576 cyperacejE. (sedge family.) 



differs in its flaccid culm, transversely wrinkled sheaths, orbicular achenium, 

 &c.) — Ohio to Illinois and Kentucky. 



19. C. alopecoidea, Tuckcrman. Head of 8-12 aggregated spikes, 

 oblong, dense ; perigynia compressed, nerveless or very obscurely nerved, ovate from 

 a broad truncate or somewhat heart-shaped base, a little longer than the scale ; 

 achenium pyriform; base of the style not tumid. (C. cephalophora, var. maxima, 

 Dew. ) — Woods, W. New York to Penn., Michigan, &c. — Resembles the last, 

 but smaller, with shorter and more compact spikes ; easily distinguished by the 

 nearly nerveless perigynia, and the different achenium and style. 



20. C. murieata, L. Spikes 4-6, ovoid, approximate but distinct, the 

 lowermost sometimes a little remote; perigynia ovate-lanceolate, somewhat com- 

 pressed, nerveless, or very obscurely nerved towards the base, rather longer than the 

 scale; achenium ovate; base of the style not tumid.. — Fields, Massachusetts 

 (introduced?), Ohio, and Kentucky: rare. — Spikes mostly looser than in the 

 last, the perigynia narrower, with a longer and more tapering beak. (Eii.) 



* * * * Perigynia sessile, plano-convex, compressed, more or less margined, mem- 

 branaceous, with a rather short and rough (or wholly smooth in No. 26) 

 2-toothed beak, spreading and green at maturity : scales of the fertile spikes 

 tawny or white : bracts bristle-shaped, commonly shorter than the culm. — 

 MuhlenbergiXn^e. 



21. C. sparganioides, Muhl. Spikes 6-12, ovoid; the upper ones aggre- 

 gated, the lower distinct and more or less distant ; perigynia broadly-ovate, nerveless, 

 rough on the narrow margin, about twice the length of the ovate-pointed scale ; 

 achenium roundish-ovate; style short, merely tumid at the base. — Var. minor, 

 Boott, is merely a reduced form. (C. cephalophora, var. Torr. C. murieata, 

 var. cephaloidea, Dew. 0. cephaloidea, Dew. in part.) — Low rich grounds. — 

 A robust species, with rather wide pale-green leaves; sometimes with 1-2 short 

 branches of a few spikes each at the base of the compound spike (probably C. 

 divulsa, Pursh, not of Goodenough). 



22. C. cephaloidea, Dew. (in part), Boott. Spikes 5 or 6, contiguous; 

 the broadly ovate perigynia wing -margined, spongy at the base, shorter beaked, 

 equalling or shorter than the cuspidate-tipped scale; style bulbous at the base. — 

 New York ? Illinois (Yasey). — Much resembles and has been confounded with 

 the small form of the foregoing. 



23. C. Cephalophora, Muhl. Spikes 5-6, small, and densely aggregated 

 in a short ovoid head ; perigynia broadly ovate, with 3-4 indistinct nerves on the outer 

 side, scarcely longer than the ovate roughly-pointed scale ; achenium and style 

 as in the last. (C. cephaloidea, Dew. (in part.) — Var. angustifolia, Boott, 

 is a narrow-leaved, smaller form. (C. Leavcnworthii, Dew.) — Woods and 

 fields : common. 



24. C. Muhlenbergii, Schk. Spikes 3-9, closely approximate, forming 

 an oblong head ,• perigynia orbicular-ovate, with a very short beak, prominently many- 

 nerved on both sides, about the length of the ovate roughly-pointed scale; ache- 

 nium orbicular, with a very short bulbous style. — Fields : rather common, especially 

 southward. — Culms 12' -18' high, and with the leaves pale and rigid: com- 

 monly with a bract to each spike. 



