504 CYPERACEJE. (SEDGE FAMILY.) 



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

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



11. I> 1C II ROM EN A, Richard. DICHROMENA. 



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 Si's, 

 double, and xpo>/u.a, color). 



1. I>. leucocepliala, Michx. Culm triangular ; leaves narrow ; invo- 

 lucre 5-7-leaved; achenium truncate, not margined. 1J. Damp pine barrens 

 of New Jersey to Virginia and southward. August. 



12. CERATOSCH<ENUS, Nees. HORNED RUSH. 



Spikes spindle-shaped, producing 1 perfect and 1 to 4 staminate 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. Stamens 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 /ce'pas, a horn, and 

 a 'xoivos , a rush.) 



1. C. comic ill ata, Nees. Cymes decompound, diffuse ; bristles awl-shaped, 

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

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

 taper beak 1' long. 



2. C. macrostachya, 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 uppermost usually with imperfect flowers. Perianth of 6 (01 

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

 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 pvyxpSi a snout, and tnropa, a seed, from the beaked achenium.) 

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



1. R. cymosa, Nutt. Culm triangular; leaves linear (y wide); cymes 

 corymbose; the spikes crowded and clustered; achenium round-obovate, twice the 



