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242 HISTORY OR BEITISH RERNS.
are very dense, being compoundly branched. The side
branches, which measure about four inches in length, are
constantly branched at every joint with a whorl of branch-
lets averaging two inches in length, and sometimes these
branchlets put out another series of short branches. The
outline of the frond would be nearly pyramidal, were it not
that the extreme point becomes so slender as to be unable
to retain itself erect; the lateral branches are all drooping
or deflexed, and hence the elegant appearance of the full-
grown fronds. The ultimate branches are three-rihhed,
which gives them a triangular form; their joints terminate
in three long pointed teeth, one of the ribs extending undivided
to the apex of each tooth. The teeth are of the same
colour as the branch.
The section of the stem shows a series of shallow ridges
and furrows; opposite the latter a ring of largish cavities;
and alternating with these on the inner side, another ring of
very minute cavities, these latter again alternating with a
circle of angular cavities close to the inner margin of the
tube. The central cavity measures about half the diameter.
The fructification is an oblong-ovate cone-lihe head, consisting
of eighty or more pale brown peltate scales ranged
in whorls, and to which white spore-cases are attached.
e q u is e t um . 243
These, on bursting, disperse a great number of greenish-coloured
spores.
This species grows naturally in moist shady woods; and
though local, owing apparently to the conditions necessary
to its growth, namely, shade and moisture combined in a
pecuhar way, it is, nevertheless, a widely distributed plant,
and can hardly be considered as uncommon throughout the
United Kingdom. Its fertile stems are in perfection about
the middle of April, and its barren stems in June.
E q u ise tum T e lm a t e ia , EJirhart^—The Great Horsetail,
or Great Water Horsetail, of some; Great Mud Horsetail
of others. (Plate XX. fig. 2.)
This is one of those species in which the ordinary fertile
and the barren stems are perfectly dissimilar, the former
being short and quite simple, the latter tall and compoundly
branched. Occasionally a third sort of stem is produced,
late in the season, which may be called a kind of compromise
between the two. Mr. Newman describes such
stems as reaching maturity about August, and bearing a
very small proportion to the exclusively barren or fertile
stems. They are smaller, though with longer joints, have
shorter, less spreading sheaths, and bear catkins which
are smaller than usual. This state of the plant has been
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