Since Knight's time there is abundant and additional evidence (10/103. See an account by Prof. Decaisne, and by others in 'Gardener's Chronicle' 1862 page 335 and 1858 page 172; and Mr. Barnet's paper in 'Hort. Soc. Transact.' volume 6 1826 page 170.) of the extent to which the American forms spontaneously cross. We owe indeed to such crosses most of our choicest existing varieties. Knight did not succeed in crossing the European wood-strawberry with the American Scarlet or with the Hautbois. Mr. Williams of Pitmaston, however, succeeded; but the hybrid offspring from the Hautbois, though fruiting well, never produced seed, with the exception of a single one, which reproduced the parent hybrid form. (10/104. 'Transact. Hort. Soc.' volume 5 1824 page 294.) Major R. Trevor Clarke informs me that he crossed two members of the Pine class (Myatt's B. Queen and Keen's Seedling) with the wood and hautbois, and that in each case he raised only a single seedling; one of these fruited, but was almost barren. Mr. W. Smith, of York, has raised similar hybrids with equally poor success. (10/105. 'Journal of Horticulture' December 30, 1862 page 779. See also Mr. Prince to the same effect ibid 1863 page 418.) We thus see (10/106. For additional evidence see 'Journal of Horticulture' December 9, 1862 page 721.) that the European and American species can with some difficulty be crossed; but it is improbable that hybrids sufficiently fertile to be worth cultivation will ever be thus produced. This fact is surprising, as these forms structurally are not widely distinct, and are sometimes connected in the districts where they grow wild, as I hear from Professor Asa Gray, by puzzling intermediate forms.
The energetic culture of the Strawberry is of recent date, and the cultivated varieties can in most cases be classed under some one of the above native stocks. As the American strawberries cross so freely and spontaneously, we can hardly doubt that they will ultimately become inextricably confused. We find, indeed, that horticulturists at present disagree under which class to rank some few of the varieties; and a writer in the 'Bon Jardinier' of 1840 remarks that formerly it was possible to class all of them under some one species, but that now this is quite impossible with the American forms, the new English varieties having completely filled up the gaps between them. (10/107. 'Le Fraisier' par le Comte L. de Lambertye pages 221, 230.) The blending together of two or more aboriginal forms, which there is every reason to believe has occurred with some of our anciently cultivated productions, we see now actually occurring with our strawberries.
The cultivated species offer some variations worth notice. The Black Prince, a seedling from Keen's Imperial (this latter being a seedling of a very white strawberry, the white Carolina), is remarkable from "its peculiar dark and polished surface, and from presenting an appearance entirely unlike that of any other kind." (10/108. 'Transact. Hort. Soc.' volume 6 page 200.) Although the fruit in the different varieties differs so greatly in form, size, colour, and quality, the so-called seed (which corresponds with the whole fruit in the plum) with the exception of being more or less deeply embedded in the pulp, is, according to De Jonghe (10/109. 'Gardener's Chronicle' 1858 page 173.) absolutely the same in all: and this no doubt may be accounted for by the seed being of no value, and consequently not having been subjected to selection. The strawberry is properly three-leaved, but in 1761 Duchesne raised a single-leaved variety of the European wood-strawberry, which Linnaeus doubtfully raised to the rank of a species. Seedlings of this variety, like those of most varieties not fixed by long-continued selection, often revert to the ordinary form, or present intermediate states. (10/110. Godron 'De l'Espece' tome 1 page 161.) A variety raised by Mr. Myatt (10/111. 'Gardener's Chronicle' 1851 page 440.), apparently belonging to one of the American forms presents a variation of an opposite nature, for it has five leaves; Godron and Lambertye also mention a five-leaved variety of F. collina.
The Red Bush Alpine strawberry (one of the F. vesca section) does not produce stolons or runners, and this remarkable deviation of structure is reproduced truly by seed. Another sub-variety, the White Bush Alpine, is similarly characterised, but when propagated by seed it often degenerates and produces plants with runners. (10/112. F. Gloede in 'Gardener's Chronicle' 1862 page 1053.) A strawberry of the American Pine section is also said to make but few runners. (10/113. Downing 'Fruits' page 532.)
Much has been written on the sexes of strawberries; the true Hautbois properly bears the male and female organs on separate plants (10/114. Barnet in 'Hort. Transact.' volume 6 page 210.), and was consequently named by Duchesne dioica; but it frequently produces hermaphrodites; and Lindley (10/115. 'Gardener's Chronicle' 1847 page 539.), by propagating such plants by runners, at the same time destroying the males, soon raised a self- prolific stock. The other species often showed a tendency towards an imperfect separation of the sexes, as I have noticed with plants forced in a hot-house. Several English varieties, which in this country are free from any such tendency, when cultivated in rich soils under the climate of North America (10/116. For the several statements with respect to the American strawberries see Downing 'Fruits' page 524; 'Gardener's Chronicle' 1843 page 188; 1847 page 539; 1861 page 717.) commonly produce plants with separate sexes. Thus a whole acre of Keen's Seedlings in the United States has been observed to be almost sterile from the absence of male flowers; but the more general rule is, that the male plants overrun the females. Some members of the Cincinnati Horticultural Society, especially appointed to investigate this subject, report that "few varieties have the flowers perfect in both sexual organs," etc. The most successful cultivators in Ohio plant for every seven rows of "pistillata," or female plants, one row of hermaphrodites, which afford pollen for both kinds; but the hermaphrodites, owing to their expenditure in the production of pollen, bear less fruit than the female plants.
