Cottage Gardener, Country Gentleman's Companion and Poultry Chronicle, 24: 253-255 (July 24, 1860)
CROSSING FLOWERS
Donald Beaton

"WHERE there is a will there is a way," as the old saying goes; but a way without a willingness, on my own part to tread it, has opened up the distance at which speculation and practice work from each other in the crossing of flowers in the last number of THE COTTAGE GARDENER. And after the earnest request from the owner of the Yellow Polyanthus which comes true from seeds, I can hardly refuse some thoughts and some corrections on the common errors about crossing which obtain ground in the writings on the science of gardening through all our books. Like every other labourer, the labourers in this science have adopted wrong notions on the working of it, by jumping at conclusions from stray glimpses of the facts which were recorded upon incomplete evidence and upon certain trials which have not been proved. And science, or the labourers in this branch of it, are now on strike as surely as ever the workers in the building trade have been; and it is not in the nature of things that they should sign the "document" of their masters, the cross-breeders, until they can perceive the relation between facts on the one hand and fables on the other. No need to tell of masons, and plasterers, and "them" sort of people, till we ourselves can appreciate and show the value of practice and manipulation in conjunction with the branch of science which places the results on a natural basis.

The Prince Consort, in his presidential charge to the Statistical Congress the other day, said that the first and fundamental effort of every branch of science should be to adopt a uniform explanation of the terms it made use of: therefore, on that assumption, our branch is still on strike about the "document,"— about the definitions which the cross-breeders draw from the bosom of Nature, as it were. The labours of the cross-breeder compel the botanist to reconsider his arrangements, and to build them on n natural basis, like his own experiments. It was feared at first that the labours of the former would rather confound than assist the efforts of science; but experience did not affirm the point. The whole weight of science goes to prove the first and firmest rule of the cross-breeder—that plants from two natural genera cannot be crossed. In all other points science and practice are at variance as to the ways and means for crossing, and to the definition of many of the terms which are necessarily employed to convey the moaning of our dealings of crossed and crossing flowers.

*Leschenaultias and Wheat are so fertilised.

"The pollen is never shed from the anther of the stamen until the stigma of the pistil is fully developed to receive it," is the first rule given by science to the student in cross-breeding. Nature tells him a very different tale, as much as to say, "In order to keep down mental pride, I have so arranged that the presence or absence of stamens and pollen, and the progress of the growth and ripening of pollen have no effects whatever on the development of the pistils and stigma. I produce and ripen the pollen, and effect my process of fertilisation while the flower is yet in the first stages of a flower-bud;* and I work on gradually from that point, keeping the relative development of anthers and stigmas as much apart as if each of them were a member of a different plant, and as if my intention were never to allow a stigma to be fertilised by the pollen of the same flower. It is by ripening and dispersing the pollen of some particular plants before the stigma of any particular flower of them is ripe enough for effecting self-fecundation, that I am enabled to keep them from degenerating; and not only so, but that is my mode of improving races as much as of keeping them in their generations free from that degree of debility which would render them an easy prey to more powerful and competitive neighbours. In your kingdom among animated nature, I have given sight and smell as means to the same end."

That is how Nature speaks to Science on the very first lesson on cross-breeding. Therefore, he who goes to cross on scientific data, will soon find he is at cross purposes with Nature.

The gaping of the stigma when the pollen is about to fall, and at that time only, may be observed in the Heartsease. This view of crossing is taking it in the easy mood, but in the wrong tense. Stigmas which are so formed as to resemble gaping in any stage gape at all stages, from the nascent flower-bud to the time of natural maturity for the reception of pollen; and some gape on from the nascent to the point of puberty. Split flower-buds of the Leschenaultias and you will find the stigma with a gaping mouth wide as that of a young cuckoo, and open day and night till the anthers discharge their dust in it in secret. When that is effected the mouth closes; and by the time the flower opens all traces of stamens, anthers, and pollen are gone. Thousands this week or month can prove what I say.

In the great majority of such instances as are likely to come before the amateur, the age of puberty in the stigma is a mystery and a guess, there being no sign to indicate it perceivable by any ordinary lens. In the Rhododendron and Lily, and kinds with kindred styles and stigmas, the auspicious moment is known by a viscid fluid on the surface, and that fluid remains u long as the member is capable of fertilisation and no longer. The instance of the fluid drying up at noon, and reappearing each morning on the stigma of Amaryllis formosissima, or on any other stigma, is contrary to Nature also. No flower has more baffled practitioners than that of this Jacobean Lily. I have had a thousand of them under ten or a dozen kinds of trials, and in a space running off twenty-eight years; and the recurrence of the genital, as Gilbert would say, after it once dried off, never recurred in any one flower, nor in any other flower that I ever handled.

Mr. Knight's theory that the seed-vessel is not altered in appearance by impregnation from another plant, I thought and accepted as decided by experience; but l recorded this spring an instance to the contrary, which is capable of proof at anytime. The pods of Imatophyllum miniatum stand erect as the umbels of flowers, and the pods of I. cyrtanthiflorum hang down as the flowers do. By crossing the two, the pods of the former become as pendent as those of the latter—the most curious thing I know of among plants.

When you depart considerably from the wild types of our cultivated kinds or species, the influence of crossing is not so easily predicted; and when you reach the stage at which either of the parents lose their specific influence—lose their power of reproducing themselves by seeds, you can never predict the appearance, or the beauty, or markings of any of the seedlings.

