86 CYPERACEAE (SEDGE FAMILY) 



2. Scirpus caespitosus L. Sp. PL 48. 1753. Stems terete, filiform, in com- 

 pact turfy tufts, densely sheathed at the base, the upper sheath bearing a very 

 short awl-shaped leaf: scales of the ovoid spike rust-colored: involucral bract 

 a rigid-pointed scale, resembling the lowest proper scale of the spike : bristles 6, 

 smooth, longer than the smooth abruptly short-pointed achene. Colorado 

 and Wyoming; across the continent northward. 



3. Scirpus Olneyi Gray, Bost. Journ. Nat. Hist. 5: 238. 1845. Stem 3-wing- 

 angled, with deeply excavated sides, 4-12 dm. high, the upper sheath bearing 

 a short triangular leaf or none: spikes 6-12, closely capitate, overtopped by 

 the short involucral leaf: scales orbicular, smooth, mucronate-pointed : anthers 

 with a very short and blunt minutely-bearded tip: bristles 6, downwardly 

 barbed: achene ob ovate, plano-convex, brown, mucronate. Across the south- 

 ern part of the continent (possibly reaching Colorado) and northward in the 

 Atlantic States. 



4. Scirpus paludosus A. Nels. Bull. Torr. Bot. Club, 26: 5. 1899. Perennial 

 from corm-like tubers and horizontal rootstocks: culms 4-8 dm. high, tri- 

 angular, one face narrow and grooved : leaves equaling or exceeding the culms, 

 5-8 mm. wide, strongly nerve-grooved: involucral leaves 2, unequal, long: 

 spikelets 3-several, sessile in a dense cluster, ovate or oval, 10-20 mm. long, 

 brown: scales narrowly ovate, membranous, puberulent, 2-toothed and the 

 midrib prolonged into an awn: bristles usually 2, twice as long as the achene: 

 achene lenticular, 3 mm. long, broadly and truncately obovate, tipped with a 

 tooth; the surface shiny, finely pitted (under a lens). S. maritimus. Margins 

 of alkali ponds and lakes; said to range eastward to New England. 



5. Scirpus campestris Britton, 111. Fl. 1: 267. 1896. Very similar to the 

 preceding, 3-5 dm. high: leaves pale green, smooth, 2-4 mm. wide: involucral 

 leaves 2-3, the longer one much surpassing the inflorescence: spikelets 3-10, 

 oblong-cylindric, 15-25 mm. long, pale brown: scales ovate, 2-toothed and 

 awned: bristles 1-3, much shorter than the achene or none: style 2-cleft: 

 achene lenticular, obovate or oblong-ovate, mucronulate, yellow-brown, its 

 surface strongly cellular-reticulated. On the prairies and coming into our 

 range from the east; said to extend west to Nevada. 



6. Scirpus nevadensis Wats. King's Exp. 360. 1871. Stems clustered, 

 from running rootstocks, 1-5 dm. high, somewhat flattened above, leafy: 

 leaves nearly equaling the stem, deeply channeled or revolute, very rough on 

 the margins, sharply acute, 1-2 cm. long: scales brown and shining, ovate, 

 sharply carinate, acutish: bristles 1-3, not half the length of the achene: 

 style 2-cleft: achene broadly ovate, plano-convex, acute, 2 mm. long. Wet 

 saline soils; Wyoming to California. 



7. Scirpus americanus Pers. Syn. 1: 68. 1805. Stem sharply 3-angled 

 throughout, 2-10 dm. high, with concave sides: leaves 1-3, elongated: spikes 

 1-6, capitate, usually long, overtopped by the pointed involucral leaf: scales 

 ovate, sparingly ciliate, 2-cleft at the apex and awl-pointed from between the 

 acute lobes: anthers tipped with an awl-shaped minutely fringed appendage: 

 bristles 2-6, about equaling the obovate dark brown plano-convex smooth 

 mucronate achene. S. pungens. From the Atlantic to the Pacific, and not 

 infrequent in our range. 



8. Scirpus lacustris L. Sp. PL 48. 1753. Stems 0.5-2 m. high, leafless or 

 the lower sheaths bearing imperfect leaves: spikes rusty or chestnut-brown, 

 numerous and clustered in a one-sided compound umbel-like panicle, the 

 principal rays of which mostly surpass the involucral leaf: scales with a salient 

 midrib extending into a mucronate point, often pubescent, especially on the 

 mid-vein; usually pale with fine brown lines: bristles not exserted: achene 

 broadly obovate, terminating abruptly in a rather short beak. Widely dis- 

 tributed in North America and frequent in our range. 



9. Scirpus fluviatilis (Torr.) Gray, Man. 527. 1848. Stem stouter and 

 taller: Leaves fl:il, lu-oadly linear, the upper and those of the very long in- 

 volucre much exceeding the compound umbel: rays 5-9, elongated, recurved- 

 spreading: scales less lacerate and their awns less recurved: achene obovate, 

 sharply and exactly triangular, conspicuously pointed, dull, scarcely equaling 