The varieties differ in constitution. Some of our best English kinds, such as Keen's Seedlings, are too tender for certain parts of North America, where other English and many American varieties succeed perfectly. That splendid fruit, the British Queen, can be cultivated but in few places either in England or France: but this apparently depends more on the nature of the soil than on the climate; a famous gardener says that "no mortal could grow the British Queen at Shrubland Park unless the whole nature of the soil was altered." (10/117. Mr. D. Beaton in 'Cottage Gardener' 1860 page 86. See also 'Cottage Gardener' 1855 page 88 and many other authorities. For the Continent see F. Gloede in 'Gardener's Chronicle' 1862 page 1053.) La Constantine is one of the hardiest kinds, and can withstand Russian winters, but it is easily burnt by the sun, so that it will not succeed in certain soils either in England or the United States. (10/118. Rev. W.F. Radclyffe in 'Journal of Hort.' March 14, 1865 page 207.) The Filbert Pine Strawberry "requires more water than any other variety; and if the plants once suffer from drought, they will do little or no good afterwards." (10/119. Mr. H. Doubleday in 'Gardener's Chronicle' 1862 page 1101.) Cuthill's Black Prince Strawberry evinces a singular tendency to mildew; no less than six cases have been recorded of this variety suffering severely, whilst other varieties growing close by, and treated in exactly the same manner, were not at all infested by this fungus. (10/120. 'Gardener's Chronicle' 1854 page 254.) The time of maturity differs much in the different varieties: some belonging to the wood or alpine section produce a succession of crops throughout the summer.
GOOSEBERRY (Ribes grossularia).
No one, I believe, has hitherto doubted that all the cultivated kinds are sprung from the wild plant bearing this name, which is common in Central and Northern Europe; therefore it will be desirable briefly to specify all the points, though not very important, which have varied. If it be admitted that these differences are due to culture, authors perhaps will not be so ready to assume the existence of a large number of unknown wild parent- stocks for our other cultivated plants. The gooseberry is not alluded to by writers of the classical period. Turner mentions it in 1573, and Parkinson specifies eight varieties in 1629; the Catalogue of the Horticultural Society for 1842 gives 149 varieties, and the lists of the Lancashire nurserymen are said to include above 300 names. (10/121. Loudon's 'Encyclop. of Gardening' page 930; and Alph. De Candolle 'Geograph. Bot.' page 910.) In the 'Gooseberry Grower's Register' for 1862 I find that 243 distinct varieties have won prizes at various periods, so that a vast number must have been exhibited. No doubt the difference between many of the varieties is very small; but Mr. Thompson in classifying the fruit for the Horticultural Society found less confusion in the nomenclature of the gooseberry than of any other fruit, and he attributes this "to the great interest which the prize-growers have taken in detecting sorts with wrong names," and this shows that all the kinds, numerous as they are, can be recognised with certainty.
The bushes differ in their manner of growth, being erect, or spreading, or pendulous. The periods of leafing and flowering differ both absolutely and relatively to each other; thus the Whitesmith produces early flowers, which from not being protected by the foliage, as it is believed, continually fail to produce fruit. (10/122. Loudon's 'Gardener's Magazine' volume 4 1828 page 112.) The leaves vary in size, tint, and in depth of lobes; they are smooth, downy, or hairy on the upper surface. The branches are more or less downy or spinose; "the Hedgehog has probably derived its name from the singular bristly condition of its shoots and fruit." The branches of the wild gooseberry, I may remark, are smooth, with the exception of thorns at the bases of the buds. The thorns themselves are either very small, few and single, or very large and triple; they are sometimes reflexed and much dilated at their bases. In the different varieties the fruit varies in abundance, in the period of maturity, in hanging until shrivelled, and greatly in size, "some sorts having their fruit large during a very early period of growth, whilst others are small, until nearly ripe." The fruit varies also much in colour, being red, yellow, green, and white—the pulp of one dark-red gooseberry being tinged with yellow; in flavour; in being smooth or downy,—few, however, of the Red gooseberries, whilst many of the so-called Whites, are downy; or in being so spinose that one kind is called Henderson's Porcupine. Two kinds acquire when mature a powdery bloom on their fruit. The fruit varies in the thickness and veining of the skin, and, lastly, in shape, being spherical, oblong, oval, or obovate. (10/123. The fullest account of the gooseberry is given by Mr. Thompson in 'Transact. Hort. Soc.' volume 1 2nd series 1835 page 218 from which most of the foregoing facts are taken.)
I cultivated fifty-four varieties, and, considering how greatly the fruit differs, it was curious how closely similar the flowers were in all these kinds. In only a few I detected a trace of difference in the size or colour of the corolla. The calyx differed in a rather greater degree, for in some kinds it was much redder than in others; and in one smooth white gooseberry it was unusually red. The calyx also differed in the basal part being smooth or woolly, or covered with glandular hairs. It deserves notice, as being contrary to what might have been expected from the law of correlation, that a smooth red gooseberry had a remarkably hairy calyx. The flowers of the Sportsman are furnished with very large coloured bracteae; and this is the most singular deviation of structure which I have observed. These same flowers also varied much in the number of the petals, and occasionally in the number of the stamens and pistils; so that they were semi-monstrous in structure, yet they produced plenty of fruit. Mr. Thompson remarks that in the Pastime gooseberry "extra bracts are often attached to the sides of the fruit." (10/124. 'Catalogue of Fruits of Hort. Soc. Garden' 3rd edition 1842.)
