The pods and seeds, which with natural species afford such constant characters, differ greatly in the cultivated varieties of the pea; and these are the valuable, and consequently the selected parts. SUGAR PEAS, or POIS SANS PARCHEMIN, are remarkable from their thin pods, which, whilst young, are cooked and eaten whole; and in this group, which, according to Mr. Gordon includes eleven sub-varieties, it is the pod which differs most; thus LEWIS"S NEGRO-PODDED PEA has a straight, broad, smooth, and dark- purple pod, with the husk not so thin as in the other kinds; the pod of another variety is extremely bowed; that of the POIS GEANT is much pointed at the extremity; and in the variety "A GRANDS COSSES" the peas are seen through the husk in so conspicuous a manner that the pod, especially when dry, can hardly at first be recognised as that of a pea.
In the ordinary varieties the pods also differ much in size;--in colour, that of WOODFORD"S GREEN MARROW being bright-green when dry, instead of pale brown, and that of the purple-podded pea being expressed by its name;- -in smoothness, that of DANECROFT being remarkably glossy, whereas that of the NE PLUS ULTRA is rugged; in being either nearly cylindrical, or broad and flat;--in being pointed at the end, as in THURSTON"S RELIANCE, or much truncated, as in the AMERICAN DWARF. In the AUVERGNE PEA the whole end of the pod is bowed upwards. In the QUEEN OF THE DWARFS and in SCIMITAR PEAS the pod is almost elliptic in shape. I here give drawings of the four most distinct pods produced by the plants cultivated by me.
(FIGURE 41. PODS AND PEAS. I. Queen of Dwarfs. II. American Dwarf. III.
Thurston"s Reliance. IV. Pois Geant sans parchemin. a. Dan O"Rourke Pea. b.
Queen of Dwarfs Pea. c. Knight"s Tall White Marrow. a. Lewis"s Negro Pea.)
In the pea itself we have every tint between almost pure white, brown, yellow, and intense green; in the varieties of the SUGAR PEAS we have these same tints, together with red pa.s.sing through fine purple into a dark chocolate tint. These colours are either uniform or distributed in dots, striae, or moss-like marks; they depend in some cases on the colour of the cotyledons seen through the skin, and in other cases on the outer coats of the pea itself. In the different varieties, the pods contain, according to Mr. Gordon, from eleven or twelve to only four or five peas. The largest peas are nearly twice as much in diameter as the smallest; and the latter are not always borne by the most dwarfed kinds. Peas differ much in shape, being smooth and spherical, smooth and oblong, nearly oval in the QUEEN OF THE DWARFS, and nearly cubical and crumpled in many of the larger kinds.
With respect to the value of the differences between the chief varieties, it cannot be doubted that, if one of the tall SUGAR-PEAS, with purple flowers, thin-skinned pods of an extraordinary shape, including large, dark-purple peas, grew wild by the side of the lowly QUEEN OF THE DWARFS, with white flowers, greyish-green, rounded leaves, scimitar-like pods, containing oblong, smooth, pale-coloured peas, which became mature at a different season: or by the side of one of the gigantic sorts, like the CHAMPION OF ENGLAND, with leaves of great size, pointed pods, and large, green, crumpled, almost cubical peas,--all three kinds would be ranked as distinct species.
Andrew Knight (9/85. "Phil. Tract." 1799 page 196.) has observed that the varieties of peas keep very true, because they are not crossed by insects.
As far as the fact of keeping true is concerned, I hear from Mr. Masters of Canterbury, well known as the originator of several new kinds, that certain varieties have remained constant for a considerable time,--for instance, KNIGHT"S BLUE DWARF, which came out about the year 1820. (9/86. "Gardener"s Magazine" volume 1 1826 page 153.) But the greater number of varieties have a singularly short existence: thus Loudon remarks (9/87. "Encyclopaedia of Gardening" page 823.) that "sorts which were highly approved in 1821, are now, in 1833, nowhere to be found;" and on comparing the lists of 1833 with those of 1855, I find that nearly all the varieties have changed. Mr.
