136 FLORA OF WASHINGTON AND VICINITY. 



"1st. Those with narrow leaves, small panicles, and small flowers, including the 

 varieties nitidum, harbulatum, and ciliatum, say, Microcarpw. 



"2d. Those of a larger or stronger growth, with broader leaves and ampler pani- 

 cles, with flowers generally somewhat larger. This includes what has been called 

 P. sphcerocarpiivi, Ell., and P. laxiflorum, Lam. 



"3d. A still larger form, with leaves broader and more rigid, and spikelets larger, 

 approaching some forms of P. latifolium (perhaps P. nervosum, Ell.), and which 

 probably should be considered a distinct species, or a variety of P. latifolium." 



A comparison of the Panicums of this group shows that the species which tend 

 most strongly to coalesce are P. latifolium, P. clandestinum, and P. dichotomum. These, 

 with perhaps P. microcarpon, seem to constitute one large polymorphous species. 



Middle of May to September, but chiefly in June. 



Panicum depauperatum, Muhl. 



June. 

 Panicum verrucosum, Muhl. 



Not common. September. 

 t Panicum Crus-galli, L. Barn yard-Grass. 

 July. 



Panicum Crus-galU, L., var. hispidum. Gray. 



Custis Spring. Apparently indigenous. August. 

 Setaria rerticillata, Beauv. Bristly Foxtail Grass. 



Waste lots in the city (Dr. Vasey). 

 + Setaria (/ZaMca, Beauv. Foxtail. 



July, August. 

 Setaria viridis, Beauv. Green Foxtail. Bottle-Grass. 



July, August. 

 Cenchrus tribuloides, L. Bur-Grass. Hedgehog-Grass. 



Reform School. Not common. 



t Tripsacum dactyloides, L. Gama-Grass. Sesame-Grass. 

 Along the Potomac. Not abundant. July. 



Erianthus alopecuroides. Ell. Woolly Beard-Grass. 

 Holmead Swamp; Terra Cotta. August, September. 



t Andropogon furcatus, Muhl. Beard-Grass. 

 August, September. 



Andropogon scoparius, Michx. 



SeptemlxT. 



Andropogon argenteus, Ell. 

 September, October. 



Andropogon Virginicus, L. Broom-Sage. 

 September, October. 



Andropogon macrourus, Michx. 



Marlboro' Road ; Sligo Creek. September, October. 



Sorghum nutans. Gray. Indian Grass. Wood-Grass. 

 August, September. 