The most interesting point in the history of the gooseberry is the steady increase in the size of the fruit. Manchester is the metropolis of the fanciers, and prizes from five shillings to five or ten pounds are yearly given for the heaviest fruit. The 'Gooseberry Growers Register' is published annually; the earliest known copy is dated 1786, but it is certain that meetings for the adjudication of prizes were held some years previously. (10/125. Mr. Clarkson of Manchester on the Culture of the Gooseberry in Loudon's 'Gardener's Magazine' volume 4 1828 page 482.) The 'Register' for 1845 gives an account of 171 Gooseberry Shows, held in different places during that year; and this fact shows on how large a scale the culture has been carried on. The fruit of the wild gooseberry is said (10/126. Downing 'Fruits of America' page 213.) to weigh about a quarter of an ounce or 5 dwts., that is, 120 grains; about the year 1786 gooseberries were exhibited weighing 10 dwts., so that the weight was then doubled; in 1817 26 dwts. 17 grs. was attained; there was no advance till 1825, when 31 dwts. 16 grs. was reached; in 1830 "Teazer" weighed 32 dwts. 13 grs.; in 1841 "Wonderful" weighed 32 dwts. 16 grs.; in 1844 "London" weighed 35 dwts. 12 grs., and in the following year 36 dwts. 16 grs.; and in 1852 in Staffordshire, the fruit of the same variety reached the astonishing weight of 37 dwts. 7 grs. (10/127. 'Gardener's Chronicle' 1844 page 811 where a table is given; and 1845 page 819. For the extreme weights gained see 'Journal of Horticulture' July 26, 1864 page 61.) or 896 grs.; that is, between seven or eight times the weight of the wild fruit. I find that a small apple, 6 1/2 inches in circumference, has exactly this same weight. The "London" gooseberry (which in 1852 had altogether gained 333 prizes) has, up to the present year of 1875, never reached a greater weight than that attained in 1852. Perhaps the fruit of the gooseberry has now reached the greatest possible weight, unless in the course of time some new and distinct variety shall arise.
This gradual, and on the whole steady increase of weight from the latter part of the last century to the year 1852, is probably in large part due to improved methods of cultivation, for extreme care is now taken; the branches and roots are trained, composts are made, the soil is mulched, and only a few berries are left on each bush (10/128. Mr. Saul of Lancaster in Loudon's 'Gardener's Mag.' volume 3 1828 page 421; and volume 10 1834 page 42.) but the increase no doubt is in main part due to the continued selection of seedlings which have been found to be more and more capable of yielding such extraordinary fruit. Assuredly the "Highwayman" in 1817 could not have produced fruit like that of the "Roaring Lion" in 1825; nor could the "Roaring Lion," though it was grown by many persons in many places, gain the supreme triumph achieved in 1852 by the "London" Gooseberry.
WALNUT (Juglans regia).
This tree and the common nut belong to a widely different order from the foregoing fruits, and are therefore here noticed. The walnut grows wild on the Caucasus and in the Himalaya, where Dr. Hooker (10/129. 'Himalayan Journals' 1854 volume 2 page 334. Moorcroft 'Travels' volume 2 page 146 describes four varieties cultivated in Kashmir.) found the fruit of full size, but "as hard as a hickory-nut." It has been found fossil, as M. de Saporta informs me, in the tertiary formation, of France.
In England the walnut presents considerable differences, in the shape and size of the fruit, in the thickness of the husk, and in the thinness of the shell; this latter quality has given rise to a variety called the thin- shelled, which is valuable, but suffers from the attacks of titmice. (10/130. 'Gardener's Chronicle' 1850 page 723.) The degree to which the kernel fills the shell varies much. In France there is a variety called the Grape or cluster-walnut, in which the nuts grow in "bunches of ten, fifteen, or even twenty together." There is another variety which bears on the same tree differently shaped leaves, like the heterophyllous hornbeam; this tree is also remarkable from having pendulous branches, and bearing elongated, large, thin-shelled nuts. (10/131. Paper translated in Loudon's 'Gardener's Mag.' 1829 volume 5 page 202.) M. Cardan has minutely described (10/132. Quoted in 'Gardener's Chronicle' 1849 page 101.) some singular physiological peculiarities in the June-leafing variety, which produces its leaves and flowers four or five weeks later than the common varieties; and although in August it is apparently in exactly the same state of forwardness as the other kinds, it retains its leaves and fruit much later in the autumn. These constitutional peculiarities are strictly inherited. Lastly, walnut-trees, which are properly monoicous, sometimes entirely fail to produce male flowers. (10/133. 'Gardener's Chronicle' 1847 pages 541 and 558.)
NUTS (Corylus avellana).
Most botanists rank all the varieties under the same species, the common wild nut. (10/134. The following details are taken from the 'Catalogue of Fruits, 1842 in Garden of Hort. Soc.' page 103; and from Loudon's 'Encyclop. of Gardening' page 943.) The husk, or involucre, differs greatly, being extremely short in Barr's Spanish, and extremely long in filberts, in which it is contracted so as to prevent the nut falling out. This kind of husk also protects the nut from birds, for titmice (Parus) have been observed (10/135. 'Gardener's Chron.' 1860 page 956.) to pass over filberts, and attack cobs and common nuts growing in the same orchard. In the purple-filbert the husk is purple, and in the frizzled-filbert it is curiously laciniated; in the red-filbert the pellicle of the kernel is red. The shell is thick in some varieties, but is thin in Cosford's-nut, and in one variety is of a bluish colour. The nut itself differs much in size and shape, being ovate and compressed in filberts, nearly round and of great size in cobs and Spanish nuts, oblong and longitudinally striated in Cosford's, and obtusely four-sided in the Downton Square nut.