Masters informs me that the nature of the soil causes some varieties to lose their character. As with other plants, certain varieties can be propagated truly, whilst others show a determined tendency to vary; thus two peas differing in shape, one round and the other wrinkled, were found by Mr. Masters within the same pod, but the plants raised from the wrinkled kind always evinced a strong tendency to produce round peas. Mr. Masters also raised from a plant of another variety four distinct sub-varieties, which bore blue and round, white and round, blue and wrinkled, and white and wrinkled peas; and although he sowed these four varieties separately during several successive years, each kind always reproduced all four kinds mixed together!
With respect to the varieties not naturally intercrossing, I have ascertained that the pea, which in this respect differs from some other Leguminosae, is perfectly fertile without the aid of insects. Yet I have seen humble-bees whilst sucking the nectar depress the keel-petals, and become so thickly dusted with pollen, that it could hardly fail to be left on the stigma of the next flower which was visited. Nevertheless, distinct varieties growing closely together rarely cross; and I have reason to believe that this is due to their stigmas being prematurely fertilised in this country by pollen from the same flower. The horticulturists who raise seed-peas are thus enabled to plant distinct varieties close together without any bad consequences; and it is certain, as I have myself found, that true seed may be saved during at least several generations under these circ.u.mstances. (9/88. See Dr. Anderson to the same effect in the "Bath Soc.
Agricultural Papers" volume 4 page 87.) Mr. Fitch raised, as he informs me, one variety for twenty years, and it always came true, though grown close to other varieties. From the a.n.a.logy of kidney-beans I should have expected (9/89. I have published full details of experiments on this subject in the "Gardener"s Chronicle" 1857 October 25.) that varieties thus circ.u.mstanced would have occasionally crossed; and I shall give in the eleventh chapter two cases of this having occurred, as shown (in a manner hereafter to be explained) by the pollen of the one variety having acted directly on the seeds of the other. Whether many of the new varieties which incessantly appear are due to such occasional and accidental crosses, I do not know.
Nor do I know whether the short existence of almost all the numerous varieties is the result of mere change of fashion, or of their having a weak const.i.tution, from being the product of long-continued self- fertilisation. It may, however, be noticed that several of Andrew Knight"s varieties, which have endured longer than most kinds, were raised towards the close of the last century by artificial crosses; some of them, I believe, were still vigorous in 1860; but now, in 1865, a writer, speaking (9/90. "Gardener"s Chronicle" 1865 page 387.) of Knight"s four kinds of marrows, says, they have acquired a famous history, but their glory has departed.
With respect to Beans (Faba vulgaris), I will say but little. Dr. Alefield has given (9/91. "Bonplandia" 10, 1862 s. 348.) short diagnostic characters of forty varieties. Everyone who has seen a collection must have been struck with the great difference in shape, thickness, proportional length and breadth, colour, and size which beans present. What a contrast between a Windsor and Horse-bean! As in the case of the pea, our existing varieties were preceded during the Bronze age in Switzerland (9/92. Heer "Die Pflanzen der Pfahlbauten" 1866 s. 22.) by a peculiar and now extinct variety producing very small beans. (9/93. Mr. Bentham informs me that in Poitou and the adjoining parts of France, varieties of Phaseolus vulgaris are extremely numerous, and so different that they were described by Savi as distinct species. Mr. Bentham believes that all are descended from an unknown eastern species. Although the varieties differ so greatly in stature and in their seeds, "there is a remarkable sameness in the neglected characters of foliage and flowers, and especially in the bracteoles, an insignificant character in the eyes even of botanists.")
POTATO (Solanum tuberosum).
There is little doubt about the parentage of this plant; for the cultivated varieties differ extremely little in general appearance from the wild species, which can be recognised in its native land at the first glance.
(9/94. Darwin "Journal of Researches" 1845 page 285. Sabine in "Transact.
Hort. Soc." volume 5 page 249.) The varieties cultivated in Britain are numerous; thus Lawson (9/95. "Synopsis of the Vegetable Products of Scotland" quoted in Wilson"s "British Farming" page 317.) gives a description of 175 kinds. I planted eighteen kinds in adjoining rows; their stems and leaves differed but little, and in several cases there was as great a difference between the individuals of the same variety as between the different varieties. The flower varied in size, and in colour between white and purple, but in no other respect, except that in one kind the sepals were somewhat elongated. One strange variety has been described which always produces two sorts of flowers, the first double and sterile, the second single and fertile. (9/96. Sir G. Mackenzie, in "Gardener"s Chronicle" 1845 page 790.) The fruit or berries also differ, but only in a slight degree. (9/97. Putsche und Vertuch "Versuch einer Monographie der Kartoffeln" 1819 s. 9, 15. See also Dr. Anderson "Recreations in Agriculture" volume 4 page 325.) The varieties are liable in very different degree to the attack of the Colorado potato-beetle. (9/98. Walsh "The American Entomologist" 1869 page 160. Also S. Tenney "The American Naturalist" May 1871 page 171.)
