10 HISTORY OF BRITISH FERNS. 



proceed from the under side of the stem, when the latter 

 assumes the prostrate or creeping mode of growth ; but 

 when it grows erect, they are produced towards its lower 

 end on all sides indifferently, from among the bases of the 

 decayed leaves or fronds. Fibrous roots are so called from 

 their consisting of little thread-like parts, which, as they 

 extend by growth at their points, insinuate themselves 

 between the particles of earth to which they have access, 

 and this in process of time becomes filled with their rami- 

 fications. They often form entangled masses, but are not 

 always sufficiently numerous for this. The fibres of Perns 

 are mostly of a somewhat rigid or wiry texture ; and in the 

 younger portions are often more or less covered with fine 

 soft hairs, which become lost with age. It is by means of 

 these organs chiefly, that Perns, and all the more highly de- 

 veloped plants, are nourished. 



The stem of a Pern, which is sometimes called a rhizome, 

 sometimes a caudex names given to particular modifications 

 of the stems of plants forms either an upright stock, which 

 in our native species seldom elevates itself above the sur- 

 face of the ground, but in certain exotic ferns reaches from 

 thirty to fifty feet or more in height, and gives a tree-like 

 character to the species ; or it extends horizontally either on 



