236 CYPERACEAE. 
2. Cyperus diandrus Torr. Low Cyperus. (Fig. 544.) 
Cyperus diandrus Torr, Cat. Pl. N. Y. 90. 1819. 
j Cyperus diandrus elongatus Britton, Bull. Torr. Club, 
ek 19: 226. 1892 
Wy. Ss Annual, culms tufted, slender, 2/-15’ tall. Leaves 
NV EZ 4) wi j 
225° about 1/’ wide, those of the involucre usually 3, 
| “. the longer much exceeding the spikelets; clusters 
sessile and terminal, or at the ends of 1-3 rays; 
Y 
Aes spikelets 4’’-9’’ long, linear-oblong, acute, flat, 
) many-flowered; scales ovate, green, brown, or 
with brown margins, obtuse, 1-nerved, appressed, 
| membranous, dull; stamens 2 or 3; style 2-cleft, 
its branches much exserted; achene lenticular, 
oblong, subacute, gray, not shining, one-half as 
Ye long as the scale, its superficial cells quadrate, 
about as long as wide. 
In marshy places New Brunswick to Minnesota, 
xX south to South Carolina and Kansas. Aug.—Oct. 
NES The var. elonga/us is only a form with longer spike- 
lets, found in southern New York and New Jersey. 
3. Cyperus rivularis Kunth. Shining 
Cyperus. (Fig. 545.) 
Cyperus rivularis Kunth, Enum, 2:6, 1837. 
Cyperus diandrus var. (?) castaneus Torr. Ann. Lyc. 
N. Y. 3: 252. 1836. Not C. castaneus Willd. 1798. 
a7 
Similar to the preceding species, culms slender, 
tufted, 4’-15’ tall. Umbel usually simple; spikelets 
linear or linear-oblong, acutish, 4’/—10’’ long; scales 
green or dark brown or with brown margins, 
appressed, firm, subcoriaceous, shining, obtuse; 
“stamens mostly 3; style 2-cleft, scarcely exserted; 
achene oblong or oblong-obovyate, lenticular, some- 
what pointed, dull, its superficial cells quadrate. 
In wet soil, especially along streams and ponds, 
Maine to southern Ontario and Michigan, south to 
Virginia and Missouri. Aug.—Oct. 
4. Cyperus Nuttallii Eddy. Nuttall’s Cyperus. (Fig. 546.) 
4) / 2 : 
N lf; Vi bh A Creeres Nuttallii Eddy; Spreng. Neue Entd. 1: 240. 
‘ ais} 1520. 
Annual, culms slender, tufted, 4’—18/ tall, equal- 
ling or often longerthan the leaves. Leaves of the 
involucre 3-5, spreading, the larger often 5’ long; 
umbel simple or slightly compound, 3-7-rayed; 
spikelets rather loosely clustered, linear, very acute, 
flat, spreading, '/-1 4’ long, 1/’-14’’ wide; scales 
yellowish-brown with a green keel, oblong, acute, 
rather loosely spreading at maturity; stamens 2; 
style 2-cleft, its branches somewhat exserted; achene 
lenticular, narrowly obovate, obtuse or truncate, 
dull, light brown, one-third to one-half as long as 
the scale, its superficial cells quadrate. 
Salt marshes, Maine to Mississippi. Aug.—Oct. 
