Chapter XI (1)

ON BUD-VARIATION, AND ON CERTAIN ANOMALOUS MODES OF REPRODUCTION AND VARIATION.

BUD-VARIATIONS IN THE PEACH, PLUM, CHERRY, VINE, GOOSEBERRY, CURRANT,
AND BANANA, AS SHOWN BY THE MODIFIED FRUIT--IN FLOWERS: CAMELLIAS,
AZALEAS, CHRYSANTHEMUMS, ROSES, ETC.--ON THE RUNNING OF THE COLOUR IN
CARNATIONS--BUD-VARIATIONS IN LEAVES--VARIATIONS BY SUCKERS, TUBERS,
AND BULBS--ON THE BREAKING OF TULIPS--BUD-VARIATIONS GRADUATE INTO
CHANGES CONSEQUENT ON CHANGED CONDITIONS OF LIFE--CYTISUS ADAMI, ITS
ORIGIN AND TRANSFORMATION--ON THE UNION OF TWO DIFFERENT EMBRYOS IN ONE
SEED--THE TRIFACIAL ORANGE--ON REVERSION BY BUDS IN HYBRIDS AND
MONGRELS--ON THE PRODUCTION OF MODIFIED BUDS BY THE GRAFTING OF ONE
VARIETY OR SPECIES ON ANOTHER--ON THE DIRECT OR IMMEDIATE ACTION OF
FOREIGN POLLEN ON THE MOTHER-PLANT--ON THE EFFECTS IN FEMALE ANIMALS OF
A FIRST IMPREGNATION ON THE SUBSEQUENT OFFSPRING--CONCLUSION AND
SUMMARY.

This chapter will be chiefly devoted to a subject in many respects important, namely, bud-variation. By this term I include all those sudden changes in structure or appearance which occasionally occur in full-grown plants in their flower-buds or leaf-buds. Gardeners call such changes "Sports;" but this, as previously remarked, is an ill-defined expression, as it has often been applied to strongly marked variations in seedling plants. The difference between seminal and bud reproduction is not so great as it at first appears; for each bud is in one sense a new and distinct individual; but such individuals are produced through the formation of various kinds of buds without the aid of any special apparatus, whilst fertile seeds are produced by the concourse of the two sexual elements. The modifications which arise through bud-variation can generally be propagated to any extent by grafting, budding, cuttings, bulbs, &c., and occasionally even by seed. Some few of our most beautiful and useful productions have arisen by bud-variation.

Bud-variations have as yet been observed only in the vegetable {374} kingdom; but it is probable that if compound animals, such as corals, &c., had been subjected to a long course of domestication, they would have varied by buds; for they resemble plants in many respects. Thus any new or peculiar character presented by a compound animal is propagated by budding, as occurs with differently coloured Hydras, and as Mr. Gosse has shown to be the case with a singular variety of a true coral. Varieties of the Hydra have also been grafted on other varieties, and have retained their character.

I will in the first place give all the cases of bud-variations which I have been able to collect, and afterwards show their importance. These cases prove that those authors who, like Pallas, attribute all variability to the crossing either of distinct races, or of individuals belonging to the same race but somewhat different from each other, are in error; as are those authors who attribute all variability to the mere act of sexual union. Nor can we account in all cases for the appearance through bud-variation of new characters by the principle of reversion to long-lost characters. He who wishes to judge how far the conditions of life directly cause each particular variation ought to reflect well on the cases immediately to be given. I will commence with bud-variations, as exhibited in the fruit, and then pass on to flowers, and finally to leaves.

_Peach_ (_Amygdalus Persica_).--In the last chapter I gave two cases of
a peach-almond and double-flowered almond which suddenly produced fruit
closely resembling true peaches. I have also recorded many cases of
peach-trees producing buds, which, when developed into branches, have
yielded nectarines. We have seen that no less than six named and
several unnamed varieties of the peach have thus produced several
varieties of nectarine. I have shown that it is highly improbable that
all these peach-trees, some of which are old varieties, and have been
propagated by the million, are hybrids from the peach and nectarine,
and that it is opposed to all analogy to attribute the occasional
production of nectarines on peach-trees to the direct action of pollen
from some neighbouring nectarine-tree. Several of the cases are highly
remarkable, because, firstly, the fruit thus produced has sometimes
been in part a nectarine and in part a peach; secondly, because
nectarines thus suddenly produced have reproduced themselves by seed;
and thirdly, because nectarines are produced from peach-trees from seed
as well as from buds. The seed of the nectarine, on the other hand,
occasionally produces peaches; and we have seen in one instance that a
nectarine-tree yielded peaches by bud-variation. As the peach is
certainly the oldest or primary variety, the {375} production of
peaches from nectarines, either by seeds or buds, may perhaps be
considered as a case of reversion. Certain trees have also been
described as indifferently bearing peaches or nectarines, and this may
be considered as bud-variation carried to an extreme degree.

