CYPEEACEAE. 47 



Spikelet-clusters sessile or nearly so : achene gla- 

 brous. 2. fif. reticularis. 

 Spikelet-clusters, at least the lower ones, filiform- 



peduncled : achene pubescent. 3. S. setacca. 



Achene papillose. 4. 8. pauriflora. 



Inflorescence interruptedly glomerate-spicate. 5. S. verticillata. 



1. S. triglomerata Michx. Perennial. Stems 4-10 dm. tall: leaf -blades flat, 

 glabrous or nearly so, roughish, 3-9 mm. wide: spikelets terminal, and usually 

 also 1 or 2 lower peduncled ones: achenes ovoicl or ovoid-globose, above the 

 hypogynium, obtuse, bony, smooth, bright-white, shining, 2-3 mm. high ; hypogy- 

 nium low, papillose-crustaceous. — S. Rather rare, in woods and swainps. — 

 Schists, serpentine. — Sum. 



2. S. reticularis Michx. Perennial. Stems 3-6 dm. tall: leaf -blades narrowly 

 linear, glabrous or nearly so, 2-3 mm. wide: spikelets in a terminal cluster and 

 also in 1-3 remote axillary sessile or nearly sessile clusters: achenes globose, 

 dull-white, reticulate, 1 mm. in diameter, glabrous. — S. Rare, in swamps. — 

 Serpentine. — Sum. 



3. S. setacea Poir. Perennial. Stems spreading or diffuse, 3-6 dm. long: 

 leaf -blades linear, nearly flat, glabrous, 3-8 mm. wide: spikelets in a loose 

 terminal cluster, and also in 1-3 filiform-stalked drooping axillary ones: achenes 

 globose above the hypogynium, somewhat pointed, 2-2. .5 mm. in diameter, irreg- 

 ularly rugose-reticulate with low ridges, the ridges pubescent. — S. Rare in 

 low grounds. — Schists. — Sum. 



4. S. pauciflora Muhl. Perennial, pubescent. Stems slender, usually tufted, 

 2-5 dm. tall: leaf -blades narrowly linear, less than 2 mm. vsdde, the upper 

 elongate and often overtopping the stem: spikelets in a small terminal cluster 

 and also in 1 or 2 axillary ones: achenes globular, 1.5-2 mm. in diameter, 

 papillose, the lower papillae elongate and reflexed : hypogynium obtusely tri- 

 angular, supporting 6 distinct tubercles. ■ — S. Rather rare, in dry soil. — 

 Schists, serpentine. — Sum. 



5. S. verticillata Muhl. Annual. Stems very slender or filiform, 1-5 dm. 

 tall: leaf-blades very narrowly linear, 0.5-1 mm. wide, erect, weak, shorter 

 than the stem: spikelets in several separated clusters: achenes globose, fully 

 1 mm. in diameter, with sliort transverse ridges or somewhat reticulate: 

 hypogynium none. — M. Rare, in swamps. — Limestones. — Sum. and fall. 



11. CAKEX L.^ Perennial grass-like herbs. Culms (stems or scapes) 

 mostly 3-angled and tufted. Leaves 3-ranked. Bracts elongate or very short, 

 subtending the spikes, or wanting. Flowers monoecious or dioecious, solitary 

 in the axils of small bracts (scales). Spikes either wholly pistillate, wholly 

 staminate, or sometimes bearing both staminate and pistillate flowers. Peri- 

 anth wanting. Staminate flowers of 3 stamens: filaments filiform. Pistillate 

 flowers of a single pistil with a style and 2 or 3 stigmas, borne on a very short 

 axis in the axil of a sac-like bractlet or second bract called the perigynium 

 (utricle), which completely encloses the achene. Achene 3-angled or lenticular. 

 — Sedge. 



A. Achenes lenticular and stigmas 2 : lateral spikes sessile ; terminal spike partly 

 pistillate, or if staminate, the lateral spikes short or heads dioecious. Vignea. 

 Spikes always with staminate flowers at apex. 



Perigynia 2-5 mm. long, the beak not exceeding the body. 



Spikes usually ten or less, green or reddish-brown tinged : sheaths loose, or 

 if tight neither red-dotted nor transversely rugulose. I. Muhlenbergianae. 

 Spikes numerous, yellow or brown : sheaths 

 tight, the opaque part either red-dotted 

 or transversely rugulose. 



' Contributed by Mr. Kenneth K. Mackenzie. 



