













6 THE BRITISH FERNS. 
form of a rhizome, the roots are produced here and there from its 
under surface as it creeps along upon or beneath the surface. When, 
however, the stem is caudiciform, whether erect or decumbent, the 
roots proceed from among the bases of the old fronds, issuing from 
the stem on all sides, and sometimes overlying each other in 
masses. In these cases the fibres or roots are very frequently 
wiry and rigid in texture, and comparatively coarse. In some of 
the New Zealand tree Ferns,* Cyathea medullaris for example, 
the fibrous roots which push out from the lower part of the stem 
closely overlie each other, and form a kind of buttress of variable 
thickness around its base, extending more or less upwards. This 
growth sometimes attains a girth of six or seven feet, extending 
upwards and gradually lessening in thickness to the height of ten feet 
or more from the ground. In the Cyathea dealbata, also, these aérial 
roots form a wiry fibrous mass exterior to the true stem, gradually 
enlarging so as to become about a foot and a-half in diameter 
towards the base. The tendency of the rootlets is usually down- 
wards, but sometimes, as at the upper part of the crown of Osmunda 
regalis, they may be observed shooting out in all directions, some 
of them being directed upwards. The root-fibres often form 
entangled masses of considerable size. The fibres are sometimes 
simple, oftener branched, and generally, as before remarked, velvety ` 
or downy on the younger portions. These organs, of course, act as 
absorbents to supply the plants with nutriment, which nutriment is 
obtained from the soil in the case of the terrestrial species, and more 
or less from the atmosphere in those which are of epiphytal habit. 
‚The Stem of the Fern, often erroneously in popular language 
called the root, assumes two distinct forms, the peculiarities of 
which have been employed by Mr. J. Smith as primary characters 
in a new mode of classifying Ferns, which he has proposed.t These 
* Ralph, in Journal of Proceedings of the Linnean Society, iii. 165. 
+ J. Smith, Botany of the Voyage of H.M.S. Herald, 226. 