In Geraniums and Calceolarias the leaf and the colour of the flower go more after the pollen parent than not; but the rule is not absolute in any genus that has yet been proved. The seedlings take the habit of the mother if the father and mother are of the same constitutional strength; not otherwise in any instance within my knowledge. I am at this moment making practical use of this very point.

Science puts it down as a rule, that if you cross two plants the seedlings must of necessity be intermediate in all their ways and looks; but Nature is very different indeed. First of all they would need to be near the original types; and, secondly, both must be of equal strength under equal circumstances, else it is ten to one if their offspring are intermediate. In all our common flowers the strength and the colour of the father, and the habit of the mother, are seen ten times to every instance of a perfectly intermediate degree, and both will get less and less to be relied on as the crossing of kinds is multiplied.

The doctrine of superfoetation has been pushed to its limits by Dr. Herbert and myself from 1836 to 1848, and neither of us believed one word of it. We could not produce the faintest trace of it. Hundreds of self-seedlings, without crossing, come as if they were of several parentages on the pollen side; and I am satisfied that scores of reputed crosses and crossings are of such origin, and merely an account of the trials that were made instead of the result obtained. No flower on earth is more easy to prove by if more than one pollen can influence a cross than any of the common Geraniums. Their stigma is parted into five parts, and each part rolls back from the rest, or from the centre; and there are five seeds for every flower, corresponding to the five divisions of the stigma, or mother, as we say. Now, by applying five kinds of pollen, one kind to each division of the stigma, it is easy to conceive the possibility of each seed being influenced by that pollen only which dusted its corresponding division; and if the scientific explanation of the process by which the pollen reaches the ovum, or skeleton seed, were correct, superfoetation would be inevitable, and five kinds of progeny must be obtained from that flower so operated upon. The Hibiscus is the next easiest flower to prove that superfoetation and the explained progress of the pollen to the ovary are both on a baseless foundation. I believe, from my own experience, superfoetation among vegetables is simply impossible; and that implies, also the impossibility of the pollen passing in grains in tubes of extreme tenuity to the embryo seed, which is the way it is explained by scientific men.

Pollen tubes grow at different rates. Growth rate tends to align with vigor of the pollen parent. Beaton's results probably would have been different if he applied the various pollens at different times. That is, the pollen that sired all the seedlings in one cross could have been applied a 12 or 24 hours after some other pollen had been added

The way I conceive the pollen must act in order to give the results with which many are quite familiar is this—for there is no other way of accounting for such results as we obtain. The pollen dust is in grains, like gunpowder; but the grains are inconceivably small. These grains swell on the application of moisture, and burst at a certain stage of swelling, and the substance melts and is absorbed in the moisture as sugar is in tea or coffee. In every part of a plant, tree, or flower, from the tips of the extreme roots to the farthest-off leaf and petal, there is a constant moving of fluid, and the fluid is constantly changed in its nature; and there is a natural turn, or condition of the fluid, for every natural requirement of the system of which the plant is composed; and one condition is the fulfilment of the original mandate to increase and multiply by seeds. The viscid fluid on the stigma is the last condition required, and in that condition it is incapable of evaporation by the ordinary heat of the sun. Like other fluids, it cannot come there by chance, only by the usual process of circulation. The pollen sticks in that viscid fluid as flies stick in treacle; it cannot pass through it, or part from it; but it swells and bursts, and its contents are absorbed on the summit of the stigma. The passages in the style, from the stigma to the ovary, allow of the circulation and the return of this viscid fluid, now mixed with the contents of the pollen grains. Were the process different, superfoetation might be possible. But now see the barrier which hindered the influence of the five kinds of pollen on the five divisions of the stigma of a Geranium. The five kinds gave their contents equally to the fluid, but the fluid is not visible in this kind, and the one of the five which had the nearest affinity, as a chemist would say, to the mother, took the lead, and neutralised the effects of the other four.

In Nature and in the wilderness it was a wise provision for covering the face of the earth, that the anthers of flowers should ripen and discharge their contents before the stigma was sufficiently ripe to absorb it; thus compelling every flower to be impregnated by another flower on the same plant, or from another plant within the degrees of consanguinity. The earth was thus very early clothed after the dispersions by the flood. The origin of species was then specially founded, and their subsistence to the after ages of the world has been partly owing to their power of selection, as Mr. Darwin says, but in a much greater degree by the capacity of the viscid fluid to retain the influences of the stronger member of the same kindred; because, as we have seen, and as I have proved in scores of instances, and as any of us can now prove in one month, that out of five kinds only one kind will ever take the lead: so in the preservation of kinds, which is a better word than species, its own pollen does not fertilise one flower out of one thousand. Another flower from the same branch, or truss, which is later in ripening its pollen does the business; and if the stigma is within the influence of five plants, or five hundred plants of the same kind, not one of them is capable of taking the lead but the one which is the most perfectly developed and the strongest; and I have made use of that very circumstance since 1838; and I am perfectly well satisfied that the contrary cannot be proved by direct experiments. The origin and the power of sustaining species to the end of time is just as familiar to me as my own origin, which my dear grandmother never ceased to dun into my ears while she applied the sustaining power up to the cramming point.