12 
HISTORY OF BRITISH FERNS. 
on some part of their surface, but usually on the lower face, 
the seeds by which 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, 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 ; these, 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 Ferns 
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 Ferns, and all 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. 
