ON BUD-VARIATION, AND ON CERTAIN ANOMALOUS MODES OF REPRODUCTION AND
VARIATION.
BUD-VARIATION 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.
GRAFT-HYBRIDS.
ON THE SEGREGATION OF THE PARENTAL CHARACTERS IN SEMINAL HYBRIDS BY BUD-
VARIATION.
ON THE DIRECT OR IMMEDIATE ACTION OF FOREIGN POLLEN ON THE MOTHER-PLANT.
ON THE EFFECTS IN FEMALE ANIMALS OF A PREVIOUS 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, etc., 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 kingdom; but
it is probable that if compound animals, such as corals, etc., had been
subjected to a long course of domestication, they would have varied by
buds; for they resemble plants in many respects. For instance, 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. (11/1. Since
the publication of the first edition of this work, I have found that M.
Carriere, Chef des Pepinieres au Mus. d'Hist. Nat. in his excellent Essay
'Production et Fixation des Varietes' 1865 has given a list of bud-
variations far more extensive than mine; but as these relate chiefly to
cases occurring in France I have left my list as it stood, adding a few
facts from M. Carriere and others. Any one who wishes to study the subject
fully should refer to M. Carriere's Essay.) These cases prove that those
authors who, like Pallas, attribute all variability to the crossing either
of distinct races, or of distinct 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 a double-
flowered almond which suddenly produced fruit closely resembling true
peaches. I have also given 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 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. (11/2.
'Gardener's Chronicle' 1854 page 821.) 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." (11/3. Lindley 'Guide to Orchard' as quoted in
'Gardener's Chronicle' 1852 page 821. For the Early mignonne peach see
'Gardener's Chronicle' 1864 page 1251.)
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. (11/4. 'Transact. Hort. Soc.' volume 2 page 160.) Mr.
Rivers, of Sawbridgeworth, informs me (January 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. (11/5. See also 'Gardener's Chronicle' 1863 page
27.)
CHERRY (Prunus cerasus).
Mr. Knight has recorded (ibid) 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. (11/6.
'Gardener's Chronicle' 1852 page 821.) M. Carriere gives (page 37) numerous
analogous cases, and one of the same tree bearing three kinds of fruit.
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. (11/7. 'Gardener's Chronicle' 1852 page 629; 1856 page 648; 1864
page 986. Other cases are given by Braun 'Rejuvenescence' in 'Ray Soc. Bot.
Mem.' 1853 page 314.) 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. (11/8. 'Ampelographie' etc. 1849
page 71.) Here is another striking case given on the excellent authority of
M. Carriere (11/9. 'Gardener's Chronicle' 1866 page 970.): "a black Hamburg
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 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 (11/10. 'Gardener's
Chronicle' 1855 pages 597, 612.) 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. (11/11. 'Gardener's Chronicle' 1842 page
873; 1855 page 646. In the 'Chronicle' page 876 Mr. P. Mackenzie states
that the bush still continues to bear the three kinds of fruit, "although
they have not been every year alike.) 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.
(11/12. 'Revue Horticole' quoted in 'Gardener's Chronicle' 1844 page 87.)
Alexander Braun (11/13. 'Rejuvenescence in Nature' 'Bot. Memoirs Ray Soc.'
1853 page 314.) also has often seen branches on white currant-trees bearing
red berries.
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. (11/14. 'Comptes Rendus' tome 41 1855 page 804. The second
case is given on the authority of Gaudichaud ibid tome 34 1852 page 748.)
APPLE (Pyrus malus).
In Canada, a tree of the variety called Pound Sweet, produced (11/15. This
case is given in the 'Gardener's Chronicle' 1867 page 403.), between two of
its proper fruit, an apple which was well russeted, 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. M. Carriere (page 38) mentions an analogous
instance. I shall hereafter give 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. (11/16. 'Journal of Proc.
Linn. Soc.' volume 2 Botany page 131.)
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. (11/17. 'Gardener's Chronicle' 1847 page 207.) The
Pompon 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."
(11/18. Herbert 'Amaryllidaceae' 1838 page 369.)
