504 CTPERACE^. (sedge pamily.) 



sliaped persistent style, and somewhat margined; culm 4' -9' high : leaves flat. 

 ® — Inundated places, Rhode Island and Plymouth, Massachusetts. July. 



11. DICHROITIEIVA, Richard. Dichkomena. 



Spikes terete, flattened, aggregated in a, terminal leafy involucrate head, 

 many-flowered; some of the flowers imperfect. Perianth none. Stamens 3. 

 Style 2-cleft. Achenium lenticular, wrinkled transversely, crowned with the 

 broad tubercled base of the style. — Culms leafy, from creeping rootstocks ; the 

 leaves of the involucre mostly white at the base (whence the name, from Sir, 

 double, and xpafMi, color). 



1. D. Icucocepliala, Michx. Culm triangular ; leaves nan-ow ; invo- 

 lucre 5-7-leaved; achenium truncate, not margined. IJ. — Damp pine ban-ens 

 of New Jersey to Virginia and southward. August. 



12. CEKATOSCH«fe«fUS, Nees. Hobned Rdsh. 



Spikes spindle-shaped, producing 1 perfect and 1 to 4 staminato flowers. 

 Scales few and loosely imbricated; the lower ones empty. Perianth of 5-6 

 rigid or cartilaginous flattened bristles, which are somewhat dilated or united 

 at the base. Staancns 3. Style simple, entirely hardening in fruit into a long 

 and slender awl-shaped upwardly roughened beak with a narrow base, much ex- 

 serted, and several times longer than the flat and smooth obovate achenium. — 

 Perennials, with triangular leafy culms, and large spikes clustered in simple or 

 compound terminal and axillary cymes. (Name composed of xtpar , o horn, and 

 a-xolvos, a rush.) » 



1. C. cornicntata, Nees. Q/mes decompound, diffuse ; Im'stlcs md-shaped, 

 stout, unequal, shorter than the achenium. — Wet places, Penn. to Illinois, and 

 southward. August. — Culm 3° - 6° high. Leaves J' wide. Fruit with the 

 taper beak 1 ' long. 



2. C. macrostsichya, Gray. Cymes somewhat simple, small, the spikes 

 closely clustered ; bristles capillary, twice the length of the achenium. — Borders of 

 ponds, E. Massachusetts, Rhode Island, New Jersey, and rare southward. 

 ( Some states occur intermediate between this and the last.) 



13. RHYNCHOSPORA, Vahl. Beak-Rush. 



Spikes ovate, few - several-flowered ; the lower of the loosely imbricated 

 scales empty, the tippei-most usually with imperfect flowers. Perianth of 6 (or 

 rarely more) bristles. Stamens mostly 3. Style 2-cleft. Achenium Icnticuhir 

 or globular, crowned with the dilated and persistent base of the style (tubercle). 

 — Perennials, with more or less triangular and leafy culms ; the small spikes in 

 terminal and axillary clusters, cymes, or heads : flowering in summer. (Name 

 composed of pvyxos. a snout, and a-rropd, a seed, from the beaked achenium.) 

 * Achenium transversely wrinkled, more or less flattened, bristles upwardly denticulate. 



1. R. cyisiosa, Nutt. Culm triangular; leaves linear {^ wide); cymes 

 corymbose ; the spikes crowded and dustei-ed; achenium romid-obocale, twice the 



