54 



Garden and Forest. 



[January 29, 1890. 



exceptions which' invite unlimited study and experiment with 

 a promise of some interesting results. 



Although the physiological reasons for these phenomena of 

 growth are as yet so little understood, the visible results 

 brought about by the practices of. the horticulturist are often 

 very striking and well marked. . 



Considered in its practical aspect it is surprising to find, after 

 such a long period of usage, so. few authoritative accounts 

 indicating the full value of any stock for any special purpose. 

 The French horticulturists seem,- more than others, to have 

 made advances in the practice of grafting and the study of its 

 results, and some of their manuals and notices of the subject 

 contain much valuable information for the amateur. Un- 

 doubtedly a great impetus has been given to the study by the 

 practice, in recent years, of grafting the wine-producing 

 grapes of France upon the roots of American species in order 

 to check ravages by Phylloxera. 



We know that when scions of some species are grafted 

 upon stocks of an allied species, or sometimes even on a 

 different plant of the same species, an increased vigor often 

 results. Michaux states that the striped Maple (Acer Pennsyl- 

 vanicum) when grafted on stock of the Sycamore Maple (A. 

 Pseiido-platamis) increased to four times its natural size. 



There is almost no limit to the possibilities of inter-grafting 

 between plants of the same species ; but how far grafting may 

 be successfully and economically carried between different 

 species or allied genera is a matter of which comparatively 

 little is known. The practice of grafting the Pear upon stock 

 of the Quince (Pyrus Cydonia) is one of the few cases where 

 long usage has made the results familiar to all, and the differ- 

 ence between the Pear grafted upon Quince stock and a Pear 

 grafted on seedling Pear-trees is well marked. Thus it has 

 been found, as a rule, that successful grafting is fully as easy 

 on Quince as on Pear-stock ; that growth on the Quince-stock, 

 though more vigorous the first year, becomes less vigorous 

 in succeeding years than when grafted on Pear-stock ; when 

 grafted on Quince fruit may be produced in two or three years, 

 while on Pear-stock it cannot be expected for at least five or 

 six years. The fruit is usually finer, larger and relatively 

 more abundant on Quince-stock, but the trees are dwarfed, 

 and, as a rule, are short lived, while they become large and 

 are comparatively long lived when grafted on Pear. It is 

 also noticed that the graft on Quince increases in diameter 

 much faster than the stock and that the joining of the stock 

 and graft is never so perfect as it is when the Pear is grafted 

 on Pear stock. 



Other points have been noted, and although much depends 

 upon climate, soil and other conditions, and still more upon 

 the character of some varieties of the Pear, the foregoing ob- 

 servations may be taken as an example of what is desirable in 

 the knowledge of the value, as stocks, of hundreds of our 

 trees, shrubs and vines. To know what stock will produce 

 the best, longest lived plants of a variety grafted upon it, and, 

 at the same time, give the most satisfaction in the abundance 

 and quality of the flower or fruit, is certainly of great import- 

 ance to the horticulturist. It seems to be true that certain 

 stocks have an influence in hastening or retarding the leafing, 

 flowering and fruiting of some plants ; and the hardiness of 

 some rather tender species often appears to be increased by 

 grafting upon hardy stocks, probably because the wood 

 becomes riper and better matured before winter frosts. 



No regular series of experiments in grafting has as yet been 

 attempted at the Arnold Arboretum ; but Mr. Jackson Dawson, 

 the propagator, has tried a great variety of stocks, and while, 

 as was to have been expected, many of them have so far 

 proved failures, others appear successful and worthy of notice. 



The following notes made within a few weeks among the 

 plants in the collections and nurseries are given, because they 

 may be of interest to others working in the same direction. 

 Among such young plants time alone will tell what the 

 ultimate result and value will be. 



One of the most interesting cases is that of five specimens 

 of western Larch (Larix occidentalis), all growing near each 

 other in the same soil and receiving the same treatment. 

 Three of the specimens were produced from seed collected in 

 Oregon and sown in November, 1881. Two of them are five 

 feet and the other three and one-half feet in height, and all 

 have stems three inches in circumference at one foot from the 

 ground. The greatest spread of branches is three and one- 

 half feet. 



The other two plants were grafts taken from some of the 

 above lot of seedlings in January, 1884, and grafted upon stock 

 of a Japanese Larch (L. leptolepis). 



These are now seven feet high, and have stems six inches 

 in circumference at one foot from the ground. The greatest 



spread of the branches is five and a half feet. The point 

 of insertion of the graft is not apparent in either plant. 