Crataegus oxyacantha.
A dark pink hawthorn has been known to throw out a single tuft of pure
white blossoms (11/19. 'Gardener's Chronicle' 1843 page 391.); and Mr. A.
Clapham, nurseryman, of Bedford, 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.
A. indica is well known often to produce new varieties by buds. 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. (11/20.
Exhibited at Hort. Soc. London. Report in 'Gardener's Chronicle' 1844 page
337.)
HIBISCUS (Paritium tricuspis).
A seedling of this plant, when some years old, produced, at Saharunpore
(11/21. Mr. W. Bell 'Bot. Soc. of Edinburgh' May 1863.), some branches
"which bore leaves and flowers widely different from the normal form." "The
abnormal leaf is much less 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." Dr. King, who subsequently had charge of
these Gardens, informs me that a tree of Paritium tricuspis (probably the
very same plant) growing there, had a branch buried in the ground,
apparently by accident; and this branch changed its character wonderfully,
growing like a bush, and producing flowers and leaves, resembling in shape
those of another species, viz., P. tiliaceum. A small branch springing from
this bush near the ground, reverted to the parent-form. Both forms were
extensively propagated during several years by cuttings and kept perfectly
true.
Althaea rosea.
A double yellow Hollyhock 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. (11/22.
'Revue Horticole' quoted in 'Gardener's Chronicle' 1845 page 475.)
PELARGONIUM.
These highly cultivated plants seem eminently liable to bud-variation. I
will give only a few well-marked cases. Gartner has seen (11/23.
'Bastarderzeugung' 1849 s. 76.) a plant of P. zonale with a branch having
white edges, 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 (11/24. 'Journal of
Horticulture' 1861 page 336.) 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. (11/25. W.P. Ayres 'Gardener's
Chronicle' 1842 page 791.) 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. (11/26. W.P. Ayres ibid.) Here is a
better case of reversion: a variety produced from a complicated cross,
after having been propagated for five generations by seed, yielded by bud-
variation three very distinct varieties which were undistinguishable from
plants, "known to have been at some time ancestors of the plant in
question." (11/27. Dr. Maxwell Masters 'Pop. Science Review' July 1872 page
250.) 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 (11/28. 'Gardener's Chronicle'
1861 page 968.) 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 (11/29. Ibid 1861 page
945.); but one at least of these did not arise through bud-variation, but
is believed to be a seedling from Rollisson's Unique. (11/30. W. Paul
'Gardener's Chronicle' 1861 page 968.) There are, also, in the trade
(11/31. Ibid page 945.) two other slightly different varieties, of unknown
origin, of Rollisson's Unique: so that altogether we have a curiously
complex case of variation both by buds and seeds. (11/32. For other cases
of bud-variation in this same variety see 'Gardener's Chronicle' 1861 pages
578, 600, 925. For other distinct cases of bud-variation in the genus
Pelargonium see 'Cottage Gardener' 1860 page 194.) Here is a still more
complex case: M. Rafarin states that a pale rose-coloured variety produced
a branch bearing deep red flowers. "Cuttings were taken from this 'sport,'
from which 20 plants were raised, which flowered in 1867, when it was found
that scarcely two were alike." Some resembled the parent-form, some
resembled the sport, some bore both kinds of flowers; and even some of the
petals on the same flower were rose-coloured and others red. (11/33. Dr.
Maxwell Masters 'Pop. Science Review' July 1872 page 254.) 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. (11/34. Rev. W.T. Bree in Loudon's 'Gardener's Mag.' volume 8 1832
page 93.)
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. (11/35. 'The Chrysanthemum: its History and Culture'
by J. Salter 1865 page 41 etc.) A variety called cedo nulli bears small
yellow flowers, but habitually produces branches with white flowers; and a
specimen was exhibited, which Prof. T. Dyer saw, before the Horticultural
Society. 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 parti-coloured.
(11/36. Bree in Loudon's 'Gardener's Mag.' volume 8 1832 page 93.) The
flowers of Anthemis also vary on the same plant. (11/37. Bronn 'Geschichte
der Natur' b. 2 s. 123.)
