488 PART IV. CLASSIFICATION. 



axils and are known as the glumes (Fig. 301 g}. Thus a spikelet 

 consists of a main axis bearing two rows of bracts of which the 

 two first and lowest are barren, while the succeeding ones bear 

 each a flower in its axil, and beneath each flower there is also 

 a bracteole (superior palea) belonging to the floral branch itself. 

 The inferior palese often have, either at the apex or else borne on 

 the midrib, a spinous process called the arista or awn (Fig. 301 gr} . 



The number of flowers in each spikelet varies, however, accord- 

 ing to the genus ; often there is but one, the lowest, with rudi- 

 ments of others above it ; if, however, only one of the upper flowers 

 is developed, then the lower palese bear no flowers in their axils 

 and are regarded as glumes, several being therefore present in such 

 a case. The spikelets themselves are in many genera, e.g. Rye 

 and Wheat (Fig. 302 B), arranged in two rows on a main axis ; the 

 inflorescence may then be designated a compound spike (see p. 

 440) ; in most of the other genera the main axis of the inflor- 

 escence bears lateral branches which are slender, of various length, 

 and often branched again, and which bear the terminal spikelets ; 

 in this way a panicle is formed, as in the Oat (Fig. 302 A}. This 

 may be either loose and spreading, with long lateral branches, or 

 compressed, with very short branches, e.g. Alopecurus. The posi- 

 tion of the branches of the panicle is more or less bilateral ; dorsi- 

 ventral, when (e.g. Festuca) the branchlets of the main branches 

 of the panicle all arise on the same side (unilateral or secund 

 panicle). 



The androecium consists commonly of one (Fig. 299 5) or two 

 (A) whorls of 2-3 stamens; when there is but one whorl of 

 stamens, it corresponds to the outer whorl in those flowers in 

 which two whorls are present. Sometimes (e.g. Luziola, Ochlandra, 

 Pariana) the stamens are numerous (about 18-20;, or there may 

 be but one or two. When there are normally only two stamens, 

 they are usually situated in the median plane (e.g. Anthoxanthum), 

 sometimes in the lateral plane (e.g. Coleanthus) ; but where this 

 is the result of suppression (Diarrhena, Orthoclada) they are 

 postero-lateral, the anterior stamen being suppressed : when there 

 is only a single stamen, this is generally the anterior stamen (e.g. 

 species of Festuca and Andropogon), the two postero-lateral 

 stamens being suppressed. 



The monomerous gynseceum consists of a single median carpel 

 (Fig. 299), bearing 1-3 styles (see p. 467) : the single, somewhat 

 campylotropous ovule is sessile on the ventral suture of the carpel. 



