CYPEKACEAE 41 



8. C. ferox Vahl. Like the last but leaves smooth -margined : umbel 

 more simple : spikelets stouter, rather longer and about \ f/ thick : scales 

 rigid, yellowish-brown. Collected on sand-bars along the Missouri 

 Eiver. June-October. 



9. C. strigosua L. Culms 6'-3 high : leaves rough-margined, those 

 of the involucre exceeding the rays : umbels simple to very compound : 

 spikelets 4-many- flowered, flat, M'-W long: scales straw-colored with 

 a green midrib, acutish : achene linear-oblong. Common throughout 

 in damp soil. Exceedingly variable. June-October. 



Var. robustior Kunth. With a large compound umbel : spikelets 8' 

 or more long and 10-25-flowered. Frequent with the type. 



10. C. ovularis (Michx.) Torr. 6'-2 high: leaves very rough-mar- 

 gined : spikelets 2 // -3 // long, about 3-flowered, in dense globose, sessile 

 or peduncled heads : scales green, several-nerved. Sparingly adventized 

 at Sheffield. May-September. 



11. C. filiculmis Vahl. Culms slender and wiry, 6M8' high : spike- 

 lets densely clustered, in one sessile head, or in 1-7 additional heads on 

 spreading rays: spikelets 4-1 1-flowered, 2i // -6 // long : scales strongly 

 nerved. Dry sterile soil, throughout, especially in the southern part, but 

 not common. May -September. 



12. C. Bushii Britton. Culms 1-2J high : umbel 2-9-rayed, the 

 spikelets in loose, ovoid spikes : spikelets loosely 6-12-flowered, 4 // -8 // 

 long : scales strongly nerved, acuminate. One clump was found native 

 in sandy soil in Rush bottom at Courtney many years ago, and it has 

 rarely been adventized along the railroad at the same place. June-Sep- 

 tember. 



2. KYLLINGA Rottb. 



Spikelets of tin ee or four two-ranked scales, the two lower empty, the 

 third with a perfect flower and the fourth empty or staminate. Spikelets 

 densely aggregated in 1-3 sessile heads and subtended by a 3-leaved invo- 

 lucre. Style 2-cleft and achene lenticular. Perianth none. 



1. K. pumila Michx. A densely tufted annual, 2 / -10 / high with usu- 

 ally 3-lobed heads of spikelets, 3 // -4 // long: spikelets \\" long. In 

 moist soil, mostly confined to the northeastern part, where it is often very 

 abundant. July-September. 



3. DULICHIUM L. 



Perennial. Stems jointed, terete and hollow, with numerous 3-ranked 

 leaves, the lower reduced to sheaths. Spikelets 2-rauked in axillary spikes, 

 linear. Scales 2-ranked and decurrent on the axis. Perianth of 6-9 

 downwardly barbed bristles. Stamens three. Style 2-cleft, persistent on 

 the linear-oblong achene as a beak. 



1. D. arundinacea (L. ) Britton. 2-3 high : leaves 2 / -3 / long, 2" 

 wide : spikelets over 6 X/ long, 6-12-flowered. Common in bogs along the 

 bluffs about three miles west of Sibley. 



