Gardeners’ Chronicle, p. 293-294 (March 9, 1895)

HERBACEOUS GRAFTING

IN his book on the Art of Grafting, which is one of the horticultural classics, Baltet summarises the objects of grafting to be as follows: (1) to change the nature of a plant by modifying the woody tissue, the foliage, the blossom, or the fructification which would be produced naturally; (2) to promote the development of branches, leaves, flowers, or fruit in certain parts where they are deficient; (3) to restore vital activity to a plant which is weak or exhausted, by the transmission of new sap from another plant which is strong and healthy; (4) to unite the two sexes in plants which by nature are dioecious, thereby to facilitate fertilisation, or to transform completely the sex of a plant; (5) to preserve and to propagate a large number of varieties of useful or ornamental plants which cannot be reproduced by any other means.

The early history of the art will probably never be written. If the gradual development of grafting seem easy to trace inductively, it is more difficult to conjecture the circumstances which were the cause of its origin, even though it were by chance. It would be most interesting to know what plants were among the first to be grafted, and what were the results. Whether the primitive horticulturist became convinced of the advantages of grafting by continuous success from the first, or whether the art had to struggle for existence through ages of suspicion.

It seems natural to suppose that grafting was at first practised in connection with woody plants. Employed as a means to an end, the operation would presumably be found more attractive with plants of this nature bearing conspicuous flowers or agreeable fruit. It would also be found more easy of application, and the results more evident as well as more useful.

Although authoritative documents exist to show that grafting was known to the Phoenicians and Carthagenians, it has often been erroneously held that the herbaceous graft is of comparatively recent origin. It must, however, have also been practised from a very remote period, for Aristotle has recorded that he himself grafted a cultivated Artemisia upon a wild one. But the greater care required to graft herbaceous plants, and the apparently less important results to be obtained, would tend to the supposition that the herbaceous graft was not the earliest in point of time.

This assumption being made, it is, however, not easy to conjecture how much later in time was the art of grafting first applied to the herbaceous or to the more succulent stem. Suffice it to say that, perhaps because of the apparently smaller results to be obtained-the graft has hitherto been used to a very limited extent in connection with herbs and vegetables.

During recent years, however, the subject has been investigated, particularly in France, by many workers, with considerable vigour. Results have been reported from the Cornell University Experiment Station, New York State, where zonale Pelargonlums bloomed upon the common rose Geranium; and Coleuses of many kind, were used with uniform success, the scions of some of which were vigorous a year after being set. "Tomatos upon Potatos, and Potatos upon Tomatos also grew well, and were transplanted to the open ground where some of them grew, flowered, and fruited, until killed by the frost. The Tomato on Potato plants bore good Tomatos above and good Potatos beneath, even though no sprouts from the Potato stock were allowed to grow."

Chrysanthemums are commonly grafted in Japan, as was stated by Hayato Foukouba, the director of the Mikado's gardens, during his visit to the Paris Exhibition of 1889. The yellow and delicate Étoile de Lyon can, for instance, be grafted on the white-flowered and more vigorous Comtesse de Chambord. The practice is moreover not unknown in this country where several varieties of Chrysanthemums, which present certain kindred characters, are sometimes united on the same plant.

The researches made by M. Lucien Daniel, which have been fully reported in the Revue Générale de Botanique, have enabled him to state, not only that the graft is practicable to a considerable degree of success in connection with herbaceous stems, but that its effects, so far as is now known, tend to the inference of very important, if not definite, results.

M. Daniel grafted forty-six plants, which he succeeded in growing till fruit was produced, and which—without here enumerating the list at greater length—included such combinations as Peas on Beans, Cabbage on Kohl Rabi and on Turnips, Fennel on wild Carrot, winter Lettuce on wild Prickly Lettuce, Toad-flax on Snapdragon, Celery on Parsnip, Carrot on Parsnip, and vice versa.

His observations led him to certain conclusions regarding the herbaceous graft, among which may be named its lesser resistance to cold; its modification in size by the stock in most cases; and the depreciation, as a rule, of the quality of a cultivated plant grafted onto a wild one. M. Daniel also found root-grafting of herbaceous plants to be the most successful.

It was already well known that, under the influence of transpiration, herbaceous scions wither very quickly after the operation of grafting. But M. Daniel has observed that whilst certain plants of this nature wither only to die, others gradually revive, and that these conditions are dependent, to a great extent, on the thickness of the leaves of the plants.

He investigated this particular subject by making experiments on the Bean, which was selected as a type of thin-leaved plants, and on the Cabbage, which was taken as a type of plants with thick leaves. He grafted two Bean plants, and placed one of them under a bell-jar, and the other in the open, and compared both with a third, which was also kept in the open air, but which was not grafted. The unprotected Bean died after three days, through the effect of transpiration. The graft protected by bell-jar began to show signs of union after seven days, and although complete re-union eventually obtained between the stock and the scion, this Bean-plant died after fifteen days. The Cabbages, on the contrary, which were placed under similar conditions, overcame the effects of transpiration for a considerable period, and when, on account of the cold weather, the experiment was discontinued, their eventual successful growth seemed to be beyond doubt.

It would, therefore, appear, says M. Daniel, as regards thin-leaved herbaceous plants, such as the Bean, that if the equilibrium between the amount of water absorbed and that which is transpired be once destroyed, these plants die; but, as regards thick-leaved herbaceous plants, that they are better able to withstand the effect of abnormal transpiration, and that the grafting of such plants is not nearly so often followed by fatal consequences. B.

Daniel bibliography