12 HISTORY OF BRITISH FERNS. 



on some part of their surface, but usually on the lower face, 

 the seeds by wliich the plants may be propagated. These 

 are their external parts, and are called organs. 



The proper roots of Ferns are entirely fibrous, and they 

 proceed from the under-side of the stem, ^^•hen the latter 

 assumes the prostrate or creeping mode of groAvth ; 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 ; these, as they 

 extend by growth at their points, insinuate themselves 

 between the particles of earth to whicli 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 Ferns 

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

 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 Ferns, and ail the more highly- 

 developed plants, are nourished. 



The stem of a Fern is, according to its nature, called 

 sometimes a rhizome, sometimes a caudex, — which names 

 are given to particular modifications of the stems of plants. 