The _grosse mignonne_ peach at Montreuil produced "from a sporting
branch" the _grosse mignonne tardive_, "a most excellent variety,"
which ripens its fruit a fortnight later than the parent tree, and is
equally good.[813] This same peach has likewise produced by
bud-variation the _early grosse mignonne_. Hunt's large tawny nectarine
"originated from Hunt's small tawny nectarine, but not through seminal
reproduction."[814]

_Plums._--Mr. Knight states that a tree of the yellow magnum bonum
plum, forty years old, which had always borne ordinary fruit, produced
a branch which yielded red magnum bonums.[815] Mr. Rivers, of
Sawbridgeworth, informs me (Jan. 1863) that a single tree out of 400 or
500 trees of the Early Prolific plum, which is a purple kind, descended
from an old French variety bearing purple fruit, produced when about
ten years old bright yellow plums; these differed in no respect except
colour from those on the other trees, but were unlike any other known
kind of yellow plum.[816]

_Cherry_ (_Prunus cerasus_).--Mr. Knight has recorded (_idem_) the case
of a branch of a May-Duke cherry, which, though certainly never
grafted, always produced fruit, ripening later, and more oblong, than
the fruit on the other branches. Another account has been given of two
May-Duke cherry-trees in Scotland, with branches bearing oblong, and
very fine fruit, which invariably ripened, as in Knight's case, a
fortnight later than the other cherries.[817]

_Grapes_ (_Vitis vinifera_).--The black or purple Frontignan in one
case produced during two successive years (and no doubt permanently)
spurs which bore white Frontignan grapes. In another case, on the same
footstalk, the lower berries "were well-coloured black Frontignans;
those next the stalk were white, with the exception of one black and
one streaked berry;" and altogether there were fifteen black and twelve
white berries on the same stalk. In another kind of grape black and
amber-coloured berries were produced in the same cluster.[818] Count
Odart describes a variety which often bears on the same stalk small
round and large oblong berries; though the shape of the berry is
generally a fixed character.[819] Here is another striking case given
on the excellent authority of M. Carriere:[820] "a black Hamburgh grape
(Frankenthal) was cut down, and produced three suckers; one of these
was layered, and after a time produced much smaller berries, which
always ripened at least a fortnight {376} earlier than the others. Of
the remaining two suckers, one produced every year fine grapes, whilst
the other, although it set an abundance of fruit, matured only a few,
and these of inferior quality.

_Gooseberry_ (_Ribes grossularia_).--A remarkable case has been
described by Dr. Lindley[821] of a bush which bore at the same time no
less than four kinds of berries, namely, hairy and red,--smooth, small
and red,--green,--and yellow tinged with buff; the two latter kinds had
a different flavour from the red berries, and their seeds were coloured
red. Three twigs on this bush grew close together; the first bore three
yellow berries and one red; the second twig bore four yellow and one
red; and the third four red and one yellow. Mr. Laxton also informs me
that he has seen a Red Warrington gooseberry bearing both red and
yellow fruit on the same branch.

_Currant_ (_Ribes rubrum_).--A bush purchased as the Champagne, which
is a variety that bears blush-coloured fruit intermediate between red
and white, produced during fourteen years, on separate branches and
mingled on the same branch, berries of the red, white, and champagne
kinds.[822] The suspicion naturally arises that this variety may have
originated from a cross between a red and white variety, and that the
above transformation may be accounted for by reversion to both
parent-forms; but from the foregoing complex case of the gooseberry
this view is doubtful. In France, a branch of a red-currant bush, about
ten years old, produced near the summit five white berries, and lower
down, amongst the red berries, one berry half red and half white.[823]
Alexander Braun[824] also has often seen branches bearing red berries
on white currants.

_Pear_ (_Pyrus communis_).--Dureau de la Malle states that the flowers
on some trees of an ancient variety, the _doyenne galeux_, were
destroyed by frost: other flowers appeared in July, which produced six
pears; these exactly resembled in their skin and taste the fruit of a
distinct variety, the _gros doyenne blanc_, but in shape were like the
_bon-chretien_: it was not ascertained whether this new variety could
be propagated by budding or grafting. The same author grafted a
_bon-chretien_ on a quince, and it produced, besides its proper fruit,
an apparently new variety, of a peculiar form, with thick and rough
skin.[825]

_Apple_ (_Pyrus malus_).--In Canada, a tree of the variety called Pound
Sweet, produced,[826] between two of its proper fruit, an apple which
was well russetted, small in size, different in shape, and with a short
peduncle. As no russet apple grew anywhere near, this case apparently
cannot be accounted for by the direct action of foreign pollen. I shall
hereafter give {377} cases of apple-trees which regularly produce fruit
of two kinds, or half-and-half fruit; these trees are generally
supposed, and probably with truth, to be of crossed parentage, and that
the fruit reverts to both parent-forms.

_Banana_ (_Musa sapientium_).--Sir R. Schomburgk states that he saw in
St. Domingo a raceme on the Fig Banana which bore towards the base 125
fruits of the proper kind; and these were succeeded, as is usual,
higher up the raceme, by barren flowers, and these by 420 fruits,
having a widely different appearance, and ripening earlier than the
proper fruit. The abnormal fruit closely resembled, except in being
smaller, that of the _Musa Chinensis_ or _Cavendishii_, which has
generally been ranked as a distinct species.[827]

* * * * *

FLOWERS.--Many cases have been recorded of a whole plant, or single
branch, or bud, suddenly producing flowers different from the proper
type in colour, form, size, doubleness, or other character. Half the
flower, or a smaller segment, sometimes changes colour.

_Camellia._--The myrtle-leaved species (_C. myrtifolia_), and two or
three varieties of the common species, have been known to produce
hexagonal and imperfectly quadrangular flowers; and the branches
producing such flowers have been propagated by grafting.[828] The
Pompone variety often bears "four distinguishable kinds of
flowers,--the pure white and the red-eyed, which appear promiscuously;
the brindled pink and the rose-coloured, which may be kept separate
with tolerable certainty by grafting from the branches that bear them."
A branch, also, on an old tree of the rose-coloured variety has been
seen to "revert to the pure white colour, an occurrence less common
than the departure from it."[829]

_Crataegus oxycantha._--A dark pink hawthorn has been known to throw out
a single tuft of pure white blossoms;[830] and Mr. A. Clapham,
nurseryman, of Bradford, informs me that his father had a deep crimson
thorn grafted on a white thorn, which, during several years, always
bore, high above the graft, bunches of white, pink, and deep crimson
flowers.

