Part 3, 1915] POAC3AE 215 



pubescent and also beset with stiff, spreading hairs about 1 mm. long, the short pedicels of the 

 somewhat crowded spikelets similarly hirsute; spikelets 3.4^3.8 mm. long, 1.5-1.7 mm. wide, 

 obovate, turgid, abruptly pointed, short-attenuate at base, a disinct internode of the rachilla 

 between the first and second glumes; first glume clasping, half as long as the spikelet or more, 

 acute, 5-nerved, the nerves usually anastomosing toward the apex, pilose; second glume and 

 sterile lemma pointed beyond the fruit, 5-nerved, obscurely reticulate between the nerves, 

 pilose, often densely so; fruit 2.6-3 mm. long, 1.5-1.6 mm. wide, elliptic, apiculate. 



Type locality: West Indies. 



Distribution: Cuba; Jamaica; Mexico to Panama; also in northern South America. 

 Illustrations: Trin. Ic. pi. 180 (as P. velutinosum) ; Field Columb. Mus. Publ. Bot. 3: 35 

 (as P. chartaginense) ; Contr. U. S. Nat. Herb. 15: /. 23. 



13. Panicum adspersum Trin. Gram. Pan. 146. 1826. 



Panicum Thomasianum Steud.; Doell, in Mart. Fl. Bras. 2 2 : 188, as synonym. 1877. 



Plants light-green, glabrous except as noted, ascending or spreading from a decumbent 

 base, rooting at the lower nodes, commonly rather freely branching; culms 30-100 cm. high, 

 compressed; leaf-sheaths shorter than the internodes, rather loose, densely ciliate at least 

 toward the summit; Hgule a ciliate-membranaceous ring scarcely 1 mm. long; blades ascending 

 or spreading, 5-15 cm., rarely as much as 20 cm. long, 8-20 mm. wide, abruptly acuminate, 

 sometimes ciliate at the rounded base, scabrous on the margin; panicles rather short-exserted, 

 6-15 cm. long, composed of few to many ascending spike-like racemes 3-10 cm. long, the slender 

 axes angled, scabrous, usually pubescent in the axils, bearing approximate, short-pediceled spike- 

 lets singly or two or three together on short branchlets along the under side; spikelets 3.2-4 mm. 

 long, 1.5-1.8 mm. wide, fusiform, turgid, abruptly acuminate; first glume clasping, about one 

 third the length of the spikelet, subacute, 5-nerved, glabrous ; second glume and sterile lemma 

 exceeding the fruit and pointed beyond it, 5-7-nerved, hispid at least toward the summit, or 

 sometimes hispidulous only, rarely glabrous, sometimes obscurely reticulate; fruit 2.2-3 mm. 

 long, obovate, obtuse. 



Typ© locality: Santo Domingo. 



Distribution: Florida, Bahamas, and the West Indies. 



Illustrations: Trin. Ic. pi. 169; Bull. U. S. Dept. Agr. Agrost. 7: f. 43 (as P. grossarium) ; 



Contr. U. S. Nat. Herb. 15: /. 24. 



This species has been erroneously referred to Panicum grossarium I/., but that is a synonym of 

 P. reptans (see page 213). 



14. Panicum arizonicum Scribn. & Merr. ; Merrill, Circ. U. S. Dep. 



Agr. Agrost. 32: 2. 1901. 



Panicum dissitiflorum Vasey, in S. Wats. Proc. Am. Acad. 24: 80, hyponym. . 1889. 



Panicum f us cum majus Vasey, Bull. U. S. Dep. Agr. Bot. 8: 26. 1889. 



Panicum fas ciculatum dissitiflorum Vasey; Merrill, Circ. U. S. Dep. Agr. Agrost. 32: 2, as synonym. 



1901. 

 Panicum arizonicum tenue Scribn. & Merr.; Merrill, Circ. U. S. Dep. Agr. Agrost. 32: 3. 1901. 

 Panicum arizonicum laeviglume Scribn. & Merr.; Merrill, Circ. U. S. Dep. Agr. Agrost, 32: 3. 1901. 

 Panicum arizonicum majus Scribn. & Merr.; Merrill, Circ. U. S. Dep. Agr. Agrost. 32: 3. 1901. 



Plants erect or ascending, sometimes decumbent at base and rooting at the lower nodes, 

 branching at the base arid lower nodes; culms 20-60 cm. high, glabrous except below the panicle, 

 the nodes sometimes slightly pubescent; leaf-sheaths shorter than the internodes or the upper 

 often overlapping, rather loose, glabrous to strongly papillose-hispid; Hgule a ring of hairs about 

 1 mm. long; blades rather thin, ascending or spreading, 5-15 cm. long, 6-12 mm. wide, rounded 

 at base, glabrous on both surfaces, or scabrous to papillose-hispid beneath, the scabrous, thin, 

 cartilaginous margin usually papillose-ciliate at base; panicles usually long-exserted, 7-20 cm. 

 long, the solitary', ascending, slender branches loosely flowered, the spikelets borne on very short 

 appressed branchlets, the pedicels and axes of branchlets, branches, and the entire panicle 

 finely pubescent and also copiously papillose-hirsute; spikelets 3.5-3,8 mm. long, obovate- 

 elliptic, abruptly pointed, attenuate at base as in P. molle, densely hirsute to glabrous; first 

 glume clasping, half the length of the spikelet, acute, 5-nerved; second glume and sterile lemma 

 pointed beyond the fruit, 5-nerved, the nerves, sometimes anastomosing as in P. molle; fruit 

 2.9-3 mm. long, 1.5-1.6 mm. wide, obovate-elliptic, apiculate. 



Type locality: Camp Lowell, Santa Cruz Valley, Arizona. 



Distribution : Western Texas to southern California, and Sonora to Oaxaca. 



Illustration: Contr. U. S. Nat. Herb. 15: /. 26. 



