166 TJie JVatiiral Historij of British Grasses. 



Notched, in Bromiis mollis, soft brome or lop grass. 



In pairs, in Ammophila arundinacea, common sea-reed. 



Its value as a distinctive character may be drawn from an exa- 

 mination of Boa pratensis and B. trivialis, as it assists at a glance 

 to distinguish two grasses, much alike in appearance, though 

 verv distinct in habit and general properties. 



The use which this part of the leaf subserves would appear 

 to be that of more securely fastening the upper part of the 

 sheath to the culm, as without it the wind would tear the leaves 

 downwards, in which case their functions would become much, 

 disturbed, and they would soon wither and die. The flower in 

 grasses consists of the elements of an entire plant, each bunch 

 or locusta of flowers being but a grass in miniature, consisting 

 of a central axis or stem with its alternately arranged leaves, the 

 stamens, pistils, and seeds in the axils of which are but buds ; 

 this fact may at once be seen in viviparous specimens, such as 

 are often found in the Lolium pereime (perennial rye-grass) and 

 Cynosurus cristatus (crested dog's-tail), in which, instead of 

 flowers, we have complete buds, which we have indeed detached 

 and grown as distinct plants of their respective species. 



Now, in these examples the case is very different from that of 

 germination in the ear which takes place in laid and damp 

 wheat, as in the latter the seeds have been perfected, and ger- 

 mination takes place from heat and moisture in the usual manner ; 

 but in viviparous groioth the envelopes and their organs, instead 

 of growing seeds on the principle of arrested development, go 

 on growing into branches, and no seed is consequently per- 

 fected. 



Flowers consist of the following parts : — 



Glume = outer chaff-scales ] t-i i ^ 



„, , . ^ a- y ( -T loral envelopes. 



Glumel =inner chati-scales J '■ 



Stamens \ t? ^m- • 



T-,. ., ( r ertihzmg organs. 



Pistils J * ^ 



Seeds = grain--=reproductive organs. 



Floral envelopes, upon the theory just enunciated, consist of 

 metamorphosed leaves ; they are arranged in pairs, and each 

 scale starts from an opposite side of the central axis, but not 

 from the same point. The outer pair subserves the same use as 

 the calyx in other plants, and receives the name of calyx, glume 

 (E) ; the inner pair, or pairs — for sometimes several occur in a 

 single glume — is termed glumel, and the pieces of which either 

 are formed obtain the name of valves, the lower one being the 

 outer and the upper one the inner of each respectively. 



The glumes differ in shape, and in the presence or absence of 

 longitudinal lines or ribs ; it may be large enough to include or 

 conceal the glumel, or it may be considerably smaller than the 