CUCURBITACEOUS PLANTS.
These plants have been for a long period the opprobrium of botanists; numerous varieties have been ranked as species, and, what happens more rarely, forms which now must be considered as species have been classed as varieties. Owing to the admirable experimental researches of a distinguished botanist, M. Naudin (10/136. 'Annales des Sc. Nat. Bot.' 4th series volume 6 1856 page 5.), a flood of light has recently been thrown on this group of plants. M. Naudin, during many years, observed and experimented on above 1200 living specimens, collected from all quarters of the world. Six species are now recognised in the genus Cucurbita; but three alone have been cultivated and concern us, namely, C. maxima and pepo, which include all pumpkins, gourds, squashes, and the vegetable marrow, and C. moschata. These three species are not known in a wild state; but Asa Gray (10/137. 'American Journ. of Science' 2nd series volume 24 1857 page 442.) gives good reason for believing that some pumpkins are natives of N. America.
These three species are closely allied, and have the same general habit, but their innumerable varieties can always be distinguished, according to Naudin, by certain almost fixed characters; and what is still more important, when crossed they yield no seed, or only sterile seed; whilst the varieties spontaneously intercross with the utmost freedom. Naudin insists strongly (page 15), that, though these three species have varied greatly in many characters, yet it has been in so closely an analogous manner that the varieties can he arranged in almost parallel series, as we have seen with the forms of wheat, with the two main races of the peach, and in other cases. Though some of the varieties are inconstant in character, yet others, when grown separately under uniform conditions of life, are, as Naudin repeatedly (pages 6, 16, 35) urges, "douees d'une stabilite presque comparable a celle des especes les mieux caracterisees." One variety, l'Orangin (pages 43, 63), has such prepotency in transmitting its character, that when crossed with other varieties a vast majority of the seedlings come true. Naudin, referring (page 47) to C. pepo, says that its races "ne different des especes veritables qu'en ce qu'elles peuvent s'allier les unes aux autres par voie d'hybridite, sans que leur descendance perde la faculte de se perpetuer." If we were to trust to external differences alone, and give up the test of sterility, a multitude of species would have to be formed out of the varieties of these three species of Cucurbita. Many naturalists at the present day lay far too little stress, in my opinion, on the test of sterility; yet it is not improbable that distinct species of plants after a long course of cultivation and variation may have their mutual sterility eliminated, as we have every reason to believe has occurred with domesticated animals. Nor, in the case of plants under cultivation, should we be justified in assuming that varieties never acquire a slight degree of mutual sterility, as we shall more fully see in a future chapter when certain facts are given on the high authority of Gartner and Kolreuter. (10/138. Gartner 'Bastarderzeugung' 1849 s. 87 and s. 169 with respect to Maize; on Verbascum ibid s. 92 and 181; also his 'Kenntniss der Befruchtung' s. 137. With respect to Nicotiana see Kolreuter 'Zweite Forts.' 1764 s. 53; though this is a somewhat different case.)
The forms of C. pepo are classed by Naudin under seven sections, each including subordinate varieties. He considers this plant as probably the most variable in the world. The fruit of one variety (pages 33, 46) exceeds in value that of another by more than two thousand fold! When the fruit is of very large size, the number produced is few (page 45); when of small size, many are produced. No less astonishing (page 33) is the variation in the shape of the fruit, the typical form apparently is egg-like, but this becomes either drawn out into a cylinder, or shortened into a flat disc. We have also an almost infinite diversity in the colour and state of surface of the fruit, in the hardness both of the shell and of the flesh, and in the taste of the flesh, which is either extremely sweet, farinaceous, or slightly bitter. The seeds also differ in a slight degree in shape, and wonderfully in size (page 34), namely, from six or seven to more than twenty-five millimetres in length.
In the varieties which grow upright or do not run and climb, the tendrils, though useless (page 31), are either present or are represented by various semi-monstrous organs, or are quite absent. The tendrils are even absent in some running varieties in which the stems are much elongated. It is a singular fact that (page 31) in all the varieties with dwarfed stems, the leaves closely resemble each other in shape.]
Those naturalists who believe in the immutability of species often maintain that, even in the most variable forms, the characters which they consider of specific value are unchangeable. To give an example from a conscientious writer (10/139. Godron 'De l'Espece' tome 2 page 64.) who, relying on the labours of M. Naudin, and referring to the species of Cucurbita, says, "au milieu de toutes les variations du fruit, les tiges, les feuilles, les calices, les corolles, les etamines restent invariables dans chacune d'elles." Yet M. Naudin, in describing Cucurbita pepo (page 30), says, "Ici, d'ailleurs, ce ne sont pas seulement les fruits qui varient, c'est aussi le feuillage et tout le port de la plante. Neanmoins, je crois qu'on la distinguera toujours facilement des deux autres especes, si l'on veut ne pas perdre de vue les caracteres differentiels que je m'efforce de faire ressortir. Ces caracteres sont quelquefois peu marques: il arrive meme que plusieurs d'entre eux s'effacent presque entierement, mais ii en reste toujours quelques-uns qui remettent l'observateur sur la voie." Now let it be noted what a difference, with regard to the immutability of the so- called specific characters this paragraph produces on the mind, from that above quoted from M. Godron.
