30 
THE OAK FERN. 
midrib) at the point where the branches take their 
rise ; and another (of less botanical importance, but 
very helpful in distinguishing it from its near ally, 
the Lime-stone Polypody) is its perfect smoothness, 
a constant distinction, most easily seen on the stipes 
and rachis, but equally occuring over the whole plant. 
The fronds are divided so that each branch is pinnate 
at the base, pinnatifid toward the point ; the pinnae 
are also pinnate at their bases, then pinnatifid, and at 
their points acute and nearly entire ; the pinnules and 
ultimate lobes are oblong and obtuse, with a rather 
wavy midvein, from which the venules branch alter- 
nately, extending to the margin, — in those of moderate 
size simple with a sorus at each extremity, in the 
larger branched with the sorus on the lower branch. 
The fructification varies much, according to habitat 
and season, being sometimes very much crowded and 
sometimes very sparse. The spore-cases are small, 
roundish obovate (inversely egg-shaped), and attached 
by a slender stalk ; — the spores ovate (egg-shaped), 
oblong, or roundish, with a granular surface. 
Like the Beech Pern, the Dryopteris is found from 
the coast-level to a great elevation. It is very rarely 
if ever seen on the limestone, and must be classed as a 
slate fern, liking a rocky district, with running water, 
and the not stagnant moisture of woods, needing both 
shade and shelter. It is easily cultiveable in a mixture 
of fibry peat, or leaf-mould, mixed with blue stone, 
earth, or sand, either in the house or on artificial 
rock- work. 
