156 Transactions of the Society. 



the young plant, by means of its rootlets and leaves, is in a position 

 to supply itself with nourishment. 



Amongst British species there are usually two empty glumes, 

 but in Panicum, Setaria, Phalaris, Anthoxanthum, and Hierochloa, 

 there are one or two extra empty glumes, but these seem to be 

 flowering glumes reduced, and more or less rudimentary. In 

 Lolium there is only one empty glume, except on the terminal 

 spikelet, which has the normal number, two. Empty glumes are 

 altogether absent in Leersia oryzoides and Nardus, unless a small 

 tooth on one side of the little cavity bearing the spikelet of the 

 latter may be regarded as a glume reduced to the smallest propor- 

 tions visible. 



The empty glumes are usually persistent on the axis after the 

 flowering glumes with their contents fall away, but in Panicum 

 and Setaria there is a joint below the empty glumes, so that 

 they fall away at maturity. As a rule, the empty glumes are 

 more or less chaffy and large, so as to inclose the rest of the 

 spikelet wholly in the young stage, and wholly or only partly at 

 maturity. The grasses which have only one fertile flower in a 

 spikelet are well covered and protected by the empty glumes, 

 and Avena, Deschampsia, Aira, Holcus, Arrhenatherum, and Sieg- 

 lingia, are instances where the large, chaffy, empty glumes cover 

 the two to three flowers present. 



The flowering glume is mostly rolled round the caryopsis, or 

 fruit, usually contains a smaller organ, known as the pale, and the 

 two inclose and protect the ripe fruit, in many cases being more or 

 less adherent to it. In nearly all cases the caryopsis is inclosed 

 by the glume and pale, when the so-called grain is dressed and 

 spoken of as seed, as in the Oat and Eye-grass. The common, 

 or cultivated wheat (Triticum sativum) is a rare exception, the fruit 

 or caryopsis being readily separable from the glumes. 



In Hordeum (the Barley) the spikelets are in threes, and only 

 one or two contain a perfect flower. The empty glumes are often 

 reduced to mere awns. 



In some species one flower has stamens only, and some are 

 always monoecious or dioecious. Sometimes the whole spikelet 

 contains only two glumes, one empty, the other flowering, with 

 or even without a palea. Though the family is very natural, 

 these differences and reductions render it very difficult. 



A characteristic feature is the " awn." The midrib of the 

 flowering glumes, or of the intermediate empty ones, or of all the 

 glumes, is prolonged into a bristle which is sometimes very much 

 elongated. It proceeds either from the point of the glume, or from 

 a notch at the top, or in some cases leaves the midrib lower down. 



The awns appear to serve several different purposes. In some 

 species they are a protection against birds, and perhaps against 

 other animals ; in others they serve for the dissemination, or for 

 the sowing of the seed. 