_Azalea Indica_ is well known often to produce by buds new varieties. I
have myself seen several cases. A plant of _Azalea Indica variegata_
has been exhibited bearing a truss of flowers of _A. Ind. Gledstanesii_
"as true as could possibly be produced, thus evidencing the origin of
that fine variety." On another plant of _A. Ind. variegata_ a perfect
flower of _A. Ind. lateritia_ was produced; so that both _Gledstanesii_
and _lateritia_ no doubt originally appeared as sporting branches of
_A. Ind. variegata_.[831]

_Cistus tricuspis._--A seedling of this plant, when some years old,
produced, at Saharunpore,[832] some branches "which bore leaves and
flowers widely different from the normal form." "The abnormal leaf is
much less {378} divided, and not acuminated. The petals are
considerably larger, and quite entire. There is also in the fresh state
a conspicuous, large, oblong gland, full of a viscid secretion, on the
back of each of the calycine segments."

_Althaea rosea._--A double yellow Hollyock suddenly turned one year into
a pure white single kind; subsequently a branch bearing the original
double yellow flowers reappeared in the midst of the branches of the
single white kind.[833]

_Pelargonium._--These highly cultivated plants seem eminently liable to
bud-variation. I will give only a few well-marked cases. Gaertner has
seen[834] a plant of _P. zonale_ with a branch having white-edged
leaves, which remained constant for years, and bore flowers of a deeper
red than usual. Generally speaking, such branches present little or no
difference in their flowers: thus a writer[835] pinched off the leading
shoot of a seedling _P. zonale_, and it threw out three branches, which
differed in the size and colour of their leaves and stems; but on all
three branches "the flowers were identical," except in being largest in
the green-stemmed variety, and smallest in that with variegated
foliage: these three varieties were subsequently propagated and
distributed. Many branches, and some whole plants, of a variety called
_compactum_, which bears orange-scarlet flowers, have been seen to
produce pink flowers.[836] Hill's Hector, which is a pale red variety,
produced a branch with lilac flowers, and some trusses with both red
and lilac flowers. This apparently is a case of reversion, for Hill's
Hector was a seedling from a lilac variety.[837] Of all Pelargoniums,
Rollisson's Unique seems to be the most sportive; its origin is not
positively known, but is believed to be from a cross. Mr. Salter, of
Hammersmith, states[838] that he has himself known this purple variety
to produce the lilac, the rose-crimson or _conspicuum_, and the red or
_coccineum_ varieties; the latter has also produced the _rose d'amour_;
so that altogether four varieties have originated by bud variation from
Rollisson's Unique. Mr. Salter remarks that these four varieties "may
now be considered as fixed, although they occasionally produce flowers
of the original colour. This year _coccineum_ has pushed flowers of
three different colours, red, rose, and lilac, upon the same truss, and
upon other trusses are flowers half red and half lilac." Besides these
four varieties, two other scarlet Uniques are known to exist, both of
which occasionally produce lilac flowers identical with Rollisson's
Unique;[839] but one at least of these did not arise through
bud-variation, but is believed to be a seedling from Rollisson's
Unique.[840] There are, also, in the trade[841] two other slightly
different varieties, of unknown origin, of Rollisson's Unique: so that
altogether we have a curiously complex case {379} of variation both by
buds and seeds.[842] An English wild plant, the _Geranium pratense_,
when cultivated in a garden, has been seen to produce on the same plant
both blue and white, and striped blue and white flowers.[843]

_Chrysanthemum._--This plant frequently sports, both by its lateral
branches and occasionally by suckers. A seedling raised by Mr. Salter
has produced by bud-variation six distinct sorts, five different in
colour and one in foliage, all of which are now fixed.[844] The
varieties which were first introduced from China were so excessively
variable, "that it was extremely difficult to tell which was the
original colour of the variety, and which was the sport." The same
plant would produce one year only buff-coloured, and next year only
rose-coloured flowers; and then would change again, or produce at the
same time flowers of both colours. These fluctuating varieties are now
all lost, and, when a branch sports into a new variety, it can
generally be propagated and kept true; but, as Mr. Salter remarks,
"every sport should be thoroughly tested in different soils before it
can be really considered as fixed, as many have been known to run back
when planted in rich compost; but when sufficient care and time are
expended in proving, there will exist little danger of subsequent
disappointment." Mr. Salter informs me that with all the varieties the
commonest kind of bud-variation is the production of yellow flowers,
and, as this is the primordial colour, these cases may be attributed to
reversion. Mr. Salter has given me a list of seven differently coloured
chrysanthemums, which have all produced branches with yellow flowers;
but three of them have also sported into other colours. With any change
of colour in the flower, the foliage generally changes in a
corresponding manner in lightness or darkness.