 The seedling plants lose their leaves a little earlier, and are 

 much more straggling in habit than the grafted specimens. 

 Until within a few years it was not considered practicable to 

 graft the Hickory. Young seedling and grafted specimens of 

 these trees grown under the same conditions, show, in some 

 cases, a little advantage in favor of grafting. As yet the only 

 stock used at the Arboretum has been Hicoria ovata (Carya 

 alba). A variety of Hicoria ovata grafted in March, 1887, is 

 now over two feet high, and of four seedlings planted beside 

 it, the seed of which was planted in October, 1883, three 

 specimens are two and one-half feet high and the fourth over 

 one and one-half feet. The scion of the grafted plant was 

 only three or four inches long when inserted in the stock. 

 No marked difference in size or vigor has as yet appeared in 

 seedling and grafted specimens of Hicoria sulcata (Carya 

 sulcata) now six or seven years old. The Hickories offer a 

 field for interesting experiments to determine which are the 

 best stocks for grafting purposes. 



Among the Oaks, the English Oak (Quercus Robur) is found 

 to be the best for all purposes as a stock. The only plants 

 measured for comparison were two plants, growing side by 

 side, of the dwarf Georgia Oak (Q. Georgiana). One of these, 

 grown from seed collected in Georgia in November, 1876, is 

 four feet high, and the other, grafted on roots of young plants 

 of Q. Robur in January, 1884, is now over seven feet in 

 height. The stock in this case increases in diameter faster 

 than the graft. The seedling plants have been occasionally 

 partially killed in winter, while the grafted plants appear to 

 sustain no injury. 



Another interesting case is that of a south-western Ash 

 (Fraxinus anomala), in which grafted specimens again show 

 greater hardiness and faster growth over those not grafted. 

 Of two healthy plants growing side by side under exactly the 

 same conditions," the seedling plant is now four and a half 

 feet high. The seed of this was collected in Utah and sown 

 in 1874. The other plant is from a graft taken from the 

 above lot of seed-grown plants and grafted on a seedling of 

 the common White Ash (F Americana) in February, 1882. 

 It is now over nine feet high and appears vigorous and hardy, 

 while the seedling plant has often been injured in winter. 

 Other plants of these lots show the same proportionate rate 

 of growth, vigor and hardiness. The various species of 

 Amelanchier and Cotoneaster grow vigorously when grafted on 

 the European Mountain Ash (Pyrus aucuparia), and the 

 former appears to thrive fairly well on stock of English 

 Hawthorn (Cratcegus Oxyacanthd), while the latter seems to 

 do very poorly. 



The Pear is commonly known to grow well on Crataegus, 

 but, no doubt, a great difference would be found in the value 

 of the various species of thorn for stock. Some varieties of 

 Pear, budded upon strong roots of the native scarlet Haw 

 (C. coccinea, var.), have been known to grow with extraor- 

 dinary rapidity and to produce large crops of fruit within 

 three or four years, but, in the cases which have come under 

 my notice, the stems of the Pear-trees increased in size 

 much faster than the stock, so that the disproportion became 

 very great and the plants died while quite young. 



The increased longevity and value of the Peach when 

 grafted on Almond. or Plum-stock is well known, and there 

 is reason to believe that stocks of the different species of Plum 

 would produce such varying results that they would be well 

 worth testing comparatively. 



The value and advantage of grafting many of our choice 

 varieties of Roses is now generally conceded, but there are 

 still differences of opinion as to the best stock for such 

 purposes. The Dog Rose (R. canina) and the stock known 

 as the Manetti are those in most common use. In recent 

 years the Japanese Rosa multiflora of Thunberg has been 

 employed to some extent as a stock, and, at the Arboretum, 

 a Japanese species recently described by F. Crgpin as Rosa 

 Waisoniana has been used with satisfactory results. Its pe- 

 culiar advantage as a stock over the old species in use and 

 over R. multiflora (of which it may be a form) lies in the fact 

 that the suckers and stray shoots from the stock may be at 

 once detected by the slender, long, narrow leaves which are 

 very different from those of all other Roses. Similarity of 

 foliage often renders it troublesome to distinguish the graft of 

 a Rose from the stock. Rosa Watsoniana appears to be less 

 vigorous in habit of growth than the other kinds used for 

 grafting purposes. The Japan Quince (Pyrus Japonica) grows 

 poorly on the English Hawthorn, and has refused to adhere 

 to Apple stock for any length of time. But the Chokeberry 

 (Pyrus arbtelifolia) thrives remarkably well on the European 



