GENERA OF GRASSES OF THE UNITED STATES, 231 
Panicwm virgatum L. (fig. 139) switch-grass, an erect perennial 3 to 
5 feet tall, with open spreading panicle, is common in the eastern half 
Fia. 139. — Switch-grass, Panicum virgatum. Plant, X 1 ; two views of spikelet and 
fertile floret, X 10. 
of the United States. It is a constituent of prairie hay. Panicum 
bulbosum H. B. K., of the Southwest develops well-marked corms 
