STRUCTURE, MORPHOLOGY, AND PHYSIOLOGY. 11 



spike or spike-like panicle (PJdeum, Alopecurus, etc.). 

 lu this case the primary branches are frequently grown 

 to the main axis, and consequently the secondary 

 branches appear to be arranged spirally on this (PMeum 

 pratense L.), while Ph. Boehmeri Wib. has free primary 

 branches. 



The supporting bracts of the branches of the inflo- 

 rescence are usually entirely aborted, but on the lowest 

 branches they often occur as rudiments, rarely as well- 

 formed glume-like scales (Sesleria), and still more rarely 

 (Anomochloa, Phyllostachys) they are well developed on 

 all the primary branches. Frequently the leaf of the 

 culm or branch which stands next to the inflorescence is 

 in the form of a sheath enclosing the spikelets (Zea ? , 

 Coix, Lygeum, etc.). The false panicles of some Andro- 

 pogonece (Andropogon, Nardus, Fig. 19) are interspersed 

 with leaves, and arise from branches supported by the 

 upper leaves of the culm, these branches in turn bearing 

 leaves and branching again. 



THE SPIKELET. The spikelets consist of an axis com- 

 posed of short articulations, two-ranked chaffy leaves 

 (glumes) (spiral in Streptochceta only), the first 1 to 6 of 

 which (usually 2) are sterile and known as empty 

 glumes or glumes only, while the following one to 

 many glumes (flowering glumes or lower palese) bear 

 in their axils a very short branch which begins with 

 a bractlet called palea (or superior palea) with its 

 back turned towards the axis, and ends with a flower.* 

 The end of the axis of the spikelet is either visible 

 beyond the upper flower (Fig. 84) or its growth is ar- 

 rested early ; in many one-flowered spikelets it is not 

 at all visible even in the earliest stage of them, and 

 consequently the flower is situated upon the end of the 

 axis. In this case there is no longer a true distinction 

 between empty and flowering glumes and paleas, for the 

 entire spikelet represents a single flower with many 



* In the figures the entire inflorescence is always designated by A, the 

 spikelets by B, the empty glumes by C, the flowering glumes by D, the 

 palea by E. Compare Fig. 90. 



