FESTUCEM 



227 



tapering into a slender point; 

 panicle 3 to 6 inches long, the 

 branches few and stiff, singly dis- 

 posed, naked below, bearing a few 

 1-sided clusters of spikelets, the 

 clusters being about 3^ inch wide, 

 green or purplish; spikelets com- 

 pressed, about ]4 inch long usu- 

 ally 3- or 4-flowered; first glume 

 l-nerved, acute; second glume 

 longer than the first, 3-nerved, 

 acuminate, ciHate on the keel; lem- 

 mas rather indistinctly 5-nerved, 

 cihate on the keel, short-awned. 

 During the flowering period the 

 branches are spread open by the 

 turgidity of prominent cushions of 

 tissue in the basal angle. Later 

 these cushions shrink and the 

 branches become appressed so that 

 in fruit the panicle is narrow and 

 almost spike-like. The tufts of 

 orchard-grass soon develop at the 

 base into large tussocks. In Eng- 

 land this grass is known as cock's- 

 foot. 



251. Poa L. — Blue-grass. 

 A large genus of over 100 

 species, found throughout the 

 world in the cooler parts and 

 in the high mountains of the 

 tropics. Annuals or mostly 

 perennials often with creeping 

 rhizomes. Spikelets in narrow 

 or open panicles, 2- to 6-fiowered ; lemmas 5-nerved, awn- 

 less, somewhat scarious at tip, smooth or hairy on the 

 nerves, sometimes cobwebby at base. This is one of the 



Fig. 53. Dactylis glomerata. In- 

 florescence, X Vs, spikelet, X7. 



