ORDER CXLI. CYPERACE^. 555 



ANALYSIS. 



1. Achenium inclosed in a sac (perigynium) Carex, 14 



Achenium not inclosed in a sac 2 



2. Flowers perfect 8 



Flowers not perfect Scleria. 13 



8. Flowers with bypogynous setae (bristles) 4 



Flowers without hypogynous setae 9 



4. Flowers distichous (2-rowed) Dulichium, 12 



Flowers not distichous 5 



5. Setai capillary 6 



Setae not capillary Fuirma, 7 



6. Setae consisting of numerous hairs Eriophorum, 6 



Bets of 5— many bristles 7 



7. Spikelets few-flowered ; style bifid Rhyncospora, 11 



Spikelets usually many-flowered . . 8 



S. Plants with no leaves Eleocharis, 4 



Plants with leaves Seirpus, 5 



9. Flowers distichous 10 



Flowers imbricate 12 



10. Spikes 1— 3-flowered 11 



Spikes more than 8-flowered Cyperus, 1 



11. Style bifid Kyllingia, 3 



Style trifid Mariscus, 2 



12. Stvle trifid Eleocharis, 4 



Style bifid 13 



13. Stamen 1 Isolepis, 8 



Stamens usually more than 1 14 



14. Leaves of the involucre 5 or more Dichromena, 10 



Leaves of the involucre 2—5 Firnbristylis, 9 



Tribe I.— CYPE'RE^E. 



Flowers perfect, 2-ranked. 



Gexus I.— CYPE'RUS. 3—1. 

 (From cypris, a name of Venus.) 



Spikelets compressed. Glumes imbricate, in 2 rows, each 

 generally inclosing a flower. Setce none. 



§ 1. Style trifid ; achenium compressed. 



1. C. flaves'cexs, (L.) Stem nearly terete, shining. Leaves linear, 

 sheathing the stem at the base. Umbels compound ; spikelets crowd- 

 ed, lanceolate. Stamens 3. — If. July — Oct. Wet soils. 8 — 12 in. 



2. C. rivula'eis, (Kunth.) Stem triangular, glabrous. Leaves shorter 

 than the stem, nearly glabrous. Umbels of 3 — 4 rays ; rays unequal ; 

 involucre 3-leaved, exceeding the umbel in length. Spikes 20 — 25- 

 flowered, compressed, broadly linear; scales ovate, obtuse ; stamens 2. 

 — Georgia. River banks. 



3. C. holoscri'ceus. Stem triangular, smooth, leafy at the base. 

 Leaves longer than the culm, membranaceous, flat ; margins scabrous. 

 Umbel about 10 rays; rays unequal ; involucre 6-leaved, long; spikes 



