second 

 glumt 



J 



spiko 



Diagram of a flowering branch. 



Base of plant and underground parts of Poa pratensis. 



Forms of inflorescence: panicle, raceme, spike. 



Heteropogon contortus: (a) single joint of raceme showing awned sessile (perfect) spikelet partly 



hidden by the large pediceled (sterile) spikelet; (b) perfect spikelet from which sterile spikelet has 



fallen; (c) base of fertile spikelet showing the sharp callus formed by the obliquely disarticulating 



rachis joint; (d) raceme, showing homogamous pairs of spikelets at base; (e, f) diagrams showing 



structure of the raceme and points of disarticulation. 



431 