I will add another remark: naturalists continually assert that no important organ varies; but in saying this they unconsciously argue in a vicious circle; for if an organ, let it be what it may, is highly variable, it is regarded as unimportant, and under a systematic point of view this is quite correct. But as long as constancy is thus taken as the criterion of importance, it will indeed be long before an important organ can be shown to be inconstant. The enlarged form of the stigmas, and their sessile position on the summit of the ovary, must be considered as important characters, and were used by Gasparini to separate certain pumpkins as a DISTINCT GENUS; but Naudin says (page 20), these parts have no constancy, and in the flowers of the Turban varieties of C. maxima they sometimes resume their ordinary structure. Again, in C. maxima, the carpels (page 19) which form the turban project even as much as two-thirds of their length out of the receptacle, and this latter part is thus reduced to a sort of platform; but this remarkable structure occurs only in certain varieties, and graduates into the common form in which the carpels are almost entirely enveloped within the receptacle. In C. moschata the ovarium (page 50) varies greatly in shape, being oval, nearly spherical, or cylindrical, more or less swollen in the upper part, or constricted round the middle, and either straight or curved. When the ovarium is short and oval the interior structure does not differ from that of C. maxima and pepo, but when it is elongated the carpels occupy only the terminal and swollen portion. I may add that in one variety of the cucumber (Cucumis sativus) the fruit regularly contains five carpels instead of three. (10/140. Naudin 'Annal. des Sc. Nat.' 4th series Bot. tome 11 1859 page 28.) I presume that it will not be disputed that we here have instances of great variability in organs of the highest physiological importance, and with most plants of the highest classificatory importance.
[Sageret (10/141. 'Memoire sur les Cucurbitacees' 1826 pages 6, 24.) and Naudin found that the cucumber (C. sativus) could not be crossed with any other species of the genus; therefore no doubt it is specifically distinct from the melon. This will appear to most persons a superfluous statement; yet we hear from Naudin (10/142. 'Flore des Serres' October 1861 quoted in 'Gardener's Chronicle' 1861 page 1135. I have often consulted and taken some facts from M. Naudin's Memoir on Cucumis in 'Annal. des Sc. Nat.' 4th series Bot. tome 11 1859 page 5.) that there is a race of melons, in which the fruit is so like that of the cucumber, "both externally and internally, that it is hardly possible to distinguish the one from the other except by the leaves." The varieties of the melon seem to be endless, for Naudin after six years' study had not come to the end of them: he divides them into ten sections, including numerous sub-varieties which all intercross with perfect ease. (10/143. See also Sageret 'Memoire' page 7.) Of the forms considered by Naudin to be varieties, botanists have made thirty distinct species! "and they had not the slightest acquaintance with the multitude of new forms which have appeared since their time." Nor is the creation of so many species at all surprising when we consider how strictly their characters are transmitted by seed, and how wonderfully they differ in appearance: "Mira est quidem foliorum et habitus diversitas, sed multo magis fructuum," says Naudin. The fruit is the valuable part, and this, in accordance with the common rule, is the most modified part. Some melons are only as large as small plums, others weigh as much as sixty-six pounds. One variety has a scarlet fruit! Another is not more than an inch in diameter, but sometimes more than a yard in length, "twisting about in all directions like a serpent." It is a singular fact that in this latter variety many parts of the plant, namely, the stems, the footstalks of the female flowers, the middle lobe of the leaves, and especially the ovarium, as well as the mature fruit, all show a strong tendency to become elongated. Several varieties of the melon are interesting from assuming the characteristic features of distinct species and even of distinct though allied genera: thus the serpent-melon has some resemblance to the fruit of Trichosanthes anguina; we have seen that other varieties closely resemble cucumbers; some Egyptian varieties have their seeds attached to a portion of the pulp, and this is characteristic of certain wild forms. Lastly, a variety of melon from Algiers is remarkable from announcing its maturity by "a spontaneous and almost sudden dislocation," when deep cracks suddenly appear, and the fruit falls to pieces; and this occurs with the wild C. momordica. Finally, M. Naudin well remarks that this "extraordinary production of races and varieties by a single species and their permanence when not interfered with by crossing, are phenomena well calculated to cause reflection."
USEFUL AND ORNAMENTAL TREES.
Trees deserve a passing notice on account of the numerous varieties which they present, differing in their precocity, in their manner of growth, their foliage, and bark. Thus of the common ash (Fraxinus excelsior) the catalogue of Messrs. Lawson of Edinburgh includes twenty-one varieties, some of which differ much in their bark; there is a yellow, a streaked reddish-white, a purple, a wart-barked and a fungous-barked variety. (10/144. Loudon's 'Arboretum et Fruticetum' volume 2 page 1217.) Of hollies no less than eighty-four varieties are grown alongside each other in Mr. Paul's nursery. (10/145. 'Gardener's Chronicle' 1866 page 1096.) In the case of trees, all the recorded varieties, as far as I can find out, have been suddenly produced by one single act of variation. The length of time required to raise many generations, and the little value set on the fanciful varieties, explains how it is that successive modifications have not been accumulated by selection; hence, also, it follows that we do not here meet with sub-varieties subordinate to varieties, and these again subordinate to higher groups. On the Continent, however, where the forests are more carefully attended to than in England, Alph. De Candolle (10/146. 'Geograph. Bot.' page 1096.) says that there is not a forester who does not search for seeds from that variety which he esteems the most valuable.
