164 



CYPERACEAE 



39. 

 40. 

 41. 



C. erythrorhizos. 

 C. digitalus. 

 C. Halei. 



B. 



42. C. Floridanus. 



43. C. Engelmannii. 



44. 



45. 



46. 

 47. 



C speciosus. 

 C. ferax. 



C. Eggersii. 

 C. oxycarioides. 



48. C. Martindalei. 



49. C. setigerus. 



50. 

 51. 



52. 

 53. 



C. strigosus. 

 C. stenolepis. 



C. refractus. 

 C. dissitiflorus 



54. C. retrofractus. 



55. C. ovularis. 



56. C. retrorsus. 



Wings of the rachis separatiiie: from it as interior scales : annuals. 

 Spikes loose, or if dense not narrowly cylindric : spikelets 6-25 mm. long. 

 Spikelets crowded : scales loose. 

 Spikelets not crowded : scales closely appressed. 

 Spikes very dense, cylindric : spikelets 3-5 mm. long. 

 Rachis of the spikelets deciduous. 



Eachis breaking up into 1-fruited joints : spikelets nearly terete. 

 Spikes solitary : scapes filiform : plants perennial. 

 Spikes umbellate or capitate-congested : scapes stout to slender : 

 plants annual. 

 Scales of tlie spikelets distant : achene linear-oblong. 

 Scales of the spikelets manifestly imbricated ; achene obovoid. 

 Spikelets relatively loosely spicate. 



Spikes dull brown : scales thin, not tightly appressed. 

 Spikes yellowish or grayish brown : scales firm, appressed. 

 Spikelets densely congested into 1-4 heads. 



Inflorescence "umbellate: spikes disposed at the ends of the 2-4 



rays of the umbel. 

 Inflorescence capitate : spikes collected into a terminal con- 

 gested cluster. 

 ■Rachis deciduous above the lower pair of scales : plants perennial by hard 

 corm-like tubers. 

 Achene narrowly linear-oblong, 23/^-4 times as long as thick. 

 Spikelets distinctly liattened, several-many-llowered. 

 Spikelets in dense globular heads. 

 Spikelets loosely spicate or relatively so. 

 Spikelets chestnut-brown. 

 Spikelets yellow to yellow-brown. 

 Scales appressed. 

 Scales loose, somewhat spreading. 

 Spikelets nearly terete to a little flattened, 1-few-flowered. 

 Spikelets loosely spicate. 



Spikelets 1-2 cm. long: achene about 3 mm. long. 

 Spikelets less than 1 cm. long : achene 1.5 mm. long. 

 Spikelets capitate or capitate-spicate. 



Spikelets all reflexed : scapes almost always rough. 

 Spikelets spreading or only the lower ones reflexed : scapes 

 smooth. 

 Spikes or heads dense, cylindric to globose. 

 Spikes globose. 

 Spikes cylindric to oval or obovoid. 



Spikelets3-7 mm. long : spikesobovoid or cylindric. 

 Spikes obovoid : lower spikelets reflexed. 

 Spikes cylindric. 



Spikes 0.5-2 cm. long, simple. 



Spikelets 3—1 mm. long, 1-2-flowered. 

 Spikelets 5-7 mm. long. 3— 1-tlowered. 

 Spikes 1.5-3.5 cm. long, usually compound. 

 Spikelets 8-10 mm. long : spikes oval. 

 Spikelets loosely spicate or capitate. 

 Spikelets 8-12 mm. long, subulate. 

 Spikelets 3-5 mm. long, not subulate. 

 Achene oblong to obovoid, not more than twice as long as thick. 

 Spikelets with 1-4 achenes. 



Rachis wingless or narrowly winged. 



Umbel simple or head solitary : leaf-blades relatively narrow. 

 Spikelets loosely spicate. 

 Spikelets densely spicate or capitate. 

 Heads ovoid to cylindric. 

 Heads globose to subglobose. 



Heads dark brown : scales mucronulate. 

 Heads green or greenish brown : scales not mu- 

 cronulate. 

 Achene 2 mm. long : scales about 2 mm. long. 

 Achene 1 mm. long : scales less than 2 mm. 

 long. 

 Umbel compound : leaf-blades relatively broad. 

 Rachis- wings broad, membranous. 

 Scales firm, not appressed. 

 Scales thin, closely appressed. 

 Spikelets with 5-10 achenes. 



Heads sessile, or on rays less than 2 cm. long. 

 Heads terminating rays 2-7 cm. long. 



1. Cyperus flav6scens L. Annual, yellowi-sh green. Leaf-blades 

 smooth, the longer usually exceeding the inflorescence : scapes very slender, tufted, 7-30 

 cm. tall : spikelets in 3's-6's, linear, subacute, yellow, many-flowered, flat, 8-18 mm; long, 

 3-4 mm. broad ; the clusters terminal and sessile, or on 1-4 short rays : scales ovate, ob- 

 tuse, 1-nerved, appressed, twice as long as the achene : stigmas 2 : achenes orbicular-obo- 

 void, black, obtuse, shining, the superficial cells oblong. 



In marshy soil, Maine to Michigan, Florida and Mexico. Also in the Old World. Summer and fall . 



2. Cyperus didndnis Torr. Annual, deep green. Leaf-blades about 2 mm. wide : 

 scapes tufted, slender, 5-40 cm. tall : bracts of the involucre usually 3 : spikelets 8-18 

 mm. long, linear-oblong, acute, flat, many-flowered ; the clusters sessile and terminal or at 



57. 

 58. 

 59. 

 60. 



61. 

 62. 



63. 

 64. 

 65. 



C. cylindricus. 

 C. Plankii. 

 C. cylindrostachys. 

 C. Lancastriensis. 



C. uniflorus. 

 C. subuniflorus. 



C. tetragonus. 

 C. flavus. 

 C. fuligineits. 



66. C. fllicuhnis. 



67. 

 68. 



69. 

 70. 



71. 



7';>. 



C. Blodgettii. 

 C. ligularis. 



C. Grayi. 

 C. echinatus. 



C. brunneus. 

 C. Ottonis. 



2-3 mm. wide, 



