fl. Wis., 278; Webber, 

 Fl. Neb., 99; Fink, Iowa Acad. Sci., iv, 105. 



Sandy soil, margins of streams and lakes; most frequent in 



the eastern half of the state. Quite variable. 



