CYPERACEAE 45 



base, awned from below the apex, prominently nerved. — On sand-bars 

 along the Mississippi River at Courtney. Very rare. July-October. 



9. HEMICARPHA Nees & Am. 

 Low, tufted annuals with flowers as in Scirpus, save that there is one 

 very small inconspicuous hyaline scale at the base of the ovary. Style 

 2-cleft. Stamen one. 



1. H. micrantha (Vahl.) Britton. 1^-5' high with capillary culms : 

 spikelets 2-3 together, V^-2^^ long, sessile. — Moist sandy soil along 

 rivers, especially the Missouri Eiver. Well distributed, but never com- 

 mon. June-October. 



10. SCLERIA Berg. 



Leafy perennial with triangular culms from creeping rootstocks, and 

 monoecious spikelets in terminal, or terminal and axillary clusters. Pis- 

 tillate spikelets 1-flowered, usually intermingled with the many-flowered 

 staminate ones. Style 3-cleft. Achenes ovoid to globular, white, bony 

 and crustaceous. 



1. S. triglomerata Michx. Nut Rush. 1^°-3° tall, erect but nod- 

 ding at the summit, roughish : achene ovoid-globose, very white, shining 

 and smooth, V^ high, supported on a crustaceous disk. — Occurs locally 

 in sterile places on the prairie near Oak Grove, Grand View and Lee's 

 Summit. June-July. 



11. CAREX L. Sedge. 

 Perennial sedges with mostly triangular culms, 3-ranked leaves and 

 monoecious flowers in spikes. The staminate and pistillate flowers either 

 borne in the same spikes or in different spikes. Spikes usually subtended 

 by bracts. Floral envelopes none, the staminate flowers consisting of 

 three stamens, and the pistillate of a single pistil with a bifid or a trifid 

 style. Achene triangular or lenticular, completely enclosed in a sac, 

 called the perigynium. 



Staminate flowers numerous and conspicuous, in 

 one or more terminal spikes (sometimes pis- 

 tillate at base or apex). 



Perigynia strongly beaked, the beak terminat- 

 ing in two well-developed teeth. L 



Perigynia beakless or beaked : if beaked the 

 beak not terminating in two well-developed 

 teeth. IL 



Staminate flowers few and inconspicuous, borne 

 at the base or apex of the pistillate spike. 



Staminate flowers at the summit of the spikes. IIL 



Staminate flowers at the base of the spikes. IV. 



I. 

 Perigjnia thin, noticeably inflated. 

 Perigynia C or more long. 



Pistillate spikes globose. 1. C. Asa-Grayi, 