Another Compositous plant, namely, _Centauria cyanus_, when cultivated
in a garden, not unfrequently produces on the same root flowers of four
different colours, viz., blue, white, dark-purple, and
particoloured.[845] The flowers of Anthemis also vary on the same
plant.[846]

_Roses._--Many varieties of the rose are known or are believed to have
originated by bud-variation.[847] The common double moss-rose was
imported into England from Italy about the year 1735.[848] Its origin
is unknown, but from analogy it probably arose from the Provence rose
(_R. centifolia_) by bud-variation; for branches of the common
moss-rose have several times been known to produce Provence roses,
wholly or partially destitute of moss: I have seen one such instance,
and several others have been recorded.[849] {380} Mr. Rivers also
informs me that he raised two or three roses of the Provence class from
seed of the old single moss-rose;[850] and this latter kind was
produced in 1807 by bud-variation from the common moss-rose. The white
moss-rose was also produced in 1788 by an offset from the common red
moss-rose: it was at first pale blush-coloured, but became white by
continued budding. On cutting down the shoots which had produced this
white moss-rose, two weak shoots were thrown up, and buds from these
yielded the beautiful striped moss-rose. The common moss-rose has
yielded by bud-variation, besides the old single red moss-rose, the old
scarlet semi-double moss-rose, and the sage-leaf moss-rose, which "has
a delicate shell-like form, and is of a beautiful blush colour; it is
now (1852) nearly extinct."[851] A white moss-rose has been seen to
bear a flower half white and half pink.[852] Although several
moss-roses have thus certainly arisen by bud-variation, the greater
number probably owe their origin to seed of moss-roses. For Mr. Rivers
informs me that his seedlings from the old single moss-rose almost
always produced moss-roses; and the old single moss-rose was, as we
have seen, the product by bud-variation of the double moss-rose
originally imported from Italy. That the original moss-rose was the
product of bud-variation is probable, from the facts above given and
from the moss-rose de Meaux (also a var. of _R. centifolia_)[853]
having appeared as a sporting branch on the common rose de Meaux.

Prof. Caspary has carefully described[854] the case of a six-year-old
white moss-rose, which sent up several suckers, one of which was
thorny, and produced red flowers, destitute of moss, exactly like those
of the Provence rose (_R. centifolia_): another shoot bore both kinds
of flowers and in addition longitudinally striped flowers. As this
white moss-rose had been grafted on the Provence rose, Prof. Caspary
attributes the above changes to the influence of the stock; but from
the facts already given, and from others to be given, bud-variation,
with reversion, is probably a sufficient explanation.

Many other instances could be added of roses varying by buds. The white
Provence rose apparently thus originated.[855] The double and
highly-coloured Belladonna rose has been known[856] to produce by
suckers both semi-double and almost single white roses; whilst suckers
from one of these semi-double white roses reverted to perfectly
characterised Belladonnas. Varieties of the China rose propagated by
cuttings in St. Domingo often revert after a year or two into the old
China rose.[857] Many cases {381} have been recorded of roses suddenly
becoming striped or changing their character by segments: some plants
of the Comtesse de Chabrillant, which is properly rose-coloured, were
exhibited in 1862,[858] with crimson flakes on a rose ground. I have
seen the Beauty of Billiard with a quarter and with half the flower
almost white. The Austrian bramble (_R. lutea_) not rarely[859]
produces branches with pure yellow flowers; and Prof. Henslow has seen
exactly half the flower of a pure yellow, and I have seen narrow yellow
streaks on a single petal, of which the rest was of the usual copper
colour.

The following cases are highly remarkable. Mr. Rivers, as I am informed
by him, possessed a new French rose with delicate smooth shoots, pale
glaucous-green leaves, and semi-double pale flesh-coloured flowers
striped with dark red; and on branches thus characterised there
suddenly appeared, in more than one instance, the famous old rose
called the Baronne Prevost, with its stout thorny shoots, and immense,
uniformly and richly coloured, double flowers; so that in this case the
shoots, leaves, and flowers, all at once changed their character by
bud-variation. According to M. Verlot[860] a variety called _Rosa
cannabifolia_, which has peculiarly shaped leaflets, and differs from
every member of the family in the leaves being opposite instead of
alternate, suddenly appeared on a plant of _R. alba_ in the gardens of
the Luxembourg. Lastly, "a running shoot" was observed by Mr. H.
Curtis[861] on the old Aimee Vibert Noisette, and he budded it on
Celine; thus a climbing Aimee Vibert was first produced and afterwards
propagated.

_Dianthus._--It is quite common with the Sweet William (_D. barbatus_)
to see differently coloured flowers on the same root; and I have
observed on the same truss four differently coloured and shaded
flowers. Carnations and pinks (_D. caryophyllus_, &c.) occasionally
vary by layers; and some kinds are so little certain in character that
they are called by floriculturists "catch-flowers."[862] Mr. Dickson
has ably discussed the "running" of particoloured or striped
carnations, and says it cannot be accounted for by the compost in which
they are grown: "layers from the same clean flower would come part of
them clean and part foul, even when subjected to precisely the same
treatment; and frequently one flower alone appears influenced by the
taint, the remainder coming perfectly clean."[863] This running of the
parti-coloured flowers apparently is a case of reversion by buds to the
original uniform tint of the species.

