of the mature culms; blades linear, 2-4 (-5) mm. broad, usually flat but some- 

 times slightly involute, spreading to ascending, the surfaces pubescent, the backs 

 with several prominent raised nerves, the margin evident as a pale cartilaginous 

 narrow border which is ciliate-scabrid; leaf sheath broad, usually tomentose, 

 with a wide brownish subscarious margin (this long-ciliate and truncate above at 

 juncture with blade); ligule present as horizontal line of short pale hairs; scapes 

 rather rigid, subterete basally, usually flattened or oval in cross section just below 

 inflorescence, smooth or variously pubescent; spikelets at maturity a rich-reddish- 

 brown, lance-ovoid, 4-6 mm. long, acute, usually many in a rather dense pani- 

 culate system of cymes the primary branches of which are usually ascending, 

 pubescent (spikelets solitary in depauperate specimens); longest involucral bract 

 exceeding inflorescence, leaflifle in its vestiture, always with a prominently hairy 

 sheath; fertile bracts ovate, at maturity glabrous, reddish-brown except for a 

 paler often greenish area of midrib (this usually exserted as a short cusp, backs 

 of the midrib of lowermost scales often with some hairs); anthers 2, 0.7-1 mm. 

 long; style 2-branched, flattened, the edges fimbriate from near the base to the 

 base of the branches; achene obovoid, slightly apiculate, including the pedicel 

 1.7-2 mm. long, lenticular, finely foveate (pitted) with the pits arranged in many 

 vertical rows, sometimes slightly umbonate, at maturity a dark- to pale-brown 

 except for the pale margin; pedicel joint persistent, to 0.5 mm. long. 



Moist to wet sands, silts or clays of disturbed habitats such as pond or river 

 banks, roadside ditches, canals or agricultural grounds, Coastal Plain from N.C. 

 s. to n. Fla. and w. into Tex. 



6. Fimbristylis dichotoma (L.) Vahl. Fig. 208. 



Tufted perennial to 5 dm. tall or more; leaves from half as long to nearly 

 the length of the culms; blades linear. 2-5 mm. broad, flat to somewhat involute, 

 often glaucous and spreading, usually glabrous or rarely the lower surface pubes- 

 cent, with several prominent nerves, the margin evident as a pale cartilaginous 

 border that is ciliate-scabrid; sheaths broad, usually appressed-pubescent, with 

 a wide tan or reddish-brown subscarious margin that is ciliate and subtnmcate 

 apically; ligule present as a horizontal line of short hairs; scapes rigid, subterete 

 basally, usually flattened or oval in cross section just below the inflorescence, 

 the flattened edges usually scabrid; longest involucral bract usually longer than 

 the inflorescence, the blade similar to a leaf blade, the sheathing base sometimes 

 pubescent and ciliate; spikelets drab to brownish or reddish-brown, usually lance- 

 ovoid to oblong, 4-8 mm. long, acute, in an open to dense simple or compound 

 umbellate system of cymes (spikelets solitary in depauperate specimens); fertile 

 bracts broadly oblong to ovate, acute to obtuse at apex, the margin entire, the 

 surface smooth and pale- to dark-brown except for a paler often greenish midrib 

 that terminates at the apex or is excurrent as a short cusp; anthers 1 or 2, about 

 1 mm. long; style 2-branched, flattened with the edges fimbriate toward the 

 point of branching; achene lenticular-obovoid, sometimes fairly tumid, about 1 

 mm. long or slightly longer, apiculate. white to brownish, striate-reticulafe. the 

 cells rectangular, shallowly concave, horizontally arranged in (5) 10 to 12 longi- 

 tudinally rows. 



In moist or wet sunny savannahs, fields, grasslands and along roadsides in s.e. 

 Tex.; Old World species fast becoming a weed throughout the lower Coastal 

 Plain of s.e. U.S. 



7. Fiiiibristyli.s annua (All.) R & S. Fig. 210. 



Cespitosc, decumbent to ascending or erect annual, to 5 dm. tall (usually much 

 lower); leaves from half as long to nearly the length of the mature culms; blades 

 usually narrowly linear, glabrous to tomentose, 1-2 (-4) mm. wide, the backs 



408 



