idence that at Turin seeds of _T.
pendula_ have reproduced the parent-form, _T. orientalis_.[771]

Every one must have noticed how certain individual trees regularly put
forth and shed their leaves earlier or later than others of the same
species. There is a famous horse-chesnut in the Tuileries which is
named from {363} leafing so much earlier than the others. There is also
an oak near Edinburgh which retains its leaves to a very late period.
These differences have been attributed by some authors to the nature of
the soil in which the trees grow; but Archbishop Whately grafted an
early thorn on a late one, and _vice versa_, and both grafts kept to
their proper periods, which differed by about a fortnight, as if they
still grew on their own stocks.[772] There is a Cornish variety of the
elm which is almost an evergreen, and is so tender that the shoots are
often killed by the frost; and the varieties of the Turkish oak (_Q.
cerris_) may be arranged as deciduous, sub-evergreen, and
evergreen.[773]

_Scotch Fir_ (_Pinus sylvestris_).--I allude to this tree as it bears
on the question of the greater variability of our hedgerow trees
compared with those under strictly natural conditions. A well-informed
writer[774] states that the Scotch fir presents few varieties in its
native Scotch forests; but that it "varies much in figure and foliage,
and in the size, shape, and colour of its cones, when several
generations have been produced away from its native locality." There is
little doubt that the highland and lowland varieties differ in the
value of their timber, and that they can be propagated truly by seed;
thus justifying Loudon's remark, that "a variety is often of as much
importance as a species, and sometimes far more so."[775] I may mention
one rather important point in which this tree occasionally varies; in
the classification of the Coniferae, sections are founded on whether
two, three, or five leaves are included in the same sheath; the Scotch
fir has properly only two leaves thus enclosed, but specimens have been
observed with groups of three leaves in a sheath.[776] Besides these
differences in the semi-cultivated Scotch fir, there are in several
parts of Europe natural or geographical races, which have been ranked
by some authors as distinct species.[777] Loudon[778] considers _P.