OLABKE — THE OYPEBACEAE OF COSTA BICA. 447 



[nfloreecence usually more lax; spikeleta subspicately arranged, less flattened, 

 more loosely imbricated, lew polished, sometimes variegated cheetnul color and . 



Distribution: Both in Central America and In Argentina. 



Costa Rican collbctions: Volcan de Poas, altitude 2,500 meters, Tondui LO 

 (i. Pycreus elegantulus" C. B. Clarke in Dur. & Schinz, Fl. Air. 5: 536. 



Cyperus elegantulus Steud. Flora25: 583. L842. 



Cyperus dmidnus 3. S. & C. B. Presl, Rel. Haenk. 1: L66. L830 



Distribution: Quite common in Africa. Frequenl in America all the way from 

 Mexico to Soui hem Brazil. 



Costa Rican collections: E] Copey, altitude L,800 meters, Tonduz, L2335; 

 Carrillo, ( 'ooper, 599. 



This species is qoI easily distinguishable from small specimens of /'. melano- 

 8tachyus. 



SPECIES OF PYCREl S TO BE LOOKED FOR l\ COSTA RI( \. 



Pycreus polystachyus Beauv. Fl. d'Owar. 2: is. pi. 86. Jiff. :. L807. 



Distribution : In all i he warmer parts of the world I lecurs in the Wesl Indies in 

 many varieties and quite commonly; nol yel received from Costa Rica. The plant 

 resembles /'. propinquus and /'. helvus, its spikeleta reddish. 



3. CYPERUS L. 



Spikelets 5 to many-flowered; rachilla persistent; two Lowest glumes empty, the I 

 or more next succeeding disl ichous, bisexual, perfect ing nuts, deciduous from the base 



upward, a few of the uppermost glumes sterile or vacant, s swhat triserial; hypog} 



nous bristles none; stamens 1 to 3, anterior: style- branches 3; mil trigonous, tin- 

 anterior angle not rarely more or Less depressed. -Plants glabrous. Stems naked 

 except near the base, there leafy. Spikelets in digitately or Bpicately clustered spikes. 



Species 280; scattered over almost all parts of the world that are warm or temperate, 

 common in hot countries, rare in cold. 



KEl TO THE SPECIES. 



Spikelets digitate or congested. I Pycnostachyae.) 

 Annuals (here also C. haspan, no. 3j. 



Stem monocephalous; spikelets green 1. C. tenerrimus. 



Spikes umbellate, ferruginous or brownish 2. C. uncinatus. 



Perennials. 



Stamen I: plants large or of middle size. 

 Kays of the umbel short . 



Leaves transversely lineolate (i. C. virens. 



Leaves qoI transversely Lineolate. 



Spikelets much compressed 7. ('. suriruimensis. 



Spikelets turgid, congested 8. C. luzulae. 



Rays of the umbel longer than the stem it. C. simplex. 



Stamens 2 or 3; si ems bearing many spikes. 

 Spikelets 1 to 2 mm. wide; nut small. 



Glumes imbricated ;'>. C. haspan. 



< Humes distant . forming a Loose spikelel . . LI. C. chorisanthus. 

 Spikelets 2 to 3 mm. wide. 



Steins leafless. 



Plain dioecious 5. C. canus. 



Spikelets bisexual I. C. alt* rnifohus. 



Leaves present, long LO. C.diffusus. 



o The specific name dmidnus is older and unoccupied, Editor. 



