Cyperaceae 75 
AA. Scales not spreading or only at the tipe, very little longer than the akenes, C. (A. 
subsquarrosa. ) H. micrantha Brit. 
CYPERUS 
Stems mostly 3-angled, simple, leafy at base, with | or more leaves at the summit 
forming an involucre to the inflorescence. Peduncles or rays unequal, sheathed at base. 
Spikelets few- to many-flowered, mostly flat, variously arranged but ours again grouped 
in head-like clusters or radiating spikes; scales 2-ranked, deciduous when old. Stamens 
I—3. Style 2—3-cleft, deciduous. Akene lens-shaped or 3-angled, naked at apex. 
Ours in moist and sandy soil. (Kupeiros—the ancient Greek name for these plants. ) 
A. Leaves other than those of the involucre 2 mm. or less wide; spikelets in head-like 
clusters. 
B. Annual; spikelets 4—8 mm. long; persistent but the scales falling from the axis 
at maturity; scales 3—-7-veined; stamen |. 
€. Scales tapering to slender recurved tips; plants 2.515 cm. high; akene 
widest at the top. C. E. 
C. inflexus Muhl. (Awned Cyperus) 
CC. Scales acute but without recurved tips; plants 7.5—-38 cm. high; akene 
widest at the middle. E. 
C. acuminatus T. & H. 
BB. Perennial; spikelets 8—17 mm. long, the whole spikelet dropping off at ma- 
turity; scales 9—]3-veined; stamens 3. E. 
C. houghtoni Torr. 
AA. Leaves other than those of the involucre 3-8 mm. wide; spikelets grouped in 
radiating spikes. 
D. -Leaves all linear, with blade; scales falling from persistent spikelet-axis at 
maturity; akene less than 3 times as long as thick. 
E. Wings of spikelet-axis persistent; spikelet 3 mm. wide; scales straw-color 
or yellowish-brown; akene obtuse at apex. E. 
C. esculentus L. (Yellow Nut-grass) 
EE. Wings of spikelet-axis separating from it as 2 anterior scales: spikelet less 
than 2 mm. wide; scales bright chestnut-brown; akene pointed at apex. W. E. 
C. erythrorhizos Muhl. (Red-rooted Cyperus) 
DD. Leaves at base reduced to mere sheaths; whole spikelet dropping off at ma- 
turity; akene 3—4 times as long as thick. C. 
C. strigosus L. (Straw-colored Cyperus) 
DULICHIUM 
Perennial, tall; stems terete, hollow, jointed, leafy to the top. Lower leaves re- 
duced to sheaths. Spikes axillary, peduncled, simple or compound. Spikelets 2- 
ranked, flat, linear, many-flowered; scales 2-ranked, keeled, folded lengthwise, decurrent 
on the joint below. Flowers perfect. Perianth of 6—29 retrorsely barbed bristles. Sta- 
mens 3. Style 2-cleft at the summit, persistent as a beak on the summit of the akene. 
Akene linear-oblong. In swamps and at borders of lakes. (Gk. duo—2, leichen—a 
scale; the scales of the spikelets are in 2 ranks.) W. (D. spathaceum.) 
D. arundinaceum Brit. (Dulichium) 
ERIOPHORUM COTTON-GRASS 
_ Perennial by rootstocks; stems erect, 3-angled or nearly terete. Leaves linear, 
1—2 of the upper reduced to'bladeless sheaths. Spikelets terminal, solitary or in heads or 
