252 



The Journal of Heredity 



NEW VARIETIES BY BUD VARIATION 



The oldest Wase tree, now about 70 

 years of age, is found in the village of 

 Aoe, prefecture of Oita. Three younger 

 plants from which the present com- 

 mercial variety was taken, also exist in 

 the same village. All of them are 

 grafted, and we know not whence they 

 came; but the discovery of almost 

 exactly the same form of orange on a 

 branch of an entirely different kind of 

 Satsuma, threw a new light upon the 

 quest'on of the origin of varieties. In 

 the village of Tsukumi, not far from 

 Aoe, a farmer discovered very early- 

 maturing fruits borne on an ordinary 

 Owari Satsuma tree. A careful study 

 of the fruits and flowers of this tree by 

 the writer proved this early variety to 

 be identical in all respects with the 

 Wase originating at Aoe. It was a 

 clear case of progressive or beneficial 

 bud-variation. It is of great interest 

 to note that variations of this kind are 

 by no means very rare; they are, on 

 the contrary, rather to be expected, as 

 a careful study of the phenomenon has 

 shown. In the villages of Hisatomo 

 and Ocho, in the prefecture of Hiro- 

 shima, on the inland sea, other strains 

 were found which had likewise origi- 

 nated from bud variation. The charac- 

 ters of the new Wase growing in these 

 places, are slightly different from one 

 another, as well as from the Aoe and 

 Tsukumi Wase. In four different 

 villages of the prefecture of Shidzuoka, 

 I found different strains of Wase, 

 which had undoubtedly originated 

 from bud variations. These bore a 

 general resemblance to one another, 

 but when carefully studied, all of them 

 proved to be distinct. Some of these 

 new varieties have been propagated 

 by grafting and their progenies have, 

 in all cases, been found to possess the 

 new characters without alteration. 

 Commercial orchards of the Wase 

 variety, descended from trees of the 

 village of Aoe, also continue in the 

 main, true to type, but it is especially 

 interesting to note the tendency of the 



Wase to revert to the parental Owari 

 form.^ 



TENDENCY TO REVERT 



Early growers of commercial Wase 

 trees noticed that a certain percentage 

 of their plants did not come out as 

 Wase, but reverted to the Owari type; 

 and they suspected that there was some 

 mistake made in selecting the bud wood. 

 Later it was observed that Wase trees 

 sometimes send forth branches bearing 

 leaves and fruits quite different from 

 those of the typical Wase, but closely 

 resembling the ancestral Owari forms. 

 These are clear examples of vegetative 

 reversion, which is known to occur only 

 in a limited number of cases on bud 

 sports, or varieties resulting from mu- 

 tation . A careful study of this phenome- 

 non convinced me that it is very 

 common in the Wase of Aoe. To cite 

 an extreme case, twenty-seven trees 

 out of one hundred were found to 

 bear branches having the character- 

 istics of the ancestral form on which the 

 variety had appeared as a bud varia- 

 tion. This demonstrates the impor- 

 tance of selecting with the greatest 

 care the buds to be used for propagat- 

 ing. 



Whether the Wase is a real somatic 

 mutant or a "chimera" we know not. 

 If a chimera, its reversion to the 

 ancestral form can easily be explained ; 

 for most chimeras behave in the same 

 way. At the same time, we must 

 expect the occurrence of unchangeable 

 Wase by a similar procedure. We 

 do not know whether or not absolutely 

 constant Wase exists; but of one thing 

 we are quite certain, that bud variation 

 and vegetative reversion are associated 

 phenomena in plants belonging to the 

 genus Citrus, and this may also be true 

 with mutants of other plants not in- 

 cluded in the family Rutaceae, though 

 in this connection our knowledge is still 

 scanty. Variegated leaves associated 

 with striped fruits originate by bud 

 variation; and it is well known that in 

 these variegated forms reversion to 



^ Tanaka, T. a New F'eature of Bud Variation in Citrus, 

 of Agriculture. 1922. 



Circular 206, U. S. Department 