I will briefly mention some other cases of bud-variation to show how
many plants belonging to many orders have varied in their flowers;
numerous cases might be added. I have seen on a snap-dragon
(_Antirrhinum majus_) white, pink, and striped flowers on the same
plant, and branches with striped flowers on a red-coloured variety. On
a double stock (_Matthiola incana_) I have seen a branch bearing single
flowers; and {382} on a dingy-purple, double variety of the wall-flower
(_Cheiranthus cheiri_) a branch which had reverted to the ordinary
copper colour. On other branches of the same plant, some flowers were
exactly divided across the middle, one half being purple and the other
coppery; but some of the smaller petals towards the centre of these
same flowers were purple longitudinally streaked with coppery colour,
or coppery streaked with purple. A Cyclamen[864] has been observed to
bear white and pink flowers of two forms, the one resembling the
Persicum strain, and the other the Coum strain. _Oenothera biennis_ has
been seen[865] bearing flowers of three different colours. The hybrid
_Gladiolus colvillii_ occasionally bears uniformly coloured flowers,
and one case is recorded[866] of all the flowers on a plant thus
changing colour. A Fuchsia has been seen[867] bearing two kinds of
flowers. _Mirabilis jalapa_ is eminently sportive, sometimes bearing on
the same root pure red, yellow, and white flowers, and others striped
with various combinations of these three colours.[868] The plants of
the Mirabilis which bear such extraordinarily variable flowers, in
most, probably in all cases, owe their origin, as shown by Prof. Lecoq,
to crosses between differently-coloured varieties.

* * * * *

_Leaves and Shoots._--Changes, through bud-variation, in fruits and
flowers have hitherto been treated of, but incidentally some remarkable
modifications in the leaves and shoots of the rose and Cistus, and in a
lesser degree in the foliage of the Pelargonium and Chrysanthemum, have
been noticed. I will now add a few more cases of variation in
leaf-buds. Verlot[869] states that on _Aralia trifoliata_, which
properly has leaves with three leaflets, branches bearing simple leaves
of various forms frequently appear; these can be propagated by buds or
grafting, and have given rise, as he states, to several nominal
species.

With respect to trees, the history of but few of the many varieties
with curious or ornamental foliage is known; but several probably have
originated by bud-variation. Here is one case:--An old ash-tree
(_Fraxinus excelsior_) in the grounds of Necton, as Mr. Mason 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, by the nature of the soil.
Plants which have become variegated as seedlings, generally transmit
their character by seed to a large proportion of their progeny; and Mr.
Salter has given me a list of eight genera in which this occurred.[875]
Sir F. Pollock has given me more precise information: he sowed seed
from a variegated plant of _Ballota nigra_ which was found growing
wild, and thirty per cent. of the seedlings were variegated; seed from
these latter being sown, sixty per cent. came up variegated. When
branches become variegated by bud-variation, and the variety is
attempted to be propagated by seed, the seedlings are rarely
variegated; Mr. Salter found this to be the case with plants belonging
to eleven genera, in which the greater number of the seedlings proved
to be green-leaved; yet a few were slightly variegated, or were quite
white, but none were worth keeping. Variegated plants, whether
originally produced from seeds or buds, can generally be propagated by
budding, grafting, &c.; but all are apt to revert by bud-variation to
their ordinary foliage. This tendency, however, differs much in the
varieties of even the same species; for instance, the golden-striped
variety of _Euonymus Japonicus_ "is very liable to run back to the
green-leaved, while the silver-striped {384} variety hardly ever
changes."[876] I have seen a variety of the holly, with its leaves
having a central yellow patch, which had everywhere partially reverted
to the ordinary foliage, so that on the same small branch there were
many twigs of both kinds. In the pelargonium, and in some other plants,
variegation is generally accompanied by some degree of dwarfing, as is
well exemplified in the "Dandy" pelargonium. When such dwarf varieties
sport back by buds or suckers to the ordinary foliage, the dwarfed
stature sometimes still remains.[877] It is remarkable that plants
propagated from branches which have reverted from variegated to plain
leaves[878] do not always (or never, as one observer asserts) perfectly
resemble the original plain-leaved plant from which the variegated
branch arose: it seems that a plant, in passing by bud-variation from
plain leaves to variegated, and back again from variegated to plain, is
generally in some degree affected so as to assume a slightly different
aspect.

* * * * *

_Bud-variation by Suckers, Tubers, and Bulbs._--All the cases hitherto
given of bud-variation in fruits, flowers, leaves, and shoots, have
been confined to buds on the stems or branches, with the exception of a
few cases incidentally noticed of varying suckers in the rose,
pelargonium, and chrysanthemum. I will now give a few instances of
variation in subterranean buds, that is, by suckers, tubers, and bulbs;
not that there is any essential difference between buds above and
beneath the ground. Mr. Salter informs me that two variegated varieties
of Phlox originated as suckers; but I should not have thought these
worth mentioning, had not Mr. Salter found, after repeated trials, that
he could not propagate them by "root-joints," whereas, the variegated
_Tussilago farfara_ can thus be safely propagated;[879] but this latter
plant may have originated as a variegated seedling, which would account
for its greater fixedness of character. The Barberry (_Berberis
vulgaris_) offers an analogous case; there is a well-known variety with
seedless fruit, which can be propagated by cuttings or layers; but
suckers always revert to the common form, which produces fruit
containing seeds.[880] My father repeatedly tried this experiment, and
always with the same result.

