POACEAE 



71 



Leaf-blades elongated ; racemes long and erect. 



Sheaths glabrous. 37. P. glabratum. 



Sheaths densely hirsute. 38. P. Floridawum* 



Racemes finally widely spreading. 



Sheaths glabrous ; blades glabrous or ciliate with 



short hairs. 39. P. gigantcwn, 



Sheaths densely hirsute ; blades ciliate with long 



hairs. 40. P. longicilium. 



gSpikelets flat, barely if at all convex on one side. 



Spikelets pubescent. 41. P. Buckleyanum, 



Spikelets glabrous. 



Sheaths, excepting the exterior basal ones, glabrous, or 



the lower sometimes pubescent at the summit. 

 Stems and sheaths much compressed, the former 



rather slender. 



Spikelets elliptic. 42. P. lividum. 



Spikelets orbicular or nearly so. 

 Leaf-blades glabrous. 



Spikelets 2-2.5 mm. long. 43. P. praecox. 



Spikelets 3 mm. long. 44. P. glaberrwmm. 



Leaf-blades hirsute : 



On the upper surface only : spikelets circular 



or nearly so. 45. P. tardnm. 



On both surfaces, strongly so on the lower : 



spikelets broadly obovate. 46. P. Kearney i. 



Stems and sheaths not much compressed, the former 



stout. 47. P. amplum. 



Sheaths densely hirsute. 48. P. Curtisianum. 



ffSpikelets acute, ciliate with very long hairs. 



Spikelets about 2.5mm. long; racemes numerous (usually 10 



or more). 49. P. Vaseyanum. 



Spikelets 3.5-4 mm. long ; racemes few to several (usually less 



than 8). 50. P. dilatatum. 



**Stem single, from a long scaly rootstock. 



Scales of the rootstock appressed-pubescent : rachis of the ra- 

 cemes not winged, the spikelets scattered. 51. P. biftdum. 

 Scales of the rootstock glabrous : rachis of the racemes winged, 



the spikelets crowded. 52. P. solitarium. 



2. Racemes in pairs at the summit of the stem, rarely in 3's or with 



another raceme below. 

 Stems tufted : racemes long and slender, the spikelets about 1.5mm. 



long. 53. P. conjugatum. 



Stems from long rootstocks : racemes short and stout, the spikelets 



exceeding 2 mm. long. 

 Spikelets ovate, 2.5-3 mm. long, pubescent; midnerve of the 



second scale present. 



Spikelets ovate-lanceolate, 3-4 mm. long, glabrous; midnerve 

 of the rugose second scale suppressed. 



54. P. distichum. 



55. P. vaginatum. 

 Stems 1.5-8 dm. long, compressed, from a float- 



1. Paspalum mucronatum Muhl. 



ing or creeping base, branched : leaf-sheaths loose or inflated, glabrous or hirsute ; blades 

 8-30 cm. long, 6-25 mm. wide, acuminate, rough : racemes 20-100, scattered, or sometimes 

 apparently whorled, 1-8 cm. long, slender, spreading, the rachis extending in an acumi- 

 nate point beyond the spikelets, the wings membranous and nearly enclosing the spikelets 

 at maturity : spikelets singly disposed in two rows, elliptic, 1.2-1.5 mm. long and about 

 0.6 mm. wide, pubescent. [P. fluitans Kunth.] 



In water, Virginia to southern Illinois, Missouri, Florida aad Texas. Also in tropical America. 

 Fall. 



2. Paspalum membranaceum Walt. Stems sometimes 6-8 dm. long, compressed, 

 creeping at the base, much branched : leaf-sheaths compressed, loose ; blades 3-8 cm. 

 long, 4-6 mm. wide, smooth: racemes .-3-7, erect, 2-3 cm. long, the rachis not extending 

 beyond the spikelets, the wings broad and nearly enclosing the spikelets at maturity : 

 spikelets singly disposed in two rows, 2-2.3 mm. long and 1.3-1.5 mm. wide, oval, gla- 

 brous. [P. Walterianum Sclmlt. ] 



In moist or wet soil, New Jersey and Delaware to southern Ohio, Florida and Texas. Fall. 



3. Paspalum blepharophyllum Nash. Stems tufted, 4-8 dm. tall : leaf-sheaths 

 glabrous, even on the margins ; blades linear-lanceolate to lanceolate, glabrous on both 

 surfaces, ciliate on the margins, 2.5 dm. long or less, 8-16 mm. wide : racemes usually 

 single, commonly 6-8 cm. long, sometimes longer : spikelets in pairs, 2 mm. long and 

 1.3-1.6 mm. wide, broadly obovate or oval, the first scale 3-nerved, usually pubescent with 

 short hairs, the second scale 3-nerved, or sometimes 2- nerved by the suppression of the 

 midnerve, glabrous. 



In sandy soil, Florida to Louisiana. Spring and summer. 



4. Paspalum propinquum Nash. Stems tufted, 8-10 dm. tall : basal leaf-sheaths 

 pubescent, the remaining ones glabrous ; blades glabrous on both surfaces, ciliate on the 

 margins with stiff hairs, linear, erect or nearly so, 5-20 cm. long, 5-10 mm. wide : racemes 

 rather slender, 8-12 cm. long, in 1's or 2's : spikelets in pairs, on shorter pubescent pedi- 



