466 SEDGE FAMILY. 



C. a/fernifdiius, Linn. Umbrkm,a Plant. A greenhouse aquatic from 

 Madagascar ; culms in clumps, 2°-G° tall, smootli and triangular, leafless 

 below, but bearing a leafy, many-rayed, great involucre at the top, from 

 the axils of which spring slender-peduncled small clusters of flowers. 



C. Papyrus, Linn. (Papvuus ANnyiifeRLM). Egyptian Paper Plant. 

 Sometimes grown in aquaria, not hardy N.; sends up a jointless triangular 

 stem 4°-10° high, which is terminated by a great involucre of very narrow 

 drooping or bending leaves. 



= = Bristles about the akene, which is beaked on top. 



2. DULICHIUM. Spikelets 6-10-flowered, sessile in 2 ranks on axil- 

 lary peduncles springing from the sheaths of the leaves. Perianth com- 

 posed of 6-9 barbed bristles. 



One species, D. spathdceum, Pers., in bogs and on borders of ponds, 

 remarkable in the family for having terete and hollow culms, l°-2'-' high. 



++ -»-»■ Scales not 2-ranked, the spikelet therefore terete. 



= Bristles ; culm leafy. 



3. FIMBRISTYLIS. Spikelets umbelled, the involucral leaves 2-3. 

 Small plants of either low or dry grounds, of about a half dozen species 

 in our territory. 



= = Bristles generally present ; cttlm leafy or naked. 



II Style somewhat thickened or bulbous at the base, and persistent upon the 



top of the akene. 



4. ELEOCHARIS. Spike one, and without involucre, terminating a 

 .slender, simple, leafless culm. Many species (mostly small) in moist 

 grounds and borders of ponds. 



II II Style not swollen at the base, deciduous. 



5. SCIRPUS. Spikelets generally clustered in a compound umbel. 

 Bristles (sometimes 0) barbed. IMostly tall, rush-like, leafy, common 

 plants, but in some species the stems are slender and leafless, and the 

 spike is single and terminal, thus approaching Eleocharis, but the invo- 

 lucre is present in the form of a scale or small leaf. This genus now 

 includes Isolepis, to which the slender species with a solitary terminal 

 spike, leafless and jointless culms, have been referred. 



6. ERIOPHORUM. Like Scirpus, but the bristles not barbed and 

 often becoming silky and long exserted in fruit. A few plants in bogs, 

 mostly distinguished when mature by the white, or rusty, woolly heads. 



-1- t- Spikelets only \-2-flowered, and 2 or many of the lower scales floioer- 



less. 



7. RHYNCHOSPORA. Spikelets flattish, clustered, or panicled, 

 often whitish or rusty in color. Bristles usually surrounding the 

 beaked or tubercle-topped akene. A score of critical species, mostly 

 small and slender plants, in bogs. 



8. CLADIUM. Spikelets terete. Akene not tubercled, and no bris 

 ties. A single species, C. mariscoides, Torr., l°-2'-' high, in wet 

 places, vrith small, rusty cymes of capitate spikelets. 



