FILICINEM. 
473 
the central cell of the archegonium ; the first roots arise beneath it, near the base of 
the archegonium' (/. c. p. 308). 
The processes of growth of the mature plant have not yet been ascertained with 
as much certainty as in other Vascular Cryptogams. In Ophioglossum vulgaium and 
Botrychium Lunaria the erect stem, buried deep in the earth and growing very 
slowly in length, branches but rarely. Even the comparatively thick roots rarely 
branch, and it is not known whether the branching is then monopodial or dicho- 
tomous. [According to Holle, the roots have a 
trilaterally pyramidal apical cell. They do not 
branch in Ophioglossum^ and in Botrychium their 
branches are probably produced laterally and not 
by dichotomy.] The flattened apex of the stem, 
surrounded by the insertions of the leaves, is buried 
deeply in the leaf-sheaths, and shows, in Ophioglos- 
sum vulgatwn, according to Hofmeister, a three- 
sided pyramidal apical cell as seen from above. 
The leaves have a sheathing base, and each is 
completely enclosed in the next older one, as shown 
in Fig. 289 in the case of Botrychium Lunaria. In 
Ophioglossum the relative positions of the parts at 
the end of the stem are still more complicated, from 
the fact that the rudimentary leaves, while com- 
pletely enclosed one within another, produce stipular 
structures which grow together so completely that 
each leaf appears as if enclosed in a kind of 
chamber formed by the cohesion of the stipular 
parts of leaves of different ages, recalling a similar 
arrangement in Marattia. These cohesions how- 
ever leave an opening at the apex of each chamber ; 
the apex of the stem is therefore exposed to the 
air through a narrow canal (Hofmeister). 
As soon as the plant has attained a certain 
age, each leaf bears a fructification, which forms a 
branch springing from the axial side of the leaf. 
In the genus Ophioglossum both the outer sterile 
and the fertile branch of the leaf are unbranched 
or only lobed ; in the Brasilian 0. palmatum the 
lamina is dichotomously lobed, and its margin bears 
on each side, as it joins the petiole, numerous fertile 
lobes or spikes of sporangia. In the genus Botry- 
chium both are branched and in parallel planes 
(Fig. 288, A and B). The earlier hypothesis of a cohesion of the two leaf-stalks of 
a fertile and of a sterile leaf is at once negatived by the history of development 
(Fig. 289); the history of development rather indicates, as Hofmeister first showed, 
that the fructification originates on the inner side of the leaf. In the mature state 
the fertile leaf- branch either separates from the sterile (green) one at the base or at 
Fig. 289.— Long-itudinal section throug-h the 
lower part of a mature plant oi Botrychutni Lu- 
naria. St stem, g g' fibro-vascular bundles, w a 
young root, b apex of the stem, b b' b" b"' the 
four leaves already formed, b'" the one unfolded 
durinCT the present year : b' shows the first indi- 
cation of the branching of the leaf ; in b" this has 
advanced further ; m is the median line of the 
sterile lamina, having already its lobes right and 
left which are not shown ;y" the fertile lamina with 
the young branches, on which the sporangia will 
be produced (X about lo). 
