270 



CYPERACEAE 



Spikelets normally more than one, if only one, appearing as if lateral. 

 Involucre of one bract, rarely 2. 



Spikelets few, 1-12, appearing lateral. 

 Culm sharply 3-angled. 



Spikelet much shorter than the bract; scales avvned. 

 Spikelet not much shorter than the bract; scales mucronulate. 

 Culm not sharply 3-angled. 

 Spikelets several or numerous, umbeled. 

 Perianth-bristles downwardly barbed. 

 Achenes lenticular. 



Achenes nearly as long as the scales. 

 Achenes much shorter than the scales. 

 Achenes trigonous. 

 Perianth-bristles short-plumose below. 

 Involucre of 2 leaves or more. 



Spikelets several or few, large, capitate or subumbellate. 

 Achene lenticular or plano-convex. 



Scales red-brown; achene cuneate at base. 

 Scales pale brown or whitish; achene narrowed at base. 

 Achene trigonous. 

 Spikelets numerous, small, in umbeled heads or compound umbels. 

 Perianth-bristles about as long as the achene or little longer, mostly 

 Style-branches 2; achene plano-convex. 

 Style-branches 3; achene trigonous. 



Perianth-bristles stiff, downwardly barbed. 

 Perianth-bristles weak, flexuous, a little roughened. 

 Perianth-bristles much longer than the achene, smooth, entangled. 

 Bristles much longer than the scales; spikelets densely capitate. 



8. 5. americanns. 



9. S. olneyi. 



10. 5'. nevadensis. 



11. S. vaUdiis. 



12. .?. acutiis. 



13. S. Iieterochaetus 



14. S. californicus. 



15. .S". pacificus. 



16. S. paludosus. 



17. S. flnviatilis. 



downwardly barbed. 



18. .S". microcarpus. 



19. S. pallidus. 



20. S. congdoni. 



21. 5". lincatus. 



22. 5. criniger. 



1. Scirpus nanus Spreng. 



Dwarf Club-rush. 



Fig-, 



646. 



Scirpus nanus Spreng. Pug. 1: 4. 1815. 



Eleocharis pygmaca Torr. Ann. Lye. N. Y. 3: 313. 1836. 



Annual ; roots fibrous ; culms filiform, flattened, 

 grooved, tufted, erect or ascending, 2-5 cm. high, 

 bearing a scarious bladeless sheath near the base. 

 Spikelet solitary, terminal, ovoid-oblong, rather 

 acute, 3-8-flowered, 2-3 mm. long, not subtended by a 

 bract ; scales ovate or lanceolate, pale green, the 

 lower obtuse, the upper subacute ; bristles about 6. 

 downwardly barbed, longer than the achene ; stamens 

 3; style 3-cleft; achene oblong, 3-angled, pale, pointed 

 at each end, smooth. 



Muddy jilaces in salt marshes, coasts of Washington and 

 British Columbia; PCucamonga, California; about salt springs 

 in Michigan and New York; Atlantic Coast from Cape Bre- 

 ton Island to Florida; Gulf Coast, Florida to Texas; Cuba; 

 coasts of Europe. Type locality: Germany. 



2, Scirpus carinatus (H. & \.) A. Gray. 



Keeled Club-rush. 



Fig. 647. 



Tsolepis carinata H. & A. ; Torr. Ann. Lye. N. Y. 3: 349. 1836. 



Isolepis koilepis Steud. Syn. PI. Cyp. 318. 1855. 



Scirpus carinatus A. Gray, Proc. Am. Acad. 7: 392. 1868. 



Annual, fibrous-rooted; culms slender or nearly 

 filiform, tufted, smooth, 2.5-12 cm. high, trigonous 

 with slightly channeled sides, the upper sheath bear- 

 ing a linear-filiform leaf-blade 2 cm. long or less; 

 spikelet usually solitary, rarely 2 or 3, ovoid, 5-10- 

 flowered, 4-7 mm. long, subtended by a filiform bract 

 2 cm. long or less ; scales broadly ovate, greenish 

 brown, sharply keeled, acute, or the lower one long- 

 tipped ; bristles none; achene sharply trigonous, 

 smooth, brown, about 1 mm. long. 



Moist, grassy situations. Upper Sonoran Zone; near the 

 coast, Mendocino to Monterey Counties, California; Texas to 

 Missouri, Alabama and Tennessee. Type locality: near New 

 Orleans, Louisiana. 



