form of a rhizome, tho roots are jiroduood here and there from its
under surface as it creeps along upon or beneath tho surface. When,
however, the stem is caudiciform, whether erect or documhont, the
roots proceed from among tho bases of the old fronds, issuing from
tho stem on all sides, and sometimes overlying each other in
masses. In those cases tho fibres or roots aro very frequently
why and rigid in texture, and comparatively coarse. In some of
the New Zealand tree Ferns,* Cyathea medullaris for example,
tho 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 loss upwards. This
growth sometimes attains a girth of six or seven feet, extending
upwards and gradually lessening in thickness to tho height of ten feet
or more from the ground. In the Cyathea dealhata, also, these aerial
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 downwards,
hut sometimes, as at the upper part of the crown of Osmunda
reyalis, they may bo observed shooting out in all directions, some
of thorn 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 arc 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. I . Smith as primary characters
in a new mode of classifying Ferns, which he has proposed.! These
* Ralpli, ill Journal o f Procccdincjs o f the Linncean Society, iii. 165.
t J. Smith, Botany o f the Voyage o f IF.M.S. Herald, 226.
two forms are tliose of a caiidex and a rhizome. In the candex or
caudiciform stem, tho fronds rise from tho termination of the axis
of growth, oithor in a single series, or in a kind of crowded whorl,
so as to form a terminal crown. The young fronds in aU cases
spring from the inner side of those previously formod, their bases
becoming united and adherent with the axis, so that the older part
of tho stem consists of a combination of tho axis with tho bases of
tho fronds developed from it. This manner of growth is exemplified
in the common Male Fem, and in those species which form the
tree Ferns of the tropical forests. In tho rhizome or rhizomiform
stem, the fronds, which are more or less scattered, are developed
from the sides of the axis of growth, the point of which is apparently
in advance of the last formed fronds; they are, moreover, developed
from nodes formed on the rhizome, each node producing a single frond,
which has an articulation or joining at or near to the base of its stipes,
at which point it eventually separates spontaneously. The common
Polypody affords a good illustration of this mode of development.
The oaudioiform stem or caudex, is in numerous instances among
the dwarf horhaoeous species scarcely at aU. lengthened, but erect and
tufted, forming a oaespitoso series of crowns, whence tho fronds issue.
Even among the species of herbaceous habit, however, the oaudioiform
stem occasionally in age becomes considerably elongated, and
such instances, which may be found among our native species, afford
an imperfect and pigmy illustration of the manner in which the
trunks of the tropical tree Ferns are formed. This elongation of the
older caudioes may be observed frequently in the Osmunda regalis,
which among our native Ferns is that which most frequently assumes
this habit, being sometimes found with bare stems, a foot or more
in height. The same tendency, though in a less degree, may be
observed in very old plants of the Lastrea Filix-mas, Lastrea montana,
and Lastrea dilatata, and sometimes also in Athyrium Filix-feemina,
and Polysticlmm angulare.