168 CYPERACEAE 
umbel, sometimes becoming 6 dm. long: umbel mostly compound, of 3-12 rays varying 
from 1-20 em. in length, with 1 or more spikes sessile in the involucre: spikelets numer- 
ous, ovate, 6-14 mm. long, acutish, many-flowered : scales oblong-ovate, fully 2 mm. long, 
red-brown, pinched at the ends. 
In sandy soil, North Carolina to Florida, and California, and in Mexieo and Central America. 
Spring to fall. 
26. Cyperus pseudovégetus Steud.  Perennial by thickened tuber-like joints of 
the rootstocks.  Leaf-blades 2-6 mm. wide, smooth, nodulose, the midvein prominent: 
scapes rather stout, 3-13 dm. high, often equalled by the leaves: bracts of the involucre 
4-6, spreading : umbel several-rayed, compound : spikelets ovate, flat, many-flowered, light 
green, densely capitate, 4-6 mm. long : scales keeled, conduplicate, 1-nerved, curved, acute: 
stigmas 3 : achene linear, 3-angled, slightly stalked. [C. calcaratus Nees. ] 
In marshes, Delaware to Kansas, Florida and Texas. Summer and fall. 
27. Cyperus Surinaménsis Rottb. Perennial, pale green. Leaves overtopped by 
the scape ; blades mostly 1.5-4 mm. wide, usually rough along the margins: scapes slen- 
der, solitary or tufted, 2-12 dm. tall, naked and rough above: bracts of the involucre 
usually 3-5, one or all longer than the rays of the umbel, rough-margined : umbels mostly 
compound, of generally 8-12 rays of various lengths, several spikes sessile or clustered in 
the involucre: spikelets oblong or linear-oblong, 5-12 mm. long, yellow, blunt, 40-50- 
flowered, sometimes densely clustered: scales ovate, nearly 1.5 mm. long, deciduous in 
age: achenes 3-angled, oblong, about 0.8 mm. long, brown, pinched at both ends. 
In sandy swamps, Florida to Texas, and throughout tropical America. Spring to fall. 
28. Cyperus refléxus Vahl. Perennial, bright green. Leaves overtopped by the 
scape ; blades 1-4 mm. broad, smooth: scapes often tufted, slender, 1-7 dm. tall, smooth : 
bracts of the involucre 3-5, one or more surpassing the umbel, often compound, of 2-5- 
rays and one or more spikes sessile in the involucre or capitate: spikelets ovate or ovate- 
lanceolate, 4-6 mm. long, red or reddish brown, 20-25-flowered ; scales ovate, about 1.5 
mm. long, acute, imbricated : achenes 3-angled, elliptic, barely 1 mm. long, pinched at 
the base, short-beaked. 
In sandy soil, Texas. Also in tropical America. Spring to fall. 
29. Cyperus Iria L. Annual, bright green. Leaves mostly overtopped by the 
scape ; blades 2-4 mm. wide, revolute, striate: scapes erect, sometimes tufted, 2-5 dm. 
tall, smooth: bracts of the involucre usually 5, the longer ones surpassing the umbel, 
curved : umbel of 5-9 rays of various lengths, compound : spikelets narrowly oblong, 5-10 
mm. long, yellowish or brownish, numerous, 12-26-flowered, rather lax: scales obovate or 
nearly orbicular, fully 1 mm. long, thin, mucronulate, deciduous at maturity: achenes 
sharply 3-angled, oblong-obovoid, about 1 mm. long, reddish, minutely apiculate, slightly 
surpassing the scales. 
Inswamps mostly near the coast and rice fields, North Carolina to Floridaand Texas. Naturalized 
from the tropics. Spring to fall. 
30. Cyperus distans L. Perennial, bright green. Leaves often overtopping the 
scape; blades 5-12 mm. wide, striate: scapes 3-15 dm. tall, erect, smooth, not jointed : 
bracts of the involucre 5, the longer ones surpassing the umbel, ascending, spreading : 
umbels compound, of several slender rays and one or more spikes sessile in the involucre : 
spikelets numerous, very slender, linear-filiform, 1-2.5 cm. long, chestnut-colored, spicate 
and rather loosely disposed : scales oblong, fully 2 mm. long, blunt, sharply keeled : achenes 
3-angled, narrowly oblong-obovoid, 1.5 mm. long, abruptly pointed. : 
. In swampy grounds or wet woods, North Carolina and Georgia. Widely distributed in the tropics. 
Spring to fall. 
S1 Cyperus cephalánthus Torr. & Hook. Perennial, bright green. Leaves over- 
topped by the scape ; blades mostly 5-8 mm. wide, rough on the margins and the nerves 
beneath: scapes erect, 6-15 dm. tall, rough on the angles near the top: bracts of the in- 
voluere often 4 or 5, several much elongated and surpassing the umbel, drooping in age: 
umbel of 4-7 rays and one or more spikes sessile in the involucre : spikelets linear or oblong- 
linear, numerous and densely capitate, 6-10 mm. long, light chestnut-colored, scales oval- 
elliptie, 3 mm. long, acute, with several sharp ribs along the back, loosely imbricated, 
deciduous: achenes 3-angled, elliptic or obovoid-elliptic, barely 1.5 mm. long, rather ab- 
ruptly pointed. 
In low grounds, Louisiana and Texas. Spring to fall. 
32. Cyperus Háspan L. Perennial by short rootstocks. Leaves reduced to mem- 
branous acuminate sheaths: scapes weak, tufted, 3-10 dm. high: bracts of the involucre 
about 2, usually less than 2 mm. wide : umbel simple or compound, the longer rays 2-5 
em. long: spikelets few, capitate, linear, acute, many-flowered, 6-12 mm. long, about 1 
mm. wide: scales oblong or oblong-lanceolate, reddish brown, acute, mucronulate, keeled, 
