SEDGE FAMILY. 241 
17. Cyperus esculéntus I. Yellow Nut-grass. (Fig. 559.) 
Cyperus esculentus Y,. Sp, Pl. 45. 1753. %, 3 
Cyperus phymatodes Muhl. Gram. 23. 1817. y 
Perennial by scaly horizontal tuber-bearing root- 
stocks, culm usually stout, 1°-214° tall, commonly 
shorter than the leaves. Leaves light green, 2//-4’’ 
wide, the midvein prominent; those of the in- 
volucre 3-6, the longer much exceeding the in- 
florescence; umbel 4-10-rayed, often compound; 
spikelets numerous in loose spikes, straw-color or 
yellowish-brown, flat, spreading, 6/’/-12’’ long, 
114’ wide, many-flowered; scales ovate-oblong, sub- 
acute, 3-5-nerved; rachis narrowly winged; stamens 
3; style 3-cleft; achene obovoid, obtuse, 3-angled. 
In moist fields, New Brunswick to Minnesota, south 
to Florida and Texas. Also on the Pacific Coast from 
California to Alaska, in tropical America, and widely 
distributed in the Old World. Sometimes a trouble- 
some weed. Aug.—Oct. 
Cyperus esculéntus angustispicatus Britton, Bull. Torr. 
Club, 13: 211. 1886. —— @ a 
Spikelets very slender, 1'’ wide or less. Massachusetts to South Carolina and Missouri. 
18. Cyperus erythrorhizos Muhl. Red-rooted Cyperus. (Fig. 560.) 
Cyperus erythrorhizos Muhl. Gram. 20. 1817. 
Annual, culms tufted, stout or slender, 3/—2° tall. 
Leaves 114’/-4’’ wide, rough-margined, the lower 
|| longer than or equalling the culm, those of the in- 
volucre 3-7, some of them 3-5 times as long as the 
inflorescence; umbel mostly compound, several- 
rayed; spikelets linear, subacute, 3’/—10’’ long, less 
than 1/’ wide, compressed, many-flowered, clus- 
tered in oblong, nearly or quite sessile spikes; 
scales bright chestnut brown, oblong-lanceolate, 
mucronulate, appressed, separating from the rachis 
at maturity, the membranous wings of the rachis 
separating as a pair of hyaline interior scales; sta- 
mens 3; style 3-cleft; achene sharply 3-angled, ob- 
long, pointed at both ends, pale, one-half as long 
as the scale. 
In wet soil, especially along streams, southern On- 
tario to Massachusetts and Florida, west to Missouri, 
Kansas, Texas and California. Aug.—Oct. 
Cyperus erythrorhizos var. pumilus Engelm. is a low form, not worthy of varietal rank. 
1g. Cyperus Halei Torr. Hale’s Cyperus. 
(Fig. 561.) 
Cyperus Halet Torr; Britton, Bull. Torr. Club, 13: 
213. 1886. 
Annual, culm stout, 2°-3° tall, about equalled 
by the leaves. Leaves 3/’-4/’ wide, very rough- 
margined, those of the involucre 5-8, much elong- 
ated; umbel compound, several-rayed; spikes cy- 
lindric, sessile or very nearly so, exceedingly dense, 
44/-1’ long; spikelets very numerous, linear, 14//— 
2%’’ long, %4’’ wide, spreading; scales brown, 
keeled, indistinctly 5-nerved, oblong, mucronu- 
late, separating from the rachis at maturity, the 
wings of the rachis separating as a pair of hyaline 
scales, as in the preceding species; stamens 3; 
style 3-cleft; achene 3-angled, minute. 
In swamps, southern Missouri to Tennessee, Louisi- 
ana and Florida, July-Sept. 