ROSES.
Many varieties of the Rose are known or are believed to have originated by
bud-variation. (11/38. T. Rivers 'Rose Amateur's Guide' 1837 page 4.) The
common double moss-rose was imported into England from Italy about the year
1735. (11/39. Mr. Shailer quoted in 'Gardener's Chronicle' 1848 page 759.)
Its origin is unknown, but from analogy it probably arose from the Provence
rose (R. centifolia) by bud-variation; for the 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. (11/40. 'Transact. Hort. Soc.' volume 4 1822
page 137; 'Gardener's Chronicle' 1842 page 422.) Mr. Rivers also informs me
that he raised two or three roses of the Provence class from seed of the
old single moss-rose (11/41. See also Loudon's 'Arboretum' volume 2 page
780.); 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." (11/42. All these statements on the origin of the
several varieties of the moss-rose are given on the authority of Mr.
Shailer, who, together with his father, was concerned in their original
propagation. See 'Gard. Chronicle' 1852 page 759.) A white moss-rose has
been seen to bear a flower half white and half pink. (11/43. 'Gardener's
Chronicle' 1845 page 564.) 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 de Meaux moss-rose (also a variety of R. centifolia) (11/44.
'Transact. Hort. Soc.' volume 2 page 242.) having appeared as a sporting
branch on the common rose de Meaux. Prof. Caspary has carefully described
(11/45. 'Shriften der Phys. Oekon. Gesell. zu Konigsberg' February 3, 1865
s. 4. See also Dr. Caspary's paper in 'Transactions of the Hort. Congress
of Amsterdam' 1865.) 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 originated in this way. (11/46. 'Gardener's
Chronicle' 1852 page 759.) M. Carriere states (page 36) that he himself
knows of five varieties thus produced by the Baronne Prevost. The double
and highly-coloured Belladonna rose has produced by suckers both semi-
double and almost single white roses (11/47. 'Transact. Hort. Soc.' volume
2 page 242.); whilst suckers from one of these semi-double white roses
reverted to perfectly characterised Belladonnas. In St. Domingo, varieties
of the China rose propagated by cuttings often revert after a year or two
into the old China rose. (11/48. Sir R. Schomburgk 'Proc. Linn. Soc. Bot.'
volume 2 page 132.) Many cases 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 (11/49. 'Gardener's Chronicle' 1862 page 619.), 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 (11/50. Hopkirk 'Flora Anomala' 167.) 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
(11/51. 'Sur La Production et la Fixation des Varietes' 1865 page 4.), 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 (11/52. 'Journal of Horticulture' March 1865 page 233.) 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, etc.) occasionally vary by layers; and some kinds are so
little certain in character that they are called by floriculturists "catch-
flowers." (11/53. 'Gardener's Chronicle' 1843 page 135.) 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." (11/54. Ibid 1842 page 55.) 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; and many
others 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 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 (11/55.
'Gardener's Chronicle' 1867 page 235.) 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 (11/56. Gartner
'Bastarderzeugung' s. 305.) bearing flowers of three different colours. The
hybrid Gladiolus colvilii occasionally bears uniformly coloured flowers,
and one case is recorded (11/57. Mr. D. Beaton in 'Cottage Gardener' 1860
page 250.) of all the flowers on a plant thus changing colour. A Fuchsia
has been seen (11/58. 'Gardener's Chronicle' 1850 page 536.) 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. (11/59. Braun 'Ray Soc.
Bot. Mem.' 1853 page 315; Hopkirk 'Flora Anomala' page 164; Lecoq
'Geograph. Bot. de l'Europe' tome 3 1854 page 405; and 'De la Fecondation'
1862 page 303.) 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; incidentally some remarkable modifications in the leaves and
shoots of the rose and Paritium, 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 (11/60. 'Des Varietes' 1865
page 5.) states that on Aralia trifoliata, which properly has leaves with
three leaflets, branches frequently appear bearing simple leaves of various
forms; these can be propagated by buds or by 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. (11/61. W. Mason in 'Gardener's Chronicle' 1843 page
878.) 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 forms. (11/62. Alex. Braun 'Ray
Soc. Bot. Mem.' 1853 page 315; 'Gardener's Chron.' 1841 page 329.) 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 heterophyllus 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. (11/63. Dr. M.T. Masters 'Royal
Institution Lecture' March 16, 1860.)
