CYPERACEAE (SEDGE FAMILY) 



187 



271. F. laxa. 



Var. pubSrula (Michx.) Britton. Leaves -and scapes 

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

 to Ind., 111., and Mo. 



3. F. laxa Vahl. Culms slender (0.6-7 dm. high) from 

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

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

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

 achene conspicuously Q-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. 



- - 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 Jili- 

 272 F. Vahlii. f orm i 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. 



* * 8tyle 3-cleft; achene triangular. 



5. F. autumnalis (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 si ender-cylindric to pisiform brown spike- 

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

 lanceolate scales oppressed; stamens 1-3; achenes very 

 minute, 0.5 mm. long, smooth or 

 minutely roughened. Low grounds, 

 Pa., 111., and Mo., southw. July- 

 Sept. (Trop. Am.) FIG. 273. 



6. F. Frdnkii 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 

 874. F. Frankil. Ont., and southw, Aug.-Oct. FIG. 274. 



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.) 



. 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. 

 b. Perianth-bristles terete and setnlose. 



Scales of the flattened spikelet membranous and awnless; bristles 



retrorsely barbed ; achenes beaked. 



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

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

 Scales of the terete spikelet with (Inn green midribs, that of the 

 outermost prolonged into a blunt awn ; bristles setulose with 

 spreading or ascending fine hairs ; acheaes beaklew. 



273. F. auturnnalts. 



