172 CYPERACEAE 
nerved, thin: stigmas 3, much exserted : achenes narrowly linear, about 3 mm. long, ob- 
tuse, apiculate, about 5 times as long as thick, and 3 as long as the scale. 
In dry fields or woods, New Jersey to North Carolina and Missouri. Summer and fall. 
53. Cyperus dissitifldrus Torr. Perennial, bright green. Leaves somewhat overtop: 
ping the scape, smooth or nearly so: scapes sometimes sparingly tufted, very slender, 
3-angled, smooth: bracts of the involucre mostly 4-6, the longer ones surpassing the 
umbel: umbel;of 3-5 slender rays and one or more spikes sessile in the involucre: 
spikelets linear-subulate, slender, 5-8 mm. long, spreading, 5—7-flowered, chestnut-colored, 
acute, not crowded, flattened: scales ovate to oblong, 2.5-3 mm. long, acute, closely im- 
bricated : achenes 3-angled, oblong-prismatic or slightly broadened upward, 1.5 mm. long, 
abruptly pointed. 
In sand, Florida to Texas. Spring to fall. 
54. Cyperus retrofráctus (L.) Torr. Perennial by tuber-like corms. Leaf-blades 
3-5 mm. wide: scapes usually rough-puberulent, at least above, mostly longer than the 
puberulent leaves: bracts of the involucre 4-7, the longer not greatly exceeding the umbel, 
sometimes shorter: umbel simple: rays 5-15 cm. long, their sheaths 2-toothed : heads 
oblong or obovoid: spikelets linear-subulate, 6-12 mm. long, about 1 mm. thick, 1-2- 
flowered, all soon strongly reflexed: flowering scales lanceolate, acute, the upper one 
subulate, all strongly several-nerved: stigmas 3: achenes linear, 1.5-2 mm. long, 3- 
angled, obtuse, apiculate, 3 as long as the scale. 
In sandy soil, southern New Jersey to Florida, Kentucky, Arkansas and Texas. Summer and fall. 
55. Cyperus ovularis ( Michx.) Torr. Perennial by hard tuber-like corms. Leaves 
smooth ; blades 4-6 mm. wide: scape usually strict, smooth, 2-8 dm. tall, longer than the 
leaves : longer bracts of the involucre much exceeding the umbel : umbel simple, few-rayed; 
sheath of the rays truncate or slightly toothed : spikes globose, 8-14 mm. in diameter, very 
dense, the spikelets radiating in all directions : spikelets 4-7 mm. long, usually 3-flowered : 
scales ovate or ovate-lanceolate, obtuse or subacute, green, strongly several-nerved : stigmas 
3: achenes linear-oblong, 3-angled, about 1.5 mm. long, 1-3 times as long as thick. 
In dry fields and on hills, southern New York to Florida, Illinois, Kansas and Texas.—C. ovularis 
sphaéricus Boeckl., differs in its usually smaller heads, the spikelets more subulate, reddish brown. 
Arkansas to Texas. Summer and fall. 
56. Cyperus retrórsus Chapm.  Perennial, pale green. Leaves overtopped by the 
scape; blades 3-5 mm. wide, sometimes with rough margins and nerves beneath : scapes 
erect, 4-7 dm. tall, smooth : bracts of the involucre 7-10, mostly surpassing the umbel : 
umbel simple, of usually 8 slender rays: spikes narrowly obovoid, 1-1.5 cm. long: spike- 
lets densely crowded, subulate, 3 mm. long, the lower ones becoming reflexed : scales ob- 
long or nearly so, 2.5-3 mm. long, ribbed, closely appressed : achenes 3-angled, oblong- 
prismatic, nearly 2 mm. long, light brown. [C. retroversus Chapm.] 
On the sandy shore of Caximbas Bay, Florida. Spring to winter. 
57. Cyperus cylíndricus (Ell.) Britton. Perennial by hard corms. Leaf-blades 
2-3 mm. wide : scapes smooth, usually tufted, 1-5 dm. tall, longer than the leaves: longer 
bracts of the involucre much exceeding the umbel : umbel simple, the rays short, or the 
longer 2-7 cm. long, the sheaths 2-toothed: spikes very dense, cylindric, 5-15 mm. long, 
4-8 mm. in diameter, simple : spikelets 3-4 mm. long, flattish, 1-2-flowered, spreading or 
the lower reflexed : scales green, oblong : rachis winged : stigmas 3: achenes linear-oblong 
about 1.5 mm. long, 3-angled, granular, apiculate, slightly more than 4 as long as the scale 
In sandy soil and on the sea shore, southern New York to Florida and Texas. Summer and fall. 
58. Cyperus Plankii Britton. Similar to C. cylindricus in habit, but stouter. Leaf- 
blades mostly 2.5-4 mm. wide, smooth : scapes solitary or sparingly tufted, 3-10 dm. tall, 
smooth, often surpassing the leaves : bracts of the involucre broader than the leaf-blades, 
sometimes 6-7 mm. broad, the longer ones surpassing the umbel : umbel simple, of 4-10 
rays, the larger 5-15 cm. long, mostly ascending: spikes very dense, cylindric, 15-20 mm. 
long, 10-15 mm. in diameter, green : spikelets 5-7 mm. long, 3-4 flowered : scales ribbed : 
rachis winged : stigmas 3: aghenes linear-oblong, 1.5 mm. long, 3-angled, coarsely granu- 
lar, apiculate. i 
On plains and prairies, Oklahoma, the Indian Territory and Texas. Spring to fall. 
59. Cyperus cylindrostachys Boeckl. Perennial, pale green. Leaves overtopped 
by the scape ; blades 4-8 mm. wide, smooth : scapes often sparingly tufted, 3-15 dm. tall, 
3-angled, smooth : bracts of the involucre 5-8, the longer ones much surpassing the umbel : 
umbel simple or compound, of 6-12 slender rays and one or more spikes sessile in the in- 
volucre : spikes cylindric, 1.5-3.5 cm. long, mostly less than 1 cm. thick, usually com- 
pound : spikelets subulate, 4-5 mm. long, grayish brown or tinged with yellow, numerous, 
densely crowded, spreading or recurved : scales oblong or nearly so, 2.5-3 mm. long, blunt, 
