CYPERACEAE .167 
11. ERIOPHORUM L. Perennial erect caulescent herbs with rootstocks. 
Leaves with narrow blades, or some of them mere bladeless sheaths. Spikelets 
solitary, clustered, or umbellate, often subtended by an involucre of 1 to sev- 
eral bracts. Scales spirally imbricate, usually all fructiferous, or some of the 
lower ones empty. owers perfect. Perianth of numerous naked capillary 
ciate y ode bristles. Stamens 1-3. Style not swollen, deciduous. Stig- 
s 3. Ae angled.—About 15 species, in the northern hemisphere.— 
un e ee ee COTTONRUSHES. 
' Spikelets peduncled; scales oy 1-ribbed, the rib e to the apex 
achene obovoid, rounded at the ap 1. iidicarimatum. 
Spikelets glomerate; scales prominently striate ribbed, the 
ribs not extending to the apex: achene oblong-obo void, ab- MM 
ruptly pointed. 2. E. virginicum. 
1. E. viridicarinatum (Engelm.) Fernald. Stem 3-9 dm. tall: leaf-blades 
flat below bed channeled tip: bracts of the involucre neither spreading nor 
deflexed: spikelets several or mumerou ES 
drooping on ipee pn M e. 
ape broadly o acute 
or acutish: ae dms e dicrum 
ie obovoid, 2.5-3 mm. long, rounded 
at the apex, not stipitate.—( HARE-TAIL. 
T COTTON-GRAS S 
Ga. to B. C., Mich., and Newf. Former! 
included in E. polystachyon L. 
E. virginicum L. Stem 4-12 dm tall: 
: "i pus eae _below the channeled tip: 
bracts of nvolucre spreading or de- 
fle oe spikelets P in i dense. terminal 
eluster: scales ovate, md . lon ng, obtuse 
perianth- “bristles brown Ren ellipso oid. 
obovoid, 3.5—4 m oues ab ruptly narrowed at the apex, short-beaked, dap 
—( TA Ec. n id bogs and swamps, various provinees, Fla. 
Nebr., Man., Ont., and N 
12. SCIRPUS L. Annual or perennial, scapose or caulescent edis 
Leaves with blades or represented by mere sheaths. Spikelets few- to many- 
flowered, terete or somewhat flattened, solitary, capitate, or beste usually 
involucrate, the involucre, when simple, appearing like a continuation of the 
cales spirally imbricate. Flowers perfect. Perianth of 1-6, or 8, 
barbed or smooth, sometimes pubescent, bristles, or rarely wanting. Stamens 
2 or 3. Style not swollen, wholly deciduous or the base persistent. Stigmas 
or 3. Achene 3-angled or lenticular, beaked or beakless, not tubercled.— 
About 150 species, widely distributed in cool and warm regions.—Sum.—fall, or 
all year S.—BULRUSHES.  CLUBRUSHES. 
Involucre of a a single bract, or wantin ng. l 
P solitary, or rarely 2 2 in No. 5, terminal. I. CAESPITOSI. 
Spikelets more than 1, usually several or many, often ap- 
parently lateral. . II. VALIDI. 
Involucre of 2 or more bracts with flat blades. 
Spikelets not in dense globose heads. III. SYLVATICI. 
Spikelets very numerous in one or several dense globular 
heads. IV. CUBENSES. 
