The Natural History of British Grasses. 167 



latter. Again, the outer and inner valve may vary in size and 

 shape, and, indeed, present many differences which will be ex- 

 plained in simple language in the descriptions of species. 



The glumel ( F), corolla, is subject to like differences in form and 

 proportion, facts which can only be well explained with a speci- 

 men in one's hand ; and it should not be forgotten that in grasses 

 we have to deal with plants which, though simple in their struc- 

 ture, present such minute differences that the eye must become 

 by use accustomed to examine and trace them, and as so many 

 characters are necessarily derived from such important organs 

 as the flowers, which are often small, even a pocket lens will fre- 

 quently be required to assist the ordinary vision.* 



The glumel is often found to be armed by a projecting spine 

 or beard ; this is of greater or less length, and is termed the 

 <2?o»,t and may be well observed in bearded wheat and in both 

 wild and cultivated barleys. This organ, when long and stiff, 

 and armed as it is sometimes with projecting spicule, renders 

 grasses where they occur exceedingly objectionable, especially 

 for hay, though the grass may be good if kept from flowering by 

 constant depasturing ; such are the species of Hordeum (wild 

 barley). 



The fertilizing organs consist of the stamens (H) which 

 possess the following parts : — 



a. The filament (H'), or thread which supports 



h. The anther (H"), or case in which is secreted 



c. The pollen, or fecundating dust. 

 The filament, Ijy reason of its length, may cause the anther 

 to be exserted or standing out from the flower, or from its short- 

 ness to be inserted or included in its valves, the anther may be 

 varied in its colour as follows : — J: 



Colourless, Poa annua, annual meadow-grass. 



Flesh colour, Phleum pratense, Timothy grass. 



Rose in Alopecurus pratensis, meadow ioxtail. 



Purple in Aira ccBspitosa, hassock grass. 



Yellow, Bromiis mollis, soft brome, and most grasses. 



Orange, Bromus erectus, upright brome. 



The pollen is usually of a light straw colour, but as it cannot 



be well examined without a tolerably good microscope, and even 



then would offer but doubtful specific characters, it need not be 



further mentioned here. In our British species of grasses we 



* For this purpose a lens of ordinarj- power -will suffice, such as may be pur- 

 chased at the optician's for about 9(/. 



t The awn, when present, may represent the blade of a leaf, whilst the glume 

 and glumel are the representatives of the sheath. 



X The colour varies much in the same species, some being more liable to 

 variation than others. 



