260 



CYPERACEAE, 



Fimbristylis laxa Vahl. Weak Fimbristylis. (Fig. 606.) 



Fimbristylis laxa Vahl, Enum. 2: 292. 1806. 

 Fimbristvlis Baldwiniana Torr. Ann. Lye. N. Y. 3: 



344- 1836- 



Annual, roots fibrous, culms slender, flattened, 

 striate, densely tufted, erect or ascending, 2'-\ 

 long, usually longer than the leaves. Leaves flat 

 about l /z' f wide, glabrous or sparingly ciliate, 

 green and appearing glaucous, those of the involu- 

 cre 3-5, one of them often exceeding the umbel; 

 umbel simple or slightly compound, the cent 

 spikelet sessile; spikelets ovoid or ovoid-oblong, 

 3 // -6 // long, about \" in diameter; scales ovate, thin, 

 pale greenish-brown, subacute or mucronulate; 

 men i; style 2-cleft, pubescent; achene biconvex 

 obovoid, light brown, longitudinally ribbed, the rit 

 tubercled and connected by very fine cross-lines. 



In moist soil, southern Pennsylvania to Floric 

 west to Illinois, Missouri and Texas. Also in tropic 

 America. July-Sept. 



4. Fimbristylis Vahlii (Lam.) L,ink. Vahl' s Fimbristylis. 



Scirpus Vahlii Lam. Tabl. Encycl. i: 139. 1791. 

 Fimbristylis Vahlii Link, Hort. Berol. i: 287. 



1827. 

 Fimbristylis congesta Torr. Ann. Lye. N. Y. 3: 345. 



1836. 



Annual, culms very slender, densely tufted, 

 compressed, striate, erect or ascending, i'-4/ 

 high, longer than or equalling the leaves. 

 Leaves setaceous or almost filiform, rough, 

 those of the involucre 3-5, erect, much exceed- 

 ing the simple capitate cluster of 3-8 spikelets; 

 spikelets oblong-cylindric, obtuse, i"-\" long, 

 about W thick, many-flowered; scales lanceo- 

 late, pale greenish-brown, acuminate; stamen 

 i; style 2-cleft, glabrous below; achene minute, 

 biconvex, yellowish-white, cancellate by longi- 

 tudinal and transverse ridges. 



In moist soil, Missouri to Texas, east to North 

 Carolina and Florida. Also in ballast about the 

 eastern seaports. July-Oct. 



5. Fimbristylis autumnalis (L,.) R. &S. Slender Fimbristylis. (Fig. 608.) 



Sctrpus autumnalis L. Mant. 2: 180. 1771. 

 Fimbristylis aututnnalis R. & S. Syst. 2:97. 1817. 



Annual, roots fibrous, culms very slender, densely 

 tufted, flat, roughish on the edges or smooth, erect, 

 ascending or spreading, 3 '-15' long, usually much 

 exceeding the leaves. Leaves narrowly linear, flat, 

 W~i" wide, long-acuminate, glabrous, those of 

 the involucre 2-3, usually all shorter than the um- 

 bel; umbel compound or decompound, the primary 

 rays %'-\ l /i' long, the secondary filiform; spike- 

 lets linear-oblong, acute, 2 // -5 // long, W thick 

 or less, several-many flowered; scales ovate-lanceo- 

 late, subacute, strongly nmcronate, greenish-brown, 

 the midvein prominent; stamens 1-3; style 3-cleft; 

 achene obovoid, nearly white, 3-angled with a ridge 

 on each angle, very finely reticulated and some- 

 times roughened. 



In moist soil, Maine to Michigan, south to Florida 

 and Louisiana. Also in tropical America. June-Sept. 