Turning now to tubers: in the common Potato (_Solanum tuberosum_) a
single bud or eye sometimes varies and produces a new variety; or,
occasionally, and this is a much more remarkable circumstance, all the
eyes in a tuber vary in the same manner and at the same time, so that
the whole tuber assumes a new character. For instance, a single eye in
a tuber of the {385} old _Forty-fold potato_, which is a purple
variety, was observed[881] to become white; this eye was cut out and
planted separately, and the kind has since been largely propagated.
_Kemp's Potato_ is properly white, but a plant in Lancashire produced
two tubers which were red, and two which were white; the red kind was
propagated in the usual manner by eyes, and kept true to its new
colour, and, being found a more productive variety, soon became widely
known under the name of _Taylor's Forty-fold_.[882] The _Old
Forty-fold_ potato, as already stated, is a purple variety; but a plant
long cultivated on the same ground produced, not as in the case above
given a single white eye, but a whole white tuber, which has since been
propagated and keeps true.[883] Several cases have been recorded of
large portions of whole rows of potatoes slightly changing their
character.[884]

Dahlias propagated by tubers under the hot climate of St. Domingo vary
much; Sir R. Schomburgk gives the case of the "Butterfly variety,"
which the second year produced on the same plant "double and single
flowers; here white petals edged with maroon; there of a uniform deep
maroon."[885] Mr. Bree also mentions a plant "which bore two different
kinds of self-coloured flowers, as well as a third kind which partook
of both colours beautifully intermixed."[886] Another case is described
of a dahlia with purple flowers which bore a white flower streaked with
purple.[887]

Considering how long and extensively many Bulbous plants have been
cultivated, and how numerous are the varieties produced from seed,
these plants have not varied so much by offsets,--that is, by the
production of new bulbs,--as might have been expected. With the
Hyacinth a case has been recorded of a blue variety which for three
successive years gave offsets which produced white flowers with a red
centre.[888] Another hyacinth has been described[889] as bearing on the
same truss a perfectly pink and a perfectly blue flower.

Mr. John Scott informs me that in 1862 _Imatophyllum miniatum_, in the
Botanic Gardens of Edinburgh, threw up a sucker which differed from the
normal form, in the leaves being two-ranked instead of four-ranked. The
leaves were also smaller, with the upper surface raised instead of
being channelled.

In the propagation of _Tulips_, seedlings are raised, called _selfs_ or
_breeders_, which "consist of one plain colour on a white or yellow
bottom. These, being cultivated on a dry and rather poor soil, become
broken or variegated and produce new varieties. The time that elapses
before they break varies from one to twenty years or more, and
sometimes this change never takes place."[890] The various broken or
variegated colours which give value to all tulips are due to
bud-variation; for although the {386} Bybloemens and some other kinds
have been raised from several distinct breeders, yet all the Baguets
are said to have come from a single breeder or seedling. This
bud-variation, in accordance with the views of MM. Vilmorin and
Verlot,[891] is probably an attempt to revert to that uniform colour
which is natural to the species. A tulip, however, which has already
become broken, when treated with too strong manure, is liable to flush
or lose by a second act of reversion its variegated colours. Some
kinds, as Imperatrix Florum, are much more liable than others to
flushing; and Mr. Dickson maintains[892] that this can no more be
accounted for than the variation of any other plant. He believes that
English growers, from care in choosing seed from broken flowers instead
of from plain flowers, have to a certain extent diminished the tendency
in flowers already broken to flushing or secondary reversion.

During two consecutive years all the early flowers in a bed of
_Tigridia conchiflora_[893] resembled those of the old _T. pavonia_;
but the later flowers assumed their proper colour of fine yellow
spotted with crimson. An apparently authentic account has been
published[894] of two forms of Hemerocallis, which have been
universally considered as distinct species, changing into each other;
for the roots of the large-flowered tawny _H. fulva_, being divided and
planted in a different soil and place, produced the small-flowered
yellow _H. flava_, as well as some intermediate forms. It is doubtful
whether such cases as these latter, as well as the "flushing" of broken
tulips and the "running" of particoloured carnations,--that is, their
more or less complete return to a uniform tint,--ought to be classed
under bud-variation, or ought to be retained for the chapter in which I
treat of the direct action of the conditions of life on organic beings.
These cases, however, have this much in common with bud-variation, that
the change is effected through buds and not through seminal
reproduction. But, on the other hand, there is this difference--that in
ordinary cases of bud-variation, one bud alone changes, whilst in the
foregoing cases all the buds on the same plant were modified together;
yet we have an intermediate case, for with the potato all the eyes in
one tuber alone simultaneously changed their character.

I will conclude with a few allied cases, which may be ranked either
under bud-variation, or under the direct action of the conditions of
life. When the common Hepatica 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 different leaves and manner of growth, is a
surprising sight. The same raceme sometimes bears two kinds of flowers;
and I have seen a single flower exactly divided into halves, one side
being bright yellow and the other purple; so that one half of the
standard-petal was yellow and of larger size, and the other half purple
and smaller. In another flower the whole corolla was bright yellow, but
exactly half the calyx was purple. In another, one of the dingy-red
wing-petals had a bright yellow narrow stripe on it; and lastly, in
another flower, one of the stamens, which had become slightly
foliaceous, was half yellow and half purple; so that the tendency to
segregation of character or reversion affects even single parts {388}
and organs.[899] The most remarkable fact about this tree is that in
its intermediate state, even when growing near both parent-species, it
is quite sterile; but when the flowers become pure yellow or pure
purple they yield seed. I believe that the pods from the yellow flowers
yield a full complement of seed; they certainly yield a large number.
Two seedlings raised by Mr. Herbert from such seed[900] exhibited a
purple tinge on the stalks of their flowers; but several seedlings
raised by myself resembled in every character the common laburnum, with
the exception that some of them had remarkably long racemes: these
seedlings were perfectly fertile. That such purity of character and
fertility should be suddenly reacquired from so hybridized and sterile
a form is an astonishing phenomenon. The branches with purple flowers
appear at first sight exactly to resemble those of _C. purpureus_; but
on careful comparison I found that they differed from the pure species
in the shoots being thicker, the leaves a little broader, and the
flowers slightly shorter, with the corolla and calyx less brightly
purple: the basal part of the standard-petal also plainly showed a
trace of the yellow stain. So that the flowers, at least in this
instance, had not perfectly recovered their true character; and in
accordance with this, they were not perfectly fertile, for many of the
pods contained no seed, some produced one, and very few contained as
many as two seeds; whilst numerous pods on a tree of the pure _C.
purpureus_ in my garden contained three, four, and five fine seeds. The
pollen, moreover, was very imperfect, a multitude of grains being small
and shrivelled; and this is a singular fact; for, as we shall
immediately see, the pollen-grains in the dingy-red and sterile flowers
on the parent-tree, were, in external appearance, in a much better
state, and included very few shrivelled grain. Although the pollen of
the reverted purple flowers was in so poor a condition, the ovules were
well-formed, and, when mature, germinated freely with me. Mr. Herbert
also raised plants from seeds of the reverted purple flowers, and they
differed _very little_ from the usual state of _C. purpureus_; but this
expression shows that they had not perfectly recovered their proper
character.