Our useful trees have seldom been exposed to any great change of conditions; they have not been richly manured, and the English kinds grow under their proper climate. Yet in examining extensive beds of seedlings in nursery-gardens considerable differences may be generally observed in them; and whilst touring in England I have been surprised at the amount of difference in the appearance of the same species in our hedgerows and woods. But as plants vary so much in a truly wild state, it would be difficult for even a skilful botanist to pronounce whether, as I believe to be the case, hedgerow trees vary more than those growing in a primeval forest. Trees when planted by man in woods or hedges do not grow where they would naturally be able to hold their place against a host of competitors, and are therefore exposed to conditions not strictly natural: even this slight change would probably suffice to cause seedlings raised from such trees to be variable. Whether or not our half-wild English trees, as a general rule, are more variable than trees growing in their native forests, there can hardly be a doubt that they have yielded a greater number of strongly-marked and singular variations of structure.
In manner of growth, we have weeping or pendulous varieties of the willow, ash, elm, oak, and yew, and other trees; and this weeping habit is sometimes inherited, though in a singularly capricious manner. In the Lombardy poplar, and in certain fastigiate or pyramidal varieties of thorns, junipers, oaks, etc., we have an opposite kind of growth. The Hessian oak (10/147. 'Gardener's Chronicle' 1842 page 36.), which is famous from its fastigiate habit and size, bears hardly any resemblance in general appearance to a common oak; "its acorns are not sure to produce plants of the same habit; some, however, turn out the same as the parent-tree." Another fastigiate oak is said to have been found wild in the Pyrenees, and this is a surprising circumstance; it generally comes so true by seed, that De Candolle considered it as specifically distinct. (10/148. Loudon's 'Arboretum et Fruticetum' volume 3 page 1731.) The fastigiate Juniper (J. suecica) likewise transmits its character by seed. (10/149. Ibid volume 4 page 2489.) Dr. Falconer informs me that in the Botanic Gardens at Calcutta the great heat caused apple-trees to become fastigiate; and we thus see the same result following from the effects of climate and from some unknown cause. (10/150. Godron 'De l'Espece' tome 2 page 91 describes four varieties of Robinia remarkable from their manner of growth.)
In foliage we have variegated leaves which are often inherited; dark purple or red leaves, as in the hazel, barberry, and beech, the colour in these two latter trees being sometimes strongly and sometimes weakly inherited (10/151. 'Journal of a Horticultural Tour, by Caledonian Hort. Soc.' 1823 page 107. Alph. De Candolle 'Geograph. Bot.' page 1083. Verlot 'Sur La Production des Varietes' 1865 page 55 for the Barberry.); deeply-cut leaves; and leaves covered with prickles, as in the variety of the holly well called ferox, which is said to reproduce itself by seed. (10/152. Loudon's 'Arboretum et Fruticetum' volume 2 page 508.) In fact, nearly all the peculiar varieties evince a tendency, more or less strongly marked, to reproduce themselves by seed. (10/153. Verlot 'Des Varietes' 1865 page 92.) This is to a certain extent the case, according to Bosc (10/154. Loudon's 'Arboretum et Fruticetum' volume 3 page 1376.), with three varieties of the elm, namely, the broad-leafed, lime-leafed, and twisted elm, in which latter the fibres of the wood are twisted. Even with the heterophyllous hornbeam (Carpinus betulus), which bears on each twig leaves of two shapes, "several plants raised from seed all retained "the same peculiarity." (10/155. 'Gardener's Chronicle' 1841 page 687.) I will add only one other remarkable case of variation in foliage, namely, the occurrence of two sub- varieties of the ash with simple instead of pinnated leaves, and which generally transmit their character by seed. (10/156. Godron 'De l'Espece' tome 2 page 89. In Loudon's 'Gardener's Mag.' volume 12 1836 page 371, a variegated bushy ash is described and figured, as having simple leaves; it originated in Ireland.) The occurrence, in trees belonging to widely different orders, of weeping and fastigiate varieties, and of trees bearing deeply cut, variegated, and purple leaves, shows that these deviations of structure must result from some very general physiological laws.
Differences in general appearance and foliage, not more strongly marked than those above indicated, have led good observers to rank as distinct species certain forms which are now known to be mere varieties. Thus, a plane-tree long cultivated in England was considered by almost every one as a North American species: but is now ascertained by old records, as I am informed by Dr. Hooker, to be a variety. So, again, the Thuja pendula or filiformis was ranked by such good observers as Lambert, Wallich, and others, as a true species; but it is now known that the original plants, five in number, suddenly appeared in a bed of seedlings, raised at Mr. Loddige's nursery, from T. orientalis; and Dr. Hooker has adduced excellent evidence that at Turin seeds of T. pendula have reproduced the parent form, T. orientalis. (10/157. 'Gardener's Chronicle' 1863 page 575.)
Every one must have noticed how certain individual trees regularly put forth and shed their leaves earlier or later than others of the same species. There is a famous horse-chestnut in the Tuileries which is named from leafing so much earlier than the others. There is also an oak near Edinburgh which retains its leaves to a very late period. These differences have been attributed by some authors to the nature of the soil in which the trees grow; but Archbishop Whately grafted an early thorn on a late one, and vice versa, and both grafts kept to their proper periods, which differed by about a fortnight, as if they still grew on their own stocks. (10/158. Quoted from Royal Irish Academy in 'Gardener's Chronicle' 1841 page 767.) There is a Cornish variety of the elm which is almost an evergreen, and is so tender that the shoots are often killed by the frost; and the varieties of the Turkish oak (Q. cerris) may be arranged as deciduous, sub-evergreen, and evergreen. (10/159. Loudon 'Arboretum et Fruticetum:' for Elm see volume 3 page 1376; for Oak page 1846.)
SCOTCH FIR (Pinus sylvestris).
