460 
+ + Style not bulbous at base. 
+ Flowers without inner scales, but bristles weneraily present, 
7. Scirpus. Spikelets solitary or clustered, or in a compound umbel, the stem 
often leafy at base and inflorescence involucrate: barbed bristles 3 to & or none: 
stamens mostly 3. 
++ ++ Flower with one or more inner scales, 
8. Puirena. Seales of spikelet awned below apex: flower surrounded by 3 stalked 
petal-like scales alternating with 3 bristles, 
9. Hemicarpha. llower with a single very minute hyaline seale next the axis of 
the spikelet: bristles none, 
Tribe II. Spikelets mostly 1 or 2-flowered (sometimes more in No. 10), generally 
with 2 to many of the lower scales empty.—RHYNCHOSPORE.E. 
10. Rhynchospora. Spikelets terete or tlattish; scales convex, either loosely en- 
wrapping or regularly imbricated: achene crowned with a persistent tuberele or 
beak, and commonly surrounded by bristles, 
11, Cladium. Spikelets terete, few-tlowered, the scales, ete., as in the preceding: 
achene destitute of tuberele: no bristles. 
II. Flowers Unisexual. 
Tribe II, Flowers monecious, the two kinds in the same or in different spikes: 
achene naked, bony or erustaceous, supported on a hardened disk.—NScCLERIE.E, 
Scleria. Spikes few-tlowered; lower scales empty: no bristles or inner scales. 
Tribe 1V. Flowers moneecious in the same (androgynous) or in separate spikes, or 
sometimes dicecious: achene inclosed in a sac (perigynium).—CARICE®. 
Carex. Hypogynous bristle short and enclosed in the perigynium or none, 
1. CYPERUS L. 
Stems mostly triangular and simple, leafy at base and with one or 
more leaves at summit forming an involuere to the umbel or head, 
with few to many-tlowered mostly flat spikelets, unequal peduncles or 
‘ays sheathed at base, 2-ranked conduplicate and keeled seales, 1 to 3 
stamens, no bristles or inner scales, 2 or 3-cleft deciduous style, and a 
lenticular or triangular achene naked at apex. 
§ 7. Aehene lenticular, the edge turned to the rhachis, which is narrow and not winged: 
spikelet flattened, many-flowered: annuals,—PYCREUS. 
* Umbel simple or capitate, rarely slightly compound, 
+ Superficial cells of achenium oblong. 
1. C. flavescens L. Stems 10 to 25 em. high: involucre 3-leaved, very unequal: 
spikelets 10 to 16 mm, long, becoming linear, obtuse, clustered on the 2 to 4 very 
short rays: scales obtuse, straw-yellow: stamens 3: achene shining, orbicular.—In 
low ground, extending from Canada to Texas and northern Mexico. 
+ + Superficial cells of achenium quadrate, 
2. C, diandrus Torr. Spikelets 6 to 18 mm. long, lance-oblong, scattered or 
clustered on the 2 to 5 very short or unequal rays: scales rather obtuse, purple- 
brown on the margins or nearly all over: stamens 2 or sometimes 3: achene dull, ob- 
long-obovate,—Extending throughout eastern North America and as far west as 
New Mexico. Var. Carrrarus Britton, extending from Texas (Sabine Pass and 
