CYPEKACEAE 165 



the ends of 1-3 rays : scales ovate, green, brown, or with brown margins, obtuse, 1-nerved, 

 appressed, membranous, dull : stigmas or style-branches 2, much exserted : achenes len- 

 ticular, oblong, gray, not shining, as long as the scale, its superficial cells quadrate and 

 about as long as wide, as in the eleven following species. 



In marshy places, New Brunswick to Minnesota, South Carolina and Kansas. Summer and fall. 



3. Cyperus rivularis Kunth. Similar to the next preceding species. Scapes slender, 

 tufted : umbel usually simple : spikelets linear or linear-oblong, acutish, 8-20 mm. long : 

 scales dark green or brown, or with brown margins, appressed, firm, rather coriaceous, 

 shining, obtuse : stigmas or style-branches 2, scarcely exserted : achenes oblong or oblong- 

 obovoid, lenticular, somewhat pointed, dull. 



In wet soil, especially along streams and ponds, Maine to Ontario, Michigan, Nebraska, North 

 Carolina and Missouri. Summer and fall. 



4. Cyperus helvus Liebm. Annual. Leaves generally 2 or 4 ; blades 1-3 mm. 

 wide, smooth : scapes tufted, 1-7 dm. tall, as long as the leaves or longer : bracts of the 

 involucre narrower than the leaf-blades, surpassing the umbel, the longer ones 5-20 cm. 

 long : umbel capitate, or 2-4 rays becoming 1-3 cm. long : spikelets few, linear to linear- 

 lanceolate, 5-8 mm. long, acutish: scales straw-colored or yellowish green, ovate, obtuse, 2 

 mm. long, deciduous at maturity, 2-keeled on the back : styles 2, well united : achenes 

 lenticular, oval or oval-obovoid, 1 mm. long, brown, dull, barely as long as the scale. 



In ditches and moist grounds, Louisiana and Texas ; also through the tropics to eastern South 

 America and in the West Indies. Spring to fall. 



5. Cyperus bipartitus Torr. Annual. Leaves usually 2 at the base of the the scape ; 

 blades setaceous or filiform : scapes 5-15 cm. tall : bracts of the involucre solitary or 2, but 

 only one well developed and erect : spikelet ovate-oblong, 5-7 mm. long, rather obtuse, 

 about 14-flowered : scales ovate, obtuse, somewhat coriaceous, closely imbricated : styles 2, 

 nearly distinct : achenes lenticular, obovoid, fully 1 mm. long, obtuse. 



In sandy soil, near New Orleans, Louisiana. Summer. 



6. Cyperus Nuttallii Eddy. Annual. Scapes slender, tufted, equalling or longer 

 than the leaves : bracts of the involucre 3-5, spreading, the larger often 12 cm. long : um- 

 bel 3-7- rayed : spikelets rather loosely clustered, linear, very acute, flat, spreading, 1-3 

 cm. long, 2-3 mm. wide : scales yellowish brown except the green keel, oblong, acute : 

 stigmas 2, somewhat exserted : achenes lenticular, narrowly obovoid, obtuse or truncate, 

 dull, light brown, to as long as the scale. 



'In salt marshes, or drifting sand, coast of Maine to Florida and Mississippi. Summer and fall. 



7. Cyperus microddntus Torr. Annual. Leaf-blades about 2 mm. wide: scapes 

 very slender, tufted, sometimes 0.5-1 dm. high : bracts of the involucre much elongated : 

 umbel commonly simple, sessile, subcapitate : spikelets linear, acute, 6-18 mm. long, less 

 than 2 mm. wide, yellowish brown : scales ovate, barely 2 mm. long, acute, thin becoming 

 rather lax : stigmas 2, much exserted : achenes lenticular, linear-oblong, short-pointed, 

 light brown, $ as long as the scale. 



In wet soil, on or near the coast, Virginia and North Carolina. Summer and fall. 



8. Cyperus Gatesii Torr. Annual, bright green. Leaves often 3-6 ; blades 1-4 mm. 

 wide, or sometimes narrower or even filiform, not firm : scapes slender, tufted, 1-4 dm. 

 tall, often surpassing the leaves : bracts of the involucre 3-5, surpassing the umbel, the 

 longer ones usually 10-20 cm. long : umbel with 3-8 rays 1-5 cm. long, or rarely nearly 

 capitate : spikelets few, linear or linear-lanceolate, 6-15 mm. long, acute : scales light chest- 

 nut-brown, oblong-lanceolate, 2-2.5 mm. long, shining, striate, deciduous at maturity: 

 achenes oblong, fully 1 mm. long, grayish, abruptly apiculate, fully \ as long as the scale. 



In springy places and low grounds, Virginia to Florida and Texas. Spring to fall. 



9. Cyperus polystachyus Kottb. Annual, pale green. Leaves usually 4-8 ; blades 

 narrowly linear, 2-4 mm. wide, smooth like the scape : scapes tufted, slender, 1-9 dm. 

 tall, generally surpassing the leaves : bracts of the involucre 3-5, much longer than the 

 umbel, nearly equal in length, or one or two sometimes 1-2 dm. long : umbel capitate or 

 some of the rays becoming 1-3 cm. long : spikelets numerous, linear-lanceolate, 6-20 mm. 

 long, acute, 15-25-flowered : scales 1.5 mm. long, gray-brown or straw-colored, acute, dull, 

 deciduous at maturity : achenes lenticular, oblong, 1.2 mm. long, dull, about twice as long 

 as thick, grayish. 



In ditches and low grounds, Florida to Louisiana, and in tropical America. Spring to fall. 



10. Cyperus pumilus L. Annual, pale green. Leaves often 3-4 ; blades gradually 

 narrowed to the apex : scapes densely tufted, slender, 1-3 dm. tall, or sometimes shorter, 

 mostly as long as the leaves or longer : bracts of the involucre usually 3 or 4, 1 or 2 of 

 them much longer than the others, the longest one often 10 cm. in length : umbel much 

 shorter than the involucre, with 3-9 rays, 1-6 cm. long and a sessile cluster of spikes, or 

 sometimes all spikes sessile : spikelets linear, 4-8 mm. long, relatively few in a spike, 15- 