The tubers, on the other hand, present a wonderful amount of diversity.
This fact accords with the principle that the valuable and selected parts of all cultivated productions present the greatest amount of modification.
They differ much in size and shape, being globular, oval, flattened, kidney-like, or cylindrical. One variety from Peru is described (9/99.
"Gardener"s Chronicle" 1862 page 1052.) as being quite straight, and at least six inches in length, though no thicker than a man"s finger. The eyes or buds differ in form, position, and colour. The manner in which the tubers are arranged on the so-called roots or rhizomes is different; thus, in the gurken-kartoffeln they form a pyramid with the apex downwards, and in another variety they bury themselves deep in the ground. The roots themselves run either near the surface or deep in the ground. The tubers also differ in smoothness and colour, being externally white, red, purple, or almost black, and internally white, yellow, or almost black. They differ in flavour and quality, being either waxy or mealy; in their period of maturity, and in their capacity for long preservation.
As with many other plants which have been long propagated by bulbs, tubers, cuttings, etc., by which means the same individual is exposed during a length of time to diversified conditions, seedling potatoes generally display innumerable slight differences. Several varieties, even when propagated by tubers, are far from constant, as will be seen in the chapter on Bud-variation. Dr. Anderson (9/100. "Bath Society Agricult. Papers"
volume 5 page 127. And "Recreations in Agriculture" volume 5 page 86.) procured seed from an Irish purple potato, which grew far from any other kind, so that it could not at least in this generation have been crossed, yet the many seedlings varied in almost every possible respect, so that "scarcely two plants were exactly alike." Some of the plants which closely resembled each other above ground, produced extremely dissimilar tubers; and some tubers which externally could hardly be distinguished, differed widely in quality when cooked. Even in this case of extreme variability, the parent-stock had some influence on the progeny, for the greater number of the seedlings resembled in some degree the parent Irish potato. Kidney potatoes must be ranked amongst the most highly cultivated and artificial races; nevertheless their peculiarities can often be strictly propagated by seed. A great authority, Mr. Rivers (9/101. "Gardener"s Chronicle" 1863 page 643.) states that "seedlings from the ash-leaved kidney always bear a strong resemblance to their parent. Seedlings from the fluke-kidney are still more remarkable for their adherence to their parent stock, for, on closely observing a great number during two seasons, I have not been able to observe the least difference, either in earliness, productiveness, or in the size or shape of their tubers."
CHAPTER 1.X.
PLANTS continued--FRUITS--ORNAMENTAL TREES--FLOWERS.
FRUITS.
GRAPES.
VARY IN ODD AND TRIFLING PARTICULARS.
MULBERRY.
THE ORANGE GROUP.
SINGULAR RESULTS FROM CROSSING.
PEACH AND NECTARINE.
BUD-VARIATION.
a.n.a.lOGOUS VARIATION.
RELATION TO THE ALMOND.
APRICOT.
PLUMS.
VARIATION IN THEIR STONES.
CHERRIES.
SINGULAR VARIETIES OF.
APPLE.
PEAR.
STRAWBERRY.
INTERBLENDING OF THE ORIGINAL FORMS.
GOOSEBERRY.
STEADY INCREASE IN SIZE OF THE FRUIT.
VARIETIES OF.
WALNUT.
NUT.
CUCURBITACEOUS PLANTS.
WONDERFUL VARIATION OF.
ORNAMENTAL TREES.
THEIR VARIATION IN DEGREE AND KIND.
ASH-TREE.
SCOTCH-FIR.
HAWTHORN.
FLOWERS.
MULTIPLE ORIGIN OF MANY KINDS.
VARIATION IN CONSt.i.tUTIONAL PECULIARITIES.
KIND OF VARIATION.
ROSES.
SEVERAL SPECIES CULTIVATED.
PANSY.
DAHLIA.
HYACINTH.
HISTORY AND VARIATION OF.
[THE VINE (Vitis vinifera) (Grapes).