Prof. Caspary has examined the ovules of the dingy-red and sterile
flowers in several plants of _C. adami_ on the Continent,[901] and
finds them generally monstrous. In three plants examined by me in
England, the ovules were likewise monstrous, the nucleus varying much
in shape, and projecting irregularly beyond the proper coats. The
pollen-grains, on the other hand, judging from their external
appearance, were remarkably good, and readily protruded their tubes. By
repeatedly counting, under the microscope, the proportional number of
bad grains, Prof. Caspary ascertained that only 2.5 per cent. were bad,
which is a less proportion than in the pollen of three pure species of
Cytisus in their cultivated state, viz. _C. purpureus_, _laburnum_, and
_alpinus_. Although the pollen of _C. adami_ is thus in appearance
good, it does not follow, according {389} to M. Naudin's
observations[902] on Mirabilis, that it would be functionally
effective. The fact of the ovules of _C. adami_ being monstrous, and
the pollen apparently sound, is all the more remarkable, because it is
opposed to what usually occurs not only with most hybrids,[903] but
with two hybrids in the same genus, namely in _C. purpureo-elongatus_,
and _C. alpino-laburnum_. In both these hybrids, the ovules, as
observed by Prof. Caspary and myself, were well-formed, whilst many of
the pollen-grains were ill-formed; in the latter hybrid 20.3 per cent.,
and in the former no less than 84.8 per cent. of the grains were
ascertained by Prof. Caspary to be bad. This unusual condition of the
male and female reproductive elements in _C. adami_ has been used by
Prof. Caspary as an argument against this plant being considered as an
ordinary hybrid produced from seed; but we should remember that with
hybrids the ovules have not been examined nearly so frequently as the
pollen, and they may be much oftener imperfect than is generally
supposed. Dr. E. Bornet, of Antibes, informs me (through Mr. J.
Traherne Moggridge) that with hybrid Cisti the ovarium is frequently
deformed, the ovules being in some cases quite absent, and in other
cases incapable of fertilisation.

* * * * *

Several theories have been propounded to account for the origin of _C.
adami_, and for the transformations which it undergoes. These
transformations have been attributed by some authors to simple
bud-variation; but considering the wide difference between _C.
laburnum_ and _purpureus_, both of which are natural species, and
considering the sterility of the intermediate form, this view may be
summarily rejected. We shall presently see that, with hybrid plants,
two different embryos may be developed within the same seed and cohere;
and it has been supposed that _C. adami_ might have thus originated. It
is known that when a plant with variegated leaves is budded on a plain
stock, the latter is sometimes affected, and it is believed by some
that the laburnum has been thus affected. Thus Mr. Purser states[904]
that a common laburnum-tree in his garden, into which three _grafts_ of
the _Cytisus purpureus_ had been inserted, gradually assumed the
character of _C. adami_; but more evidence and copious details would be
requisite to make so extraordinary a statement credible.

Many authors maintain that _C. adami_ is a hybrid produced in the
common way by seed, and that it has reverted by buds to its two
parent-forms. Negative results are of little value; but Reisseck,
Caspary, and I myself, tried in vain to cross _C. laburnum_ and
_purpureus_; when I fertilised the former with pollen of the latter, I
had the nearest approach to success, for pods were formed, but in
sixteen days after the withering of the flowers they fell off.
Nevertheless, the belief that _C. adami_ is a spontaneously produced
hybrid between these two species is strongly supported by the fact that
hybrids between these species and two others have spontaneously {390}
arisen. In a bed of seedlings from _C. elongatus_, which grew near to
_C. purpureus,_ and was probably fertilised by it, through the agency
of insects (for these, as I know by experiment, play an important part
in the fertilisation of the laburnum), the sterile hybrid _C.
purpureo-elongatus_ appeared.[905] Thus, also, Waterer's laburnum, the
_C. alpino-laburnum_,[906] spontaneously appeared, as I am informed by
Mr. Waterer, in a bed of seedlings.

