is transplanted from its native woods,
the flowers change colour, even during the first year.[895] It is
notorious that the improved varieties of the Heartsease (_Viola
tricolor_) when transplanted often produce flowers widely different in
size, form, and colour: for instance, I transplanted a large
uniformly-coloured dark purple variety, whilst in full flower, and it
then produced much smaller, more elongated flowers, with the lower
petals yellow; these were succeeded by flowers marked with large purple
spots, and ultimately, towards the end of the same summer, by the
original large dark purple flowers. The slight changes which some {387}
fruit-trees undergo from being grafted and regrafted on various
stocks,[896] were considered by Andrew Knight[897] as closely allied to
"sporting branches," or bud-variations. Again, we have the case of
young fruit-trees changing their character as they grow old; seedling
pears, for instance, lose with age their spines and improve in the
flavour of their fruit. Weeping birch-trees, when grafted on the common
variety, do not acquire a perfect pendulous habit until they grow old:
on the other hand, I shall hereafter give the case of some weeping
ashes which slowly and gradually assumed an upright habit of growth.
All such changes, dependent on age, may be compared with the changes,
alluded to in the last chapter, which many trees naturally undergo; as
in the case of the Deodar and Cedar of Lebanon, which are unlike in
youth and closely resemble each other in old age; and as with certain
oaks, and with some varieties of the lime and hawthorn.[898]

Before giving a summary on Bud-variation I will discuss some singular and
anomalous cases, which are more or less closely related to this same
subject. I will begin with the famous case of Adam's laburnum or _Cytisus
Adami_, a form or hybrid intermediate between two very distinct species,
namely, _C. laburnum_ and _purpureus_, the common and purple laburnum; but
as this tree has often been described, I will be as brief as I can.

Throughout Europe, in different soils and under different climates,
branches on this tree have repeatedly and suddenly reverted to both
parent-species in their flowers and leaves. To behold mingled on the
same tree tufts of dingy-red, bright yellow, and purple flowers, borne
on branches having widely differen