531 
cyperaceje. (sedge family.) 
or cymose-panicled ; spikes ovoid-oblong (2 n long) ; stamens 2; ache- 
nium minutely corrugated, very obtuse, tipped with the minute bulb 
which is more persistent than the rest of the style. © (Scirpus 
capil laris, L. Isolepis, R. S .)—Sandy fields, common, especially 
southward. August. 
lO. PSILOCARYA, Torr. Bald-rush. 
Spikes ovoid, terete, many-flowered ; the flowers all perfect. 
Scales imbricated in several ranks. Perianth none. Stamens 
usually 2. Style 2-cleft. Achenium doubly convex, more or less 
wrinkled transversely, crowned with the persistent tubercle or 
dilated base of the style. — Perennials, with leafy culms; the 
spikes in terminal and axillary cymes. (Name from y/sihos, bare , 
and Kapva , nut , alluding to the absence of bristles.) 
1. P. SCirpoideS, Torr. Spikes 20 - 30-flowered ; scales ob¬ 
long-ovate, acute, chestnut-colored; achenium obscurely wrinkled, 
beaked with the sword-shaped persistent style, and somewhat mar¬ 
gined by its decurrent dilated base. — Inundated places, Rhode Island 
to Plymouth, Massachusetts. Culm 4'- 9' high : leaves flat. 
11 . DICHRODIENA, Richard. Dichromena. 
Spikes terete, flattened, aggregated in a terminal involucrate 
head, many-flowered, some of the flowers imperfect. Perianth 
none. Stamens 3. Style 2-cleft. Achenium lenticular, wrin¬ 
kled 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 bis, 
double , and xpa>pa, color ). 
1. R. leucocepliala, Michx. Culm triangular ; leaves nar¬ 
row ; involucre 5-7-leaved; achenium truncate, crowned with a 
conical acute tubercle, not margined. — Damp Pine barrens of New 
Jersey, rare, and southward. August. 
12 . CERATOSCHCENUS, Nees. Horned Rush. 
Spikes spindle-shaped, producing one perfect and 1 to 4 stami- 
nate flowers. Scales few and loosely imbricated, the lower 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- 
