36 THE BRACTS AND FLOWERS. 



alternating with the stamens in most grasses, have been sup- 

 posed to represent a reduced perianth; but their homology is not 

 satisfactorily demonstrated. 



To sum up, therefore, the spikelets of Graminecp, may be 

 described as composed of a series of alternate ^^wmes, distichously 

 imbricated along the axis. To be really useful, descriptions 

 should be clear and intelligible, and enable the reader to identify 

 the plant. He should describe only what he actually sees, not 

 what it may be theoretically imagined he ought to see. 



The empty glumes are often more or less boat-shaped, and 

 with the one to many flowers Avhich they include, constitute a 

 spikelet, spicula or locusta. One or both empty glumes may be 

 absent in certain cases. The spikelets are arranged in panicles, 

 racemes, spikes or heads. 



The floral glume usually resembles the two empty glumes in 

 having a midrib Avith an equal number of ribs on each side, 

 while the palea often has two ribs, with a thin membrane between, 

 which is often notched at the apex. 



It is of much importance in describing grasses to observe the 

 relative lengths, sizes, shape, number of ribs, the nature of the 

 awn, and the texture of the glumes and palea. 



The midrib of one or more glumes often extends upwards 

 from the apex into an awn, and in case of the floral glume, 

 the awn sometimes starts from a notch at the top ; sometimes 

 from the back below the apex, and is then said to be dorsal. 



The lower part of the awn is often twisted when dry, but 

 straightens when moist. If the lower part twists, the upper 

 part inclines at an angle. 



The glumes and the palea probably represent the sheaths of 

 leaves, and where an awn exists it sometimes represents the blade 

 of a leaf. This is quite well shown in proliferous flowers of 

 grasses, as seen in Figure 53, a proliferous floral glume of P7i/e«;« 

 pratense (Timothy). 