I allude to this tree as it bears on the question of the greater variability of our hedgerow trees compared with those under strictly natural conditions. A well-informed writer (10/160. 'Gardener's Chronicle' 1849?, page 822.) states that the Scotch fir presents few varieties in its native Scotch forests; but that it "varies much in figure and foliage, and in the size, shape, and colour of its cones, when several generations have been produced away from its native locality." There is little doubt that the highland and lowland varieties differ in the value of their timber, and that they can be propagated truly by seed; thus justifying Loudon's remark, that "a variety is often of as much importance as a species, and sometimes far more so." (10/161. 'Arboretum et Fruticetum' volume 4 page 2150.) I may mention one rather important point in which this tree occasionally varies; in the classification of the Coniferae, sections are founded on whether two, three, or five leaves are included in the same sheath; the Scotch fir has properly only two leaves thus enclosed, but specimens have been observed with groups of three leaves in a sheath. (10/162. 'Gardener's Chronicle' 1852 page 693.) Besides these differences in the semi-cultivated Scotch fir, there are in several parts of Europe natural or geographical races, which have been ranked by some authors as distinct species. (10/163. See 'Beitrage zur Kenntniss Europaischer Pinus-arten von Dr. Christ: Flora, 1864.' He shows that in the Ober-Engadin P. sylvestris and montana are connected by intermediate links.) Loudon (10/164. 'Arboretum et Fruticetum' volume 4 pages 2159 and 2189.) considers P. pumilio, with its several sub- varieties, as mughus, nana, etc., which differ much when planted in different soils, and only come "tolerably true from seed," as alpine varieties of the Scotch fir; if this were proved to be the case, it would be an interesting fact as showing that dwarfing from long exposure to a severe climate is to a certain extent inherited.
THE HAWTHORN (Crataegus oxyacantha).
The Hawthorn has varied much. Besides endless slighter variations in the form of the leaves, and in the size, hardness, fleshiness, and shape of the berries, Loudon (10/165. Ibid volume 2 page 830; Loudon's 'Gardener's Mag.' volume 6 1830 page 714.) enumerates twenty-nine well-marked varieties. Besides those cultivated for their pretty flowers, there are others with golden-yellow, black, and whitish berries; others with woolly berries, and others with re-curved thorns. Loudon truly remarks that the chief reason why the hawthorn has yielded more varieties than most other trees, is that nurserymen select any remarkable variety out of the immense beds of seedlings which are annually raised for making hedges. The flowers of the hawthorn usually include from one to three pistils; but in two varieties, named monogyna and sibirica, there is only a single pistil; and d'Asso states that the common thorn in Spain is constantly in this state. (10/166. Loudon's 'Arboretum et Fruticetum' volume 2 page 834.) There is also a variety which is apetalous, or has its petals reduced to mere rudiments. The famous Glastonbury thorn flowers and leafs towards the end of December, at which time it bears berries produced from an earlier crop of flowers. (10/167. Loudon's 'Gardener's Mag.' volume 9 1833 page 123.) It is worth notice that several varieties of the hawthorn, as well as of the lime and juniper, are very distinct in their foliage and habit whilst young, but in the course of thirty or forty years become extremely like each other (10/168. Ibid volume 11 1835 page 503.) thus reminding us of the well-known fact that the deodar, the cedar of Lebanon, and that of the Atlas, are distinguished with the greatest ease whilst young, but with difficulty when old.
FLOWERS.
I shall not for several reasons treat the variability of plants which are cultivated for their flowers alone at any great length. Many of our favourite kinds in their present state are the descendants of two or more species crossed and commingled together, and this circumstance alone would render it difficult to detect the difference due to variation. For instance, our Roses, Petunias, Calceolarias, Fuchsias, Verbenas, Gladioli, Pelargoniums, etc., certainly have had a multiple origin. A botanist well acquainted with the parent-forms would probably detect some curious structural differences in their crossed and cultivated descendant; and he would certainly observe many new and remarkable constitutional peculiarities. I will give a few instances, all relating to the Pelargonium, and taken chiefly from Mr. Beck (10/169. 'Gardener's Chronicle' 1845 page 623.) a famous cultivator of this plant: some varieties require more water than others; some are "very impatient of the knife if too greedily used in making cuttings;" some, when potted, scarcely "show a root at the outside of the ball of the earth;" one variety requires a certain amount of confinement in the pot to make it throw up a flower- stem; some varieties bloom well at the commencement of the season, others at the close; one variety is known (10/170. D. Beaton in 'Cottage Gardener' 1860 page 377. See also Mr. Beck on the habits of Queen Mab in 'Gardener's Chronicle' 1845 page 226.), which will stand "even pine-apple top and bottom heat, without looking any more drawn than if it had stood in a common greenhouse; and Blanche Fleur seems as if made on purpose for growing in winter, like many bulbs, and to rest all summer." These odd constitutional peculiarities would enable a plant in a state of nature to become adapted to widely different circumstances and climates.
