260 NORTH AMERICAN FLORA [Volume 17 



139. Panicum acuminatum v Sw. Prodr. 23. 1788. 



Panicum ornatum Desv.; Hamilt. Prodr. 11. 1825. 



Panicum dichotomum acuminatum Sw.; Griseb. Fl. Brit. W. Ind. 553. 1864. 



Panicum comophyllum Nash, Bull. Torrey Club 30: 380. 1903. 



Vernal culms leafy, ascending from a geniculate base, 20-70 cm. high, densely villous with 

 soft, spreading hairs, rarely glabrate above, the nodes more or less bearded ; leaf -sheaths velvety 

 papillose- villous or the upper glabrate; ligule 2-3 mm. long; blades ascending or spreading, 

 4-8 cm. long, 6-13 mm. wide, lanceolate, slightly cordate at base, sharply acuminate, usually 

 ciliate, the lower surface velvety papillose-pub erulent, the upper surface from appressed papil- 

 lose-pubescent to long- villous, or nearly glabrous except for long hairs near the base or margin ; 

 panicles 3-10 cm. long, about as wide, the axis usually villous, the branches flexuous, the lower 

 spreading or even reflexed; spikelets 1.8-1.9 mm. long, 0.9 mm. wide, obovate, turgid, abruptly 

 subacute, pilose ; first glume about one third the length of the spikelet, subacute ; second glume 

 and sterile lemma barely equaling the fruit at maturity; fruit 1.3-1.4 mm. long, 0.9 mm. wide, 

 elliptic, abruptly acute. 



Autumnal phase appearing early, the primary culms branching at all but the uppermost 

 nodes before the maturity of the primary panicles, these branches often exceeding the culm, 

 more or less zigzag, repeatedly branching, the ultimate branchlets in dense, short, flabellate 

 fascicles, the reduced blades flat or involute-pointed, the long hairs on the margins and upper 

 surface usually conspicuous. 



Type locality: Jamaica. 



Distribution: West Indies; also in Colombia. 



Illustration: Contr. U. S. Nat. Herb. 15: /. 229. 



140. Panicum auburne Ashe, Bull. N. Car. Exp. Sta. 175: 115. 



1900, 



Vernal phase grayish velvety-villous throughout; culms tufted, 20-50 cm. high, geniculate 

 at base, widely spreading, soon becoming branched and decumbent, rather slender, densely 

 papillose-silky- villous below, velvety with copious silky hairs intermixed above; leaf -sheaths 

 usually abbut half the length of the internodes, villous like the culms; ligule 3-4 mm. long; 

 blades rather thin, ascending, 3-7 cm. long, 3-5 mm. wide, acuminate, slightly narrowed toward 

 the base, the upper surface velvety with copious long, silky hairs intermixed, especially toward 

 the base, the lower surface silky- villous or velvety, the nerves somewhat conspicuous ; panicles 

 short-exserted, 3-5 cm. long, about as wide, the axis velvety, with long, silky hairs intermixed, 

 the flexuous branches ascending or spreading; spikelets 1.3-1.4 mm. long, 0.8-0.9 mm. wide, 

 obovate, very turgid, densely papillose-pubescent; first glume one third to half the length of 

 the spikelet, acute; second glume and sterile lemma equal and covering the fruit at maturity; 

 fruit 1.1-1.2 mm. long, 0.8 mm. wide, obovate-elliptic, minutely pointed. 



Autumnal phase early becoming diffusely branched at all the nodes, prostrate-spreading, 

 forming large mats, the branches curved upward at the ends ; earlier branches longer than the 

 primary internodes, the ultimate branchlets in short fascicles with involute-pointed blades 

 1-2 cm. long, the numerous turgid little spikelets clustered at their bases; winter rosette ap- 

 pearing rather late, the lanceolate blades silky-villous like those of the primary culm. 



Type locality: Auburn, Alabama. 



Distribution: Virginia to Florida, and west to Louisiana. 



Illustration: Contr. U. S. Nat. Herb. 15: /. 2 30. 



141. Panicum Thurowii Scribn. & Smith; Scribn. Circ. U. S. Dep. 



Agr. Agrost. 16: 5. 1899. 



Vernal form bluish-green, but drying olive; culms tufted, 35-70 cm. high, erect or ascending, 

 villous, the nodes bearded with spreading hairs, usually a glabrous ring below; leaf -sheaths 

 long, the lower often overlapping, the upper shorter than the internodes, sparsely or rather 

 densely villous; ligule 4 mm. long; blades rather stiff, ascending or spreading, 7-12 cm. long, 

 or the uppermost only 2-3 cm. long, 6-10 mm. wide, acuminate, often somewhat involute 

 toward the apex, narrowed toward the rounded base, the upper surface sparingly pilose toward 



