HOW TO KNOW THE GRASSES 



8a. Plants aquatic; pistUlate spikelets never on cobs 

 nor inclosed in bony rachis joints; staminate 

 spikelets with a single flower; glumes absent 



or reduced to minute ridges. Fig. 26 



TRIBE X, ZIZANIEAE, page 147 



8b. Plants not aquatic 9 



9a. Staminate and pistillate spikelets on the same 

 or separate plants; pistillate spikelets not on 

 a cob nor imbedded in bony rachis joints... 10 



I 



Figure 26 



9b. Staminate and pistillate spikelets on the same plant; pistillate 



spikelets on a cob or imbedded in bony joints of the rachis 



TRIBE XIIL TRIPSACEAE, page 184 



10a. Pistillate spikelets with 3-awned lemmas, the staminate ownless; 



plants spreading by stolons, on dry soils 



see Fig. 48. fScIeropogon bTevUolius) 



10b. Spikelets not awned 11 



11a. Lemmas glabrous, stiff and leathery, with 9 — 11 faint nerves; plants 

 of salty or alkali soil see Fig. 45. (Distichlis stricia) 



lib. Lemmas soft, papery, with 5 nerves, often with a cottony web at- 

 tached to the callus see Fig. 146. (Poa aTachniiem) 



17 