Flowers possess little interest under our present point of view, because they have been almost exclusively attended to and selected for their beautiful colour, size, perfect outline, and manner of growth. In these particulars hardly one long-cultivated flower can be named which has not varied greatly. What does a florist care for the shape and structure of the organs of fructification, unless, indeed, they add to the beauty of the flower? When this is the case, flowers become modified in important points; stamens and pistils may be converted into petals, and additional petals may be developed, as in all double flowers. The process of gradual selection by which flowers have been rendered more and more double, each step in the process of conversion being inherited, has been recorded in several instances. In the so-called double flowers of the Compositae, the corollas of the central florets are greatly modified, and the modifications are likewise inherited. In the columbine (Aquilegia vulgaris) some of the stamens are converted into petals having the shape of nectaries, one neatly fitting into the other; but in one variety they are converted into simple petals. (10/171. Moquin-Tandon 'Elements de Teratologie' 1841 page 213.) In the "hose in hose" primulae, the calyx becomes brightly coloured and enlarged so as to resemble a corolla; and Mr. W. Wooler informs me that this peculiarity is transmitted; for he crossed a common polyanthus with one having a coloured calyx (10/172. See also 'Cottage Gardener' 1860 page 133.) and some of the seedlings inherited the coloured calyx during at least six generations. In the "hen-and-chicken" daisy the main flower is surrounded by a brood of small flowers developed from buds in the axils of the scales of the involucre. A wonderful poppy has been described, in which the stamens are converted into pistils; and so strictly was this peculiarity inherited that, out of 154 seedlings, one alone reverted to the ordinary and common type. (10/173. Quoted by Alph. de Candolle 'Bibl. Univ.' November 1862 page 58.) Of the cock's-comb (Celosia cristata), which is an annual, there are several races in which the flower-stem is wonderfully "fasciated" or compressed; and one has been exhibited (10/174. Knight 'Transact. Hort. Soc.' volume 4 page 322.) actually eighteen inches in breadth. Peloric races of Gloxinia speciosa and Antirrhinum majus can be propagated by seed, and they differ in a wonderful manner from the typical form both in structure and appearance.
A much more remarkable modification has been recorded by Sir William and Dr. Hooker (10/175. 'Botanical Magazine' tab. 5160 figure 4; Dr. Hooker in 'Gardener's Chronicle' 1860 page 190; Prof. Harvey in 'Gardener's Chronicle' 1860 page 145; Mr. Crocker in 'Gardener's Chron.' 1861 page 1092.) in Begonia frigida. This plant properly produces male and female flowers on the same fascicles; and in the female flowers the perianth is superior; but a plant at Kew produced, besides the ordinary flowers, others which graduated towards a perfect hermaphrodite structure; and in these flowers the perianth was inferior. To show the importance of this modification under a classificatory point of view, I may quote what Prof. Harvey says, namely, that had it "occurred in a state of nature, and had a botanist collected a plant with such flowers, he would not only have placed it in a distinct genus from Begonia, but would probably have considered it as the type of a new natural order." This modification cannot in one sense be considered as a monstrosity, for analogous structures naturally occur in other orders, as with Saxifragae and Aristolochiaceae. The interest of the case is largely added to by Mr. C.W. Crocker's observation that seedlings from the NORMAL flowers produced plants which bore, in about the same proportion as the parent-plant, hermaphrodite flowers having inferior perianths. The hermaphrodite flowers fertilised with their own pollen were sterile.
If florists had attended to, selected, and propagated by seed other modifications of structure besides those which are beautiful, a host of curious varieties would certainly have been raised; and they would probably have transmitted their characters so truly that the cultivator would have felt aggrieved, as in the case of culinary vegetables, if his whole bed had not presented a uniform appearance. Florists have attended in some instances to the leaves of their plant, and have thus produced the most elegant and symmetrical patterns of white, red, and green, which, as in the case of the pelargonium, are sometimes strictly inherited. (10/176. Alph. de Candolle 'Geograph. Bot.' page 1083; 'Gardener's Chronicle' 1861 page 433. The inheritance of the white and golden zones in Pelargonium largely depends on the nature of the soil. See D. Beaton in 'Journal of Horticulture' 1861 page 64.) Any one who will habitually examine highly- cultivated flowers in gardens and greenhouses will observe numerous deviations in structure; but most of these must be ranked as mere monstrosities, and are only so far interesting as showing how plastic the organisation becomes under high cultivation. From this point of view such works as Professor Moquin-Tandon's 'Teratologie' are highly instructive.
ROSES.
These flowers offer an instance of a number of forms generally ranked as species, namely, R. centifolia, gallica, alba, damascena, spinosissima, bracteata, indica, semperflorens, moschata, etc., which have largely varied and been intercrossed. The genus Rosa is a notoriously difficult one, and, though some of the above forms are admitted by all botanists to be distinct species, others are doubtful; thus, with respect to the British forms, Babington makes seventeen, and Bentham only five species. The hybrids from some of the most distinct forms—for instance, from R. indica, fertilised by the pollen of R. centifolia—produce an abundance of seed; I state this on the authority of Mr. Rivers (10/177. 'Rose Amateur's Guide' T. Rivers 1837 page 21.) from whose work I have drawn most of the following statements. As almost all the aboriginal forms brought from different countries have been crossed and re-crossed, it is no wonder that Targioni- Tozzetti, in speaking of the common roses of the Italian gardens, remarks that "the native country and precise form of the wild type of most of them are involved in much uncertainty." (10/178. 'Journal Hort. Soc.' volume 9 1855 page 182.) Nevertheless, Mr. Rivers in referring to R. indica (page 68) says that the descendants of each group may generally be recognised by a close observer. The same author often speaks of roses as having been a little hybridised; but it is evident that in very many cases the differences due to variation and to hybridisation can now only be conjecturally distinguished.
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 constitutional 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 anticipates (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 assuredly it has already achieved wonders.
It may be worth while briefly to give the well-known history of one class 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, classed 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 circumstances 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 passes 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 constitutional 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 illustrate 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 asserts (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, Capsicum, Millets, Sorghum, etc., have been passed 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 passed 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 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.