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
often 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. (11/64.
See Mr. W.K. Bridgeman's curious paper in 'Annals and Mag. of Nat. Hist.'
December 1861; also Mr. J. Scott 'Bot. Soc. Edinburgh' June 12, 1862.)
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. (11/65. 'Journal of Horticulture' 1861
page 336; Verlot 'Des Varietes' page 76.) 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. (11/66. See also Verlot 'Des Varietes'
page 74.) 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, etc.; 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 variety hardly ever changes." (11/67.
'Gardener's Chron.' 1844 page 86.) 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
still remains. (11/68. Ibid 1861 page 963.) It is remarkable that plants
propagated from branches which have reverted from variegated to plain
leaves (11/69. Ibid 1861 page 433; 'Cottage Gardener' 1860 page 2.) 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 (11/70. M. Lemoine quoted in
'Gardener's Chronicle' 1867 page 74 has lately observed that the Symphytum
with variegated leaves cannot be propagated by division of the roots. He
also found that out of 500 plants of a Phlox with striped flowers, which
had been propagated by root-division, only seven or eight produced striped
flowers. See also on striped Pelargoniums 'Gardener's Chronicle' 1867 page
1000.); 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. (11/71. Anderson 'Recreations in Agriculture' volume 5 page 152.) My
father repeatedly tried this experiment, and always with the same result. I
may here mention that maize and wheat sometimes produce new varieties from
the stock or root, as does the sugar-cane. (11/72. For wheat see
'Improvement of the Cereals' by P. Shirreff 1873 page 47. For maize and
sugar-cane Carriere ibid pages 40, 42. With respect to the sugar-cane Mr.
J. Caldwell of Mauritius says ('Gardener's Chronicle' 1874 page 316) the
Ribbon cane has here "sported into a perfectly green cane and a perfectly
red cane from the same head. I verified this myself, and saw at least 200
instances in the same plantation, and the fact has completely upset all our
preconceived ideas of the difference of colour being permanent. The
conversion of a striped cane into a green cane was not uncommon, but the
change into a red cane universally disbelieved, and that both events should
occur in the same plant incredible. I find, however, in Fleischman's
'Report on Sugar Cultivation in Louisiana for 1848 by the American Patent
Office, the circumstance is mentioned, but he says he never saw it
himself.")
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 old
FORTY-FOLD POTATO, which is a purple variety, was observed (11/73.
'Gardener's Chronicle' 1857 page 662.) 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. (11/74. 'Gard. Chronicle' 1841 page 814.)
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. (11/75. Ibid 1857 page 613.) Several cases
have been recorded of large portions of whole rows of potatoes slightly
changing their character. (11/76. Ibid 1857 page 679. See also Philips
'Hist. of Vegetables' volume 2 page 91 for other and similar accounts.)
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." (11/77.
'Journal of Proc. Linn. Soc.' volume 2 Botany page 132.) 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." (11/78. Loudon's 'Gardener's Mag.' volume 8 1832 page 94.)
Another case is described of a dahlia with purple flowers which bore a
white flower streaked with purple. (11/79. 'Gard. Chronicle' 1850 page 536;
and 1842 page 729.)
Considering how long and extensively many Bulbous plants have been
cultivated, and how numerous are the varieties produced from seed, these
plants have not perhaps varied so much by offsets,--that is, by the
production of new bulbs,--as might have been expected. With the Hyacinth,
however, several instances have been given by M. Carriere. A case also has
been recorded of a blue variety which for three successive years gave
offsets producing white flowers with a red centre. (11/80. 'Des Jacinthes'
etc. Amsterdam 1768 page 122.) Another hyacinth bore (11/81. 'Gardener's
Chronicle' 1845 page 212.) on the same truss a perfectly pink and a
perfectly blue flower. I have seen a bulb producing at the same time one
stalk or truss with fine blue flowers, another with fine red flowers, and a
third with blue flowers on one side and red on the other; several of the
flowers being also longitudinally striped red and blue.
