572 Nash : The dichotomous Panjcums 



Panicum flavovirens 



A densely tufted lig'ht green perennial, gkibrous, with the ex- 

 ceptions noted below. Culms 2-3 dm. tall, slender, finally much 

 branched : leaves 2 or 3 ; sheaths very short, those of the primary 

 leaves about one third as long" as the internodes^ one margin 

 usually extending above the other, making the summit of the 

 sheath more or less oblique, the lower sheaths ciliate on the 

 margin, the exterior basal ones pubescent all o\xt ; ligulc a deiise 

 ring of short hairs about 0.3 mm. long; blades thin, erect, w^ith- 



out a white margin or nearly so, entire or very minutely serrulate, 

 hence smooth or nearly so on the margin, linear-lanceolate, those 

 on the main culm 2.5-4 cm. long, 2.5-4 mm. wide, commonly 

 minutely pubescent on the lower surface between the nerves, those 

 on the branches much shorter, the basal blades longer, 4-6 cm. 

 long: panicle much exserted, 3-4 cm. long, broadly ovate, its 

 branches spreading, the larger 1—2 cm. long, the secondaiy 

 panicles much smaller, barely exserted and with spreading 

 branches : spikelets 1.5 mm. long and 0.7 mm. broad, elliptic, the 

 outer 3 scales densely pubescent with spreading hairs, the first 

 scale 1 -nerved, broadly ovate, obtuse, about one half as long as 

 the spikelet, the second and third scales 7-nerved, about equal in 

 length, the fourth scale yellowish-white, 1.3 mm. long and about 

 0.6 mm. wide. 



Type collected by the writer in Lake Co., Florida, June 16-30, 

 1895, no, 2061 ; growing in swampy woods along the edge of 

 road leading to the ford near the J. T. & K. W. R. R. bridge 

 across the Wekiva river. No. 2487a, collected in a similar habitat 

 at Lake City, Columbia Co., in the same state, on Aug, 30, 1895, 

 is also referred here. 



Differs from P, alboinar^iJiatum in the thin linear-lanceolate 

 blades which are entirely or almost devoid of the white margin, 

 and barely if at all rough on the margins. \\\ P. alboniarginatiim 

 the blades arc very thick, much broader, and with a wide strongly 

 serrulate wdiite margin which is much thickened. 



Panicum Helleri 



A tufted perennial, glabrous, with the exceptions noted below. 

 Culms 2-4 dm. tall, apprcssed-pubcsccnt below wath long hairs, 

 the nodes sparingly barbed, finally branched: leaves 5; sheaths 

 shorter than the internodes, the middle ones only about one half 

 as long, ciliate on the exterior margin, bearing between the promi- 

 nent nerves scattered papillae, from w^hich sometimes arise stiff 



