POACEAE 



107 



Panicle 6.5-8.5 cm. 

 long, broadly 

 ovoid, open. 

 b. Spikelets 3 mm. long or more. 



Panicle narrow, its branches usually appressed. 

 Panicle broad, nearly as wide as long. 



Spikelets 3 mm. long; blades commonly 



much elongated. 

 Spikelets over 3 mm. long; blades not 

 elongated. 

 Blades softly and densely pubescent 



beneath. 

 Blades glabrous or rarely puberulent 

 beneath. 

 II. Middle blades of the main culm more than 1.5 cm. 

 wide, usually cordate and clasping at the base. 

 Spikelets less than 3 mm. long. 



Blades glabrous on both surfaces. 



Spikelets less than 2 mm. long ; culms simple. 

 Spikelets more than 2 mm. long; culms 

 branched. 

 Sheaths papillose-hispid, especially the ter- 

 minal ones. 

 Sheaths glabrous. 

 Blades densely villous on both surfaces. 

 Spikelets 3 mm. long or more. 



Panicle narrow, its branches appressed. 

 Panicle open, its branches spreading. 

 Nodes barbed. 

 Nodes naked. 



49. P. Commonsianum. 

 54. P. xanthophysum. 



58. P. aculeatum. 



53. P. oligosanthes. 

 52. P. Scribnerianum. 



54. P. xanthophysum. 



62. P. Boscii. 

 61. P. latifolium. 



i. P. hemitomon Schult. In water: N. J. to Fla. and Tex. 



Known in our area only from West Cape May, and Bennett, Cape 

 May Co., N. J. 



2. P. verrucosum Muhl. In moist soil: Mass. to Mo., south to 



Fla. and Tex., mostly near the coast. 



Conn. Rare at New Haven. 



N. Y. On L. I. and S. I., unknown elsewhere. 



N. J. Throughout the coastal plain, unknown elsewhere. 



Pa. Delaware and Bucks counties, rare. 



Not uncommon on the coastal plain, very rare elsewhere in our 

 area. 



3. P. dichotomiflorum Michx. (P. proliferum of various Am. Auth. 



not of Lam.). In wet soil: Me. to Neb., Fla., Tex. and Cal. 

 Also in Trop. Am. 



Throughout the range, except the pine-barrens, always increasing 

 southward. 



