The species have varied both by seed and by bud; such modified buds being often called by gardeners sports. In the following chapter I shall fully discuss this latter subject, and shall show that bud-variations can be propagated not only by grafting and budding, but often by seed. Whenever a new rose appears with any peculiar character, however produced, if it yields seed, Mr. Rivers (page 4) fully expects it to become the parent-type of a new family. The tendency to vary is so strong in some kinds, as in the Village Maid (Rivers page 16), that when grown in different soils it varies so much in colour that it has been thought to form several distinct kinds.
Altogether the number of kinds is very great: thus M. Desportes, in his Catalogue for 1829, enumerates 2562 as cultivated in France; but no doubt a large proportion of these are merely nominal.
It would be useless to specify the many points of difference between the various kinds, but some const.i.tutional peculiarities may be mentioned.
Several French roses (Rivers page 12) will not succeed in England; and an excellent horticulturist (10/179. The Rev. W.F. Radclyffe in "Journal of Horticulture" March 14, 1865 page 207.) remarks, that "Even in the same garden you will find that a rose that will do nothing under a south wall will do well under a north one. That is the case with Paul Joseph here. It grows strongly and blooms beautifully close to a north wall. For three years seven plants have done nothing under a south wall." Many roses can be forced, "many are totally unfit for forcing, among which is General Jacqueminot." (10/180. "Gardener"s Chronicle" 1831 page 46.) From the effects of crossing and variation Mr. Rivers enthusiastically antic.i.p.ates (page 87) that the day will come when all our roses, even moss-roses, will have evergreen foliage, brilliant and fragrant flowers, and the habit of blooming from June till November. "A distant view this seems, but perseverance in gardening will yet achieve wonders," as a.s.suredly it has already achieved wonders.
It may be worth while briefly to give the well-known history of one cla.s.s of roses. In 1793 some wild Scotch roses (R. spinosissima) were transplanted into a garden (10/181. Mr. Sabine in "Transact. Hort. Soc."
volume 4 page 285.); and one of these bore flowers slightly tinged with red, from which a plant was raised with semi-monstrous flowers, also tinged with red; seedlings from this flower were semi-double, and by continued selection, in about nine or ten years, eight sub-varieties were raised. In the course of less than twenty years these double Scotch roses had so much increased in number and kind, that twenty-six well-marked varieties, cla.s.sed in eight sections, were described by Mr. Sabine. In 1841 (10/182.
"An Encyclop. of Plants" by J.C. Loudon 1841 page 443.) it is said that three hundred varieties could be procured in the nursery-gardens near Glasgow; and these are described as blush, crimson, purple, red, marbled, two-coloured, white, and yellow, and as differing much in the size and shape of the flower.
PANSY OR HEARTSEASE (Viola tricolor, etc.).
The history of this flower seems to be pretty well known; it was grown in Evelyn"s garden in 1687; but the varieties were not attended to till 1810- 1812, when Lady Monke, together with Mr. Lee, the well-known nursery-man, energetically commenced their culture; and in the course of a few years twenty varieties could be purchased. (10/183. Loudon"s "Gardener"s Magazine" volume 11 1835 page 427; also Journal of Horticulture" April 14, 1863 page 275.) At about the same period, namely in 1813 or 1814, Lord Gambier collected some wild plants, and his gardener, Mr. Thomson, cultivated them, together with some common garden varieties, and soon effected a great improvement. The first great change was the conversion of the dark lines in the centre of the flower into a dark eye or centre, which at that period had never been seen, but is now considered one of the chief requisites of a first-rate flower. In 1835 a book entirely devoted to this flower was published, and four hundred named varieties were on sale. From these circ.u.mstances this plant seemed to me worth studying, more especially from the great contrast between the small, dull, elongated, irregular flowers of the wild pansy, and the beautiful, flat, symmetrical, circular, velvet-like flowers, more than two inches in diameter, magnificently and variously coloured, which are exhibited at our shows. But when I came to enquire more closely, I found that, though the varieties were so modern, yet that much confusion and doubt prevailed about their parentage. Florists believe that the varieties (10/184. Loudon"s "Gardener"s Magazine" volume 8 page 575: volume 9 page 689.) are descended from several wild stocks, namely, V. tricolor, lutea, grandiflora, amoena, and altaica, more or less intercrossed. And when I looked to botanical works to ascertain whether these forms ought to be ranked as species, I found equal doubt and confusion. Viola altaica seems to be a distinct form, but what part it has played in the origin of our varieties I know not; it is said to have been crossed with V. lutea. Viola amoena (10/185. Sir J.E. Smith "English Flora"
volume 1 page 306. H.C. Watson "Cybele Britannica" volume 1 1847 page 181.) is now looked at by all botanists as a natural variety of V. grandiflora; and this and V. sudetica have been proved to be identical with V. lutea.
The latter and V. tricolor (including its admitted variety V. arvensis) are ranked as distinct species by Babington, and likewise by M. Gay (10/186.