On the other hand, we have a clear and distinct account given by M.
Adam, who raised the plant, to Poiteau,[907] showing that _C. adami_ is
not an ordinary hybrid. M. Adam inserted in the usual manner a shield
of the bark of _C. purpureus_ into a stock of _C. laburnum_; and the
bud lay dormant, as often happens, for a year; the shield then produced
many buds and shoots, one of which grew more upright and vigorous with
larger leaves than the shoots of _C. purpureus_, and was consequently
propagated. Now it deserves especial notice that these plants were sold
by M. Adam, as a variety of _C. purpureus_, before they had flowered;
and the account was published by Poiteau after the plants had flowered,
but before they had exhibited their remarkable tendency to revert into
the two parent-species. So that there was no conceivable motive for
falsification, and it is difficult to see how there could have been any
error. If we admit as true M. Adam's account, we must admit the
extraordinary fact that two distinct species can unite by their
cellular tissue, and subsequently produce a plant bearing leaves and
sterile flowers intermediate in character between the scion and stock,
and producing buds liable to reversion; in short, resembling in every
important respect a hybrid formed in the ordinary way by seminal
reproduction. Such plants, if really thus formed, might be called
graft-hybrids.

* * * * *

I will now give all the facts which I have been able to collect
illustrative of the above theories, not for the sake of merely throwing
light on the origin of _C. adami_, but to show in how many
extraordinary and complex methods one kind of plant may affect another,
generally in connection with bud-variation. The supposition that either
_C. laburnum_ or _purpureus_ produced by ordinary bud-variation the
intermediate and the other form, may, as already remarked, be
absolutely excluded, from the want of any evidence, from the great
amount of change thus implied, {391} and from the sterility of the
intermediate form. Nevertheless such cases as nectarines suddenly
appearing on peach-trees, occasionally with the fruit half-and-half in
nature,--moss-roses appearing on other roses, with the flowers divided
into halves, or striped with different colours,--and other such cases,
are closely analogous in the result produced, though not in origin,
with the case of _C. adami_.

A distinguished botanist, Mr. G. H. Thwaites,[908] has recorded a
remarkable case of a seed from _Fuchsia coccinea_ fertilised by _F.
fulgens_, which contained two embryos, and was "a true vegetable twin."
The two plants produced from the two embryos were "extremely different
in appearance and character," though both resembled other hybrids of
the same parentage produced at the same time. These twin plants "were
closely coherent, below the two pairs of cotyledon-leaves, into a
single cylindrical stem, so that they had subsequently the appearance
of being branches on one trunk." Had the two united stems grown up to
their full height, instead of dying, a curiously mixed hybrid would
have been produced; but even if some of the buds had subsequently
reverted to both parent-forms, the case, although more complex, would
not have been strictly analogous with that of _C. adami_. On the other
hand, a mongrel melon described by Sageret[909] perhaps did thus
originate; for the two main branches, which arose from two
cotyledon-buds, produced very different fruit,--on the one branch like
that of the paternal variety, and on the other branch to a certain
extent like that of the maternal variety, the melon of China.

The famous _bizzarria Orange_ offers a strictly parallel case to that
of _Cytisus adami_. The gardener who in 1644 in Florence raised this
tree, declared that it was a seedling which had been grafted; and after
the graft had perished, the stock sprouted and produced the bizzarria.
Gallesio, who carefully examined several living specimens and compared
them with the description given by the original describer P. Nato,[910]
states that the tree produces at the same time leaves, flowers, and
fruit, identical with the bitter orange and with the citron of
Florence, and likewise compound fruit with the two kinds either blended
together, both externally and internally, or segregated in various
ways. This tree can be propagated by cuttings, and retains its
diversified character. The so-called trifacial orange of Alexandria and
Smyrna[911] resembles in its general nature the bizzarria, but differs
from it in the _sweet_ orange and citron being blended together in the
same fruit, and separately produced on the same tree: nothing is known
of its origin. In regard to the bizzarria, many authors believe that it
is a graft-hybrid; Gallesio on the other hand thinks that it is an
ordinary hybrid, with the habit of partially reverting {392} by buds to
the two parent-forms; and we have seen in the last chapter that the
species in this genus often cross spontaneously.

Here is another analogous, but doubtful case. A writer in the
'Gardener's Chronicle'[912] states that an _AEsculus rubicunda_ in his
garden yearly produced on one of its branches "spikes of pale yellow
flowers, smaller in size and somewhat similar in colour to those of _AE.
flava_." If as the editor believes _AEsculus rubicunda_ is a hybrid
descended on one side from _AE. flava_, we have a case of partial
reversion to one of the parent-forms. If, as some botanists maintain,
_AE. rubicunda_ is not a hybrid, but a natural species, the case is one
of simple bud-variation.

The following facts show that hybrids produced from seed in the
ordinary way, certainly sometimes revert by buds to their parent-forms.
Hybrids between _Tropaeolum minus_ and _majus_[913] at first produced
flowers intermediate in size, colour, and structure between their two
parents; but later in the season some of these plants produced flowers
in all respects like those of the mother-form, mingled with flowers
still retaining the usual intermediate condition. A hybrid Cereus
between _C. speciosissimus_ and _phyllanthus_,[914] plants which are
widely different in appearance, produced for the first three years
angular, five-sided stems, and then some flat stems like those of _C.
phyllanthus_. Koelreuter also gives cases of hybrid Lobelias and
Verbascums, which at first produced flowers of one colour, and later in
the season flowers of a different colour.[915] Naudin[916] raised forty
hybrids from _Datura laevis_ fertilised by _D. stramonium_; and three of
these hybrids produced many capsules, of which a half, or quarter, or
lesser segment was smooth and of small size like the capsule of the
pure _D. laevis_, the remaining part being spinose and of larger size
like the capsule of the pure _D. stramonium_: from one of these
composite capsules, plants were raised which perfectly resembled both
parent-forms.