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." (11/82. Loudon's 'Encyclopaedia of Gardening' page
1024.) The broken or variegated colours which give value to all tulips are
due to bud-variation; for although the 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 (11/83. 'Production
des Varietes' 1865 p. 63.) 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 (11/84. 'Gardener's Chronicle' 1841 page 782; 1842 page
55.) 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. Iris xiphium, according to M. Carriere (page 65), behaves in
nearly the same manner, as do so many tulips.
During two consecutive years all the early flowers in a bed of Tigridia
conchiflora (11/85. 'Gardener's Chron.' 1849 page 565.) 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 (11/86. 'Transact. Lin. Soc.' volume 2 page 354.) 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 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 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. With the potato, we have
seen an intermediate case, for all the eyes in one tuber 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. (11/87. Godron 'De l'Espece'
tome 2 page 84.) 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 fruit-trees undergo from
being grafted and regrafted on various stocks (11/88. M. Carriere has
lately described in the 'Revue Horticole' December 1, 1866 page 457, an
extraordinary case. He twice inserted grafts of the Aria vestita on thorn-
trees (epines) growing in pots; and the grafts, as they grew, produced
shoots with bark, buds, leaves, petioles, petals, and flower-stalks, all
widely different from those of the Aria. The grafted shoots were also much
hardier, and flowered earlier, than those on the ungrafted Aria.) were
considered by Andrew Knight (11/89. 'Transact. Hort. Soc.' volume 2 page
160.) 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, whilst they
closely resemble each other in old age; and as with certain oaks, and with
some varieties of the lime and hawthorn. (11/90. For the cases of oaks see
Alph. De Candolle in 'Bibl. Univers.' Geneva November 1862; for limes etc.
Loudon's 'Gard. Mag.' volume 11 1835 page 503.)]
GRAFT-HYBRIDS.
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 the two
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 narrow
bright yellow 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 and organs. (11/91. For analogous facts see Braun
'Rejuvenescence' in 'Ray Soc. Bot. Mem.' 1853 page 320; and 'Gardener's
Chronicle' 1842 page 397; also Braun in 'Sitzungsberichte der Ges.
naturforschender Freunde' June 1873 page 63.) 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
larger number. Two seedlings raised by Mr. Herbert from such seed (11/92.
'Journal of Hort. Soc.' volume 2 1847 page 100.) 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 hybridised 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
grains. Although the pollen of the reverted purple flowers was in so poor a
condition, the ovules were well formed, and the seeds, when mature,
germinated freely with me. Mr. Herbert raised plants from seeds of the
reverted purple flowers, and they differed a VERY LITTLE from the usual
state of C. purpureus. Some which I raised in the same manner did not
differ at all, either in the character of their flowers or of the whole
bush, from the pure C. purpureus. Prof. Caspary has examined the ovules of
the dingy-red and sterile flowers in several plants of C. adami on the
Continent (11/93. See 'Transact. of Hort. Congress of Amsterdam' 1865; but
I owe most of the following information to Prof. Caspary's letters.) 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 to M.
Naudin's observation (11/94. 'Nouvelles Archives du Museum' tome 1 page
143.) 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 (11/95. See on this head Naudin ibid page 141.), 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. The whole case has
been attributed by some authors to 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 embryos differing in their characters may be developed within the same
seed and cohere; and it has been supposed that C. adami thus originated.
Many botanists 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 not of much value; but Reisseck, Caspary, and 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 supported by the
fact that such hybrids have arisen in this genus. 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. (11/96. Braun in 'Bot.
Mem. Ray. Soc.' 1853 page 23.) Thus, also, Waterer's laburnum, the C.
alpino-laburnum (11/97. This hybrid has never been described. It is exactly
intermediate in foliage, time of flowering, dark striae at the base of the
standard petal, hairiness of the ovarium, and in almost every other
character, between C. laburnum and alpinus; but it approaches the former
species more nearly in colour, and exceeds it in the length of the racemes.