Quoted from "Annales des Sciences" in the Companion to the "Bot. Mag."
volume 1 1835 page 159.) who has paid particular attention to the genus; but the specific distinction between V. lutea and tricolor is chiefly grounded on the one being strictly and the other not strictly perennial, as well as on some other slight and unimportant differences in the form of the stem and stipules. Bentham unites these two forms; and a high authority on such matters, Mr. H.C. Watson (10/187. "Cybele Britannica" volume 1 page 173. See also Dr. Herbert on the changes of colour in transplanted specimens, and on the natural variations of V. grandiflora, in "Transact.
Hort. Soc." volume 4 page 19.) says that, "while V. tricolor pa.s.ses into V.
arvensis on the one side, it approximates so much towards V. lutea and V.
Curtisii on the other side, that a distinction becomes scarcely more easy between them."
Hence, after having carefully compared numerous varieties, I gave up the attempt as too difficult for any one except a professed botanist. Most of the varieties present such inconstant characters, that when grown in poor soil, or when flowering out of their proper season, they produced differently coloured and much smaller flowers. Cultivators speak of this or that kind as being remarkably constant or true; but by this they do not mean, as in other cases, that the kind transmits its character by seed, but that the individual plant does not change much under culture. The principle of inheritance, however, does hold good to a certain extent even with the fleeting varieties of the Heartsease, for to gain good sorts it is indispensable to sow the seed of good sorts. Nevertheless, in almost every large seed-bed a few, almost wild seedlings reappear through reversion. On comparing the choicest varieties with the nearest allied wild forms, besides the difference in the size, outline, and colour of the flowers, the leaves sometimes differ in shape, as does the calyx occasionally in the length and breadth of the sepals. The differences in the form of the nectary more especially deserve notice; because characters derived from this organ have been much used in the discrimination of most of the species of Viola. In a large number of flowers compared in 1842 I found that in the greater number the nectary was straight; in others the extremity was a little turned upwards, or downwards, or inwards, so as to be completely hooked; in others, instead of being hooked, it was first turned rectangularly downwards, and then backwards and upwards; in others, the extremity was considerably enlarged; and lastly, in some the basal part was depressed, becoming, as usual, laterally compressed towards the extremity.
In a large number of flowers, on the other hand, examined by me in 1856 from a nursery-garden in a different part of England, the nectary hardly varied at all. Now M. Gay says that in certain districts, especially in Auvergne, the nectary of the wild V. grandiflora varies in the manner just described. Must we conclude from this that the cultivated varieties first mentioned were all descended from V. grandiflora, and that the second lot, though having the same general appearance, were descended from V. tricolor, of which the nectary, according to M. Gay, is subject to little variation?
Or is it not more probable that both these wild forms would be found under other conditions to vary in the same manner and degree, thus showing that they ought not to be ranked as specifically distinct?
THE DAHLIA
The Dahlia has been referred to by almost every author who has written on the variation of plants, because it is believed that all the varieties are descended from a single species, and because all have arisen since 1802 in France, and since 1804 in England. (10/188. Salisbury in "Transact. Hort.
Soc." volume 1 1812 pages 84, 92. A semi-double variety was produced in Madrid in 1790.) Mr. Sabine remarks that "it seems as if some period of cultivation had been required before the fixed qualities of the native plant gave way and began to sport into those changes which now so delight us." (10/189. "Transact. Hort. Soc." volume 3 1820 page 225.) The flowers have been greatly modified in shape from a flat to a globular form. Anemone and ranunculus-like races (10/190. Loudon"s "Gardener"s Mag." volume 6 1830 page 77.) which differ in the form and arrangement of the florets, have arisen; also dwarfed races, one of which is only eighteen inches in height.
The seeds vary much in size. The petals are uniformly coloured or tipped or striped, and present an almost infinite diversity of tints. Seedlings of fourteen different colours (10/191. Loudon"s "Encyclop. of Gardening" page 1035.) have been raised from the same plant; yet, as Mr. Sabine has remarked, "many of the seedlings follow their parents in colour." The period of flowering has been considerably hastened, and this has probably been effected by continued selection. Salisbury, writing 1808, says that they then flowered from September to November; in 1828 some new dwarf varieties began flowering in June (10/192. "Transact. Hort. Soc." volume 1 page 91; and Loudon"s "Gardener"s Mag." volume 3 1828 page 179.); and Mr.
Grieve informs me that the dwarf purple Zelinda in his garden is in full bloom by the middle of June and sometimes even earlier. Slight const.i.tutional differences have been observed between certain varieties: thus, some kinds succeed much better in one part of England than in another (10/193. Mr. Wildman in "Gardener"s Chronicle" 1843 page 87. "Cottage Gardener" April 8, 1856 page 33.) and it has been noticed that some varieties require much more moisture than others. (10/194. M. Faivre has given an interesting account of the successive variations of the Chinese primrose, since its introduction into Europe about the year 1820: "Revue des Cours Scientifiques" June 1869 page 428.)
