n states,
"for many years has had one bough of a totally different character to
the rest of the tree, or of any other ash-tree which I have seen; being
short-jointed and densely covered with foliage." It was ascertained
that this variety could be propagated by grafts.[870] The varieties of
some trees with cut leaves, as the oak-leaved laburnum, the
parsley-leaved vine, and especially the fern-leaved beech, are apt to
revert by buds to the common form.[871] The fern-like leaves of the
beech sometimes revert only partially, and the branches display here
and there sprouts bearing common leaves, fern-like, and variously
shaped leaves. Such cases differ but little from the so-called {383}
heterophyllous varieties, in which the tree habitually bears leaves of
various forms; but it is probable that most heterophyllous trees have
originated as seedlings. There is a sub-variety of the weeping willow
with leaves rolled up into a spiral coil; and Mr. Masters states that a
tree of this kind kept true in his garden for twenty-five years, and
then threw out a single upright shoot bearing flat leaves.[872]

I have often noticed single twigs and branches on beech and other trees
with their leaves fully expanded before those on the other branches had
opened; and as there was nothing in their exposure or character to
account for this difference, I presume that they had appeared as
bud-variations, like the early and late fruit-maturing varieties of the
peach and nectarine.

Cryptogamic plants are liable to bud-variation, for fronds on the same
fern are often seen to display remarkable deviations of structure.
Spores, which are of the nature of buds, taken from such abnormal
fronds, reproduce, with remarkable fidelity, the same variety, after
passing through the sexual stage.[873]

With respect to colour, leaves often become by bud-variation zoned,
blotched, or spotted with white, yellow, and red; and this occasionally
occurs even with plants in a state of nature. Variegation, however,
appears still more frequently in plants produced from seed; even the
cotyledons or seed-leaves being thus affected.[874] There have been
endless disputes whether variegation should be considered as a disease.
In a future chapter we shall see that it is much influenced, both in
the case of seedlings and of mature plants,