We have before seen that 20.3 per cent of its pollen-grains are ill-formed
and worthless. My plant, though growing not above thirty or forty yards
from both parent-species, during some seasons yielded no good seeds; but in
1866 it was unusually fertile, and its long racemes produced from one to
occasionally even four pods. Many of the pods contained no good seeds, but
generally they contained a single apparently good seed, sometimes two, and
in one case three seeds. Some of these seeds germinated, and I raised two
trees from them; one resembles the present form; the other has a remarkable
dwarf character with small leaves, but has not yet flowered.) 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 to Poiteau
(11/98. 'Annales de la Soc. de l'Hort. de Paris' tome 7 1830 page 93.) by
M. Adam, who raised the plant, showing that C. adami is not an ordinary
hybrid; but is what may be called a graft-hybrid, that is, one produced
from the united cellular tissue of two distinct species. 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. (11/99. An account was given in the 'Gardener's Chronicle' 1857
pages 382, 400, of a common laburnum on which grafts of C. purpureus had
been inserted, and which gradually assumed the character of C. adami; but I
have little doubt that C. adami had been sold to the purchaser, who was not
a botanist, in the place of C. purpureus. I have ascertained that this
occurred in another instance.) 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.]
I will therefore give all the facts which I have been able to collect on
the formation of hybrids between distinct species or varieties, without the
intervention of the sexual organs. For if, as I am now convinced, this is
possible, it is a most important fact, which will sooner or later change
the views held by physiologists with respect to sexual reproduction. A
sufficient body of facts will afterwards be adduced, showing that the
segregation or separation of the characters of the two parent-forms by bud-
variation, as in the case of Cytisus adami, is not an unusual though a
striking phenomenon. We shall further see that a whole bud may thus revert,
or only half, or some smaller segment.
[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 (11/100. Gallesio 'Gli
Agrumi dei Giard. Bot. Agrar. di. Firenze' 1839 page 11. In his 'Traite du
Citrus' 1811 page 146, he speaks as if the compound fruit consisted in part
of a lemon, but this apparently was a mistake.), 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 (11/101. 'Gardener's Chron.' 1855 page 628. See also
Prof. Caspary in 'Transact. Hort. Congress of Amsterdam' 1865.) resembles
in its general nature the bizzarria, and differs only in the orange being
of the sweet kind; this and the citron are blended together in the same
fruit, or are 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 by buds to the two parent-
forms; and we have seen that the species in this genus often cross
spontaneously.
It is notorious that when the variegated Jessamine is budded on the common
kind, the stock sometimes produces buds bearing variegated leaves: Mr.
Rivers, as he informs me, has seen instances of this. The same thing occurs
with the Oleander. (11/102. Gartner 'Bastarderzeugung' s. 611 gives many
references on this subject.) Mr. Rivers, on the authority of a trustworthy
friend, states that some buds of a golden-variegated ash, which were
inserted into common ashes, all died except one; but the ash-stocks were
affected (11/103. A nearly similar account was given by Brabley in 1724 in
his 'Treatise on Husbandry' volume 1 page 199.) and produced, both above
and below the points of insertion of the plates of bark bearing the dead
buds, shoots which bore variegated leaves. Mr. J. Anderson Henry has
communicated to me a nearly similar case: Mr. Brown, of Perth, observed
many years ago, in a Highland glen, an ash-tree with yellow leaves; and
buds taken from this tree were inserted into common ashes, which in
consequence were affected, and produced the Blotched Breadalbane Ash. This
variety has been propagated, and has preserved its character during the
last fifty years. Weeping ashes, also, were budded on the affected stocks,
and became similarly variegated. It has been repeatedly proved that several
species of Abutilon, on which the variegated A. thompsonii has been
grafted, become variegated. (11/104. Morren 'Bull. de l'Acad. R. des
Sciences de Belgique' 2de series tome 28 1869 page 434. Also Magnus
'Gesellschaft naturforschender Freunde, Berlin' February 21, 1871 page 13;
ibid June 21, 1870 and October 17, 1871. Also 'Bot. Zeitung' February 24,
1871.)