CYPERACEAB (SEDGB FAMII^Y) 



187 



271. r. laxa. 



Var. pub^rula (Miclix.) Britton. Leaves and scapes 

 pubescent. — Ga. and Fla. to Tex. ; also n. in the flat country 

 to Ind., 111., and Mo. 



3. F. laxa Valil. Culms slender (0.5-7 dm. high) from 

 an annual root, vjeak, grooved and flattish ; leaves linear, 

 flat, ciliate-denticulate, glaucous^ sometimes hairy; spike- 

 lets ovoid, acute (0.4-1 cm. long) ; stamen 1 ; 

 achene conspicuously 6-S-ribbed on each side, 

 and with finer cross-lines. — Low ground, near 

 the coast, Pa. to Fla. and Tex. ; n. in the flat 

 country to 111. and Mo. July-Oct. (Trop. 

 Am.) Fig. 271. 



-*- -t- Spikelets glomerulate ; style glabrous. 



4. F. Vahlii (Lam.) Link. Dwarf tufted annual (0.3-2 dm. 



high); the culms, leaves and very elongated upright bracts. fili- 

 272. F. Vahlii. form; glomerule 0.3-1 cm. in diameter; spikelets 3-8, sub- 



cylindric, greenish or pale brown, the narrow scales acuminate ; 

 achene minute, transversely reticulate. — Damp sands, 

 etc., N..C. to Fla., Tex., and Mo.; introd. near Phila. 

 July-Oct. Fig. 272. 



* * Style 3-cleft ; achene triangular. 



6. F. autuminalis (L.) R. & S. Annual (1-4 dm. 

 high), in tufts ; culms flat, slender, diffuse or erect ; 

 leaves flat, acute ; umbel compound or decompound, the 

 very numerous slender-cylindric to fusiform brown spike- 

 lets 4-10 mm. long ; the mucronate-acuminate ovate- 

 lanceolate scales appressed ; stamens 1-3; achenes very 

 minute, 0.5 mm. long, smooth or 

 minutely roughened. — Low grounds. 

 Pa., 111., and Mo., south w. July- 

 Sept. (Trop. Am.) Fig. 273. ^- 



6. F. Frankii Steud. Similar, 

 0.1-2 dm. high ; the umbel simple or slightly compound 

 (or the spikelets solitary in dwarf plants); spikelets ellip- 

 soid or narrowly ovoid, castaneous, the slender tips of the 

 scales slightly spreading; achenes 0.75 mm. long. {F. 

 autumnalis Man. ed. 6, in part.) — Sandy shores, Me. to 

 Ont., and southw. Aug.-Oct. Fig. 274. 



F. autumnalis. 



274. F. Frankii. 



9. SCIRPUS [Tourn.] L. Bulrush or Club Rush 



Spikelets few-many-flowered, solitary or in a terminal cluster when it is sub- 

 tended by a 1-several-leaved involucre (this when simple often appearing like a 

 continuation of the culm); the scales in several ranks, or rarely inclining to be 

 2-ranked. Flowers to all the scales, or to all but one or two of the lowest, all 

 perfect. Perianth of 1-6 (or 8) bristles, or sometimes wanting. Stamens 2 or 

 3. Style 2-3-cleft, simple, wholly deciduous, or sometimes leaving a tip or 

 point to the lenticular or triangular achene. — Culms sheathed at base. (The 

 Latin name of the bulrush.) 



a. Involucre none, or merely the modified outer caducous scale of the soli- 

 tary terminal small (2.5-7 mm. long) spikelet; achene trigonous, 

 smooth b. 

 6 Perianth-bristles terete and setulose. 



Scales of the flattened spikelet membranous and awnless ; bristles 

 retrorselv barbed ; achenes beaked. 

 Achene 1 mm. long, constricted below the beak . . . . 1. S. nanus. 

 Achene 2-2.5 mm. long, the pale beak continuous with the body 2. S. pauoijlorus. 

 Scales of the terete spikelet with firm green midribs, that of the 

 outermost prolonged into a blunt awn ; bristles setulose with 

 spreading or ascending fine hairs ; acheuea beakless. 



