CYPERACEAE 41 



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

 more simple : spikelets stouter, rather longer and about V^ thick : scales 

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

 Eiver. June-October. 



9. C. strigosus 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, 4^^-12'^ long: scales straw-colored with 

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

 in damp soil. Exceedingly variable. June-October. 



Var. robustior Knnth. 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^^-3y^ 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, 6^-18' high : spike- 

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

 spreading rays: spikelets 4-11-flowered, 25''''-6'''' long : scales strongly 

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

 not common. May-September. 



12. C. Bushii Britton. Culms l°-2.}° high : umbel 2-9-rayed, the 

 spikelets in loose, ovoid spikes : spikelets loosely 6-12-flowered, ¥^-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 thiee 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 bj' a 3-leaved invo- 

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



1. K. pumlla Michx. A densely tufted annual, 2^-10' high with usu- 

 ally 3-lobed heads of spikelets, 3^^-4^^ long: spikelets ll^^ 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'-3i^ long, 2^^ 

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

 bluffs about three miles west of Sibley. 



