The Natural History of British Grasses. 163 



follows that in order to understand descriptions so as to enable us 

 to distinguish one species from another, or to analyse them, great 

 care must first be taken to master the minute distinctive characters 

 which such parts may present. This done, the student of grasses 

 may soon know them tolerably well, whereas, if neglected, he 

 may attain to the knowledge of names, but it will only be in a 

 traditionary manner, and therefore with a constant liability to 

 error, according as his informer is well or ill acquainted with his 

 subject. 



This paper is intended to illustrate the following subjects : — 



1st. An account of the structure of grasses ; and 



2nd. To offer a system of classification or arrangement depen- 

 dent thereupon.* 



1. Structure of Grasses. — In grasses we meet with the following 

 parts, all of which, though tolerably constant in form in indi- 

 viduals of each species, yet in their variations in species make up 

 the sum of those distinctive characters which enable the botanist 

 to separate one species from another. Such are — 



The Root, or descending axis, consisting of root fibres and 

 rhizome. 



Culm, or ascending axis, consisting of stem, with its nodes and 

 joints. 



Leaves, the appendages of the axis, consisting of sheath, ligule, 

 lamina. 



Floicers, or reproductive organs, consisting of floral envelopes, 

 stamens, and pistils. 



Seeds, or Fruit, consisting of grains of various forms and sizes. 



The roots of grasses usually consist of small fibres, which, in 

 starting from the seed, burst through the radicle, or seed-root, 

 like the inner valve of a telescope from the outer ; this, which is 

 called by botanists Endorhizal, from two Greek words signifying 

 icithiii a sheath, may be well observed in the germination of such 

 large grasses as are presented in the cereals, as wheat, barley, 

 &c. Roots are sometimes hard and wiry, especially in such 

 species as grow in damp and boggy places ; whilst in others they 

 are exceedingly flexile, the main roots often creeping great dis- 

 tances in search of food, and then branching off into innumerable 

 fibrils, or rootlets, the ends of which, consisting of the newest 

 cells or growth, form the .ywiir/ioles, or suckers, by which nutri- 

 ment is taken from the soil into the plant system. It is hence 

 necessary, in the cultivation of grasses, that the soil for the recep- 

 tion of "the seed should be of good tilth, and especially that its 

 mechanical consistency should be such as that it will not greatly 



* The description of Species, with an account of their qualities, will follow in 

 our ne.\t Number. 



m2 