Such flowers as the CARNATION, COMMON TULIP, and HYACINTH, which are believed to be descended, each from a single wild form, present innumerable varieties, differing almost exclusively in the size, form, and colour of the flowers. These and some other anciently cultivated plants which have been long propagated by offsets, pipings, bulbs, etc., become so excessively variable, that almost each new plant raised from seed forms a new variety, "all of which to describe particularly," as old Gerarde wrote in 1597, "were to roll Sisyphus"s stone, or to number the sands."
HYACINTH (Hyacinthus orientalis).
It may, however, be worth while to give a short account of this plant, which was introduced into England in 1596 from the Levant. (10/195. The best and fullest account of this plant which I have met with is by a famous horticulturist, Mr. Paul, of Waltham, in the "Gardener"s Chronicle" 1864 page 342.) The petals of the original flower, says Mr. Paul, were narrow, wrinkled, pointed, and of a flimsy texture; now they are broad, smooth, solid, and rounded. The erectness, breadth, and length of the whole spike, and the size of the flowers, have all increased. The colours have been intensified and diversified. Gerarde, in 1597, enumerates four, and Parkinson, in 1629, eight varieties. Now the varieties are very numerous, and they were still more numerous a century ago. Mr. Paul remarks that "it is interesting to compare the Hyacinths of 1629 with those of 1864, and to mark the improvement. Two hundred and thirty-five years have elapsed since then, and this simple flower serves well to ill.u.s.trate the great fact that the original forms of nature do not remain fixed and stationary, at least when brought under cultivation. While looking at the extremes, we must not, however, forget that there are intermediate stages which are for the most part lost to us. Nature will sometimes indulge herself with a leap, but as a rule her march is slow and gradual." He adds that the cultivator should have "in his mind an ideal of beauty, for the realisation of which he works with head and hand." We thus see how clearly Mr. Paul, an eminently successful cultivator of this flower, appreciates the action of methodical selection.
In a curious and apparently trustworthy treatise, published at Amsterdam (10/196. "Des Jacinthes, de leur Anatomie, Reproduction, et Culture"
Amsterdam 1768.) in 1768, it is stated that nearly 2,000 sorts were then known; but in 1864 Mr. Paul found only 700 in the largest garden at Haarlem. In this treatise it is said that not an instance is known of any one variety reproducing itself truly by seed: the white kinds, however, now (10/197. Alph. de Candolle "Geograph. Bot." page 1082.) almost always yield white hyacinths, and the yellow kinds come nearly true. The hyacinth is remarkable from having given rise to varieties with bright blue, pink, and distinctly yellow flowers. These three primary colours do not occur in the varieties of any other species; nor do they often all occur even in the distinct species of the same genus. Although the several kinds of hyacinths differ but slightly from each other except in colour, yet each kind has its own individual character, which can be recognised by a highly educated eye; thus the writer of the Amsterdam treatise a.s.serts (page 43) that some experienced florists, such as the famous G. Voorhelm, seldom failed in a collection of above twelve hundred sorts to recognise each variety by the bulb alone! This same writer mentions some few singular variations: for instance, the hyacinth commonly produces six leaves, but there is one kind (page 35) which scarcely ever has more than three leaves; another never more than five; whilst others regularly produce either seven or eight leaves. A variety, called la Coryphee, invariably produces (page 116) two flower-stems, united together and covered by one skin. The flower-stem in another kind (page 128) comes out of the ground in a coloured sheath, before the appearance of the leaves, and is consequently liable to suffer from frost. Another variety always pushes a second flower-stem after the first has begun to develop itself. Lastly, white hyacinths with red, purple, or violet centres (page 129) are the most liable to rot. Thus, the hyacinth, like so many previous plants, when long cultivated and closely watched, is found to offer many singular variations.]
In the two last chapters I have given in some detail the range of variation, and the history, as far as known, of a considerable number of plants, which have been cultivated for various purposes. But some of the most variable plants, such as Kidney-beans, Capsic.u.m, Millets, Sorghum, etc., have been pa.s.sed over; for botanists are not at all agreed which kinds ought to rank as species and which as varieties; and the wild parent- species are unknown. (10/198. Alph. De Candolle "Geograph. Bot." page 983.) Many plants long cultivated in tropical countries, such as the Banana, have produced numerous varieties; but as these have never been described with even moderate care, they are here also pa.s.sed over. Nevertheless, a sufficient, and perhaps more than sufficient, number of cases have been given, so that the reader may be enabled to judge for himself on the nature and great amount of variation which cultivated plants have undergone.
CHAPTER 1.XI.
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 s.e.xual 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 s.e.xual 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 pa.s.s 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 a.n.a.logy 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 a.n.a.logous 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 cl.u.s.ter. (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.