サクラの研究 (第2報)

Abstract

1) The external morphological characteristics of about 130 seedlings of Prunus yedoensis were studied. A few typical P. lannesiana var. speciosa and P. subhirtella var. pendula form. ascenders were found among them and many others, ranging from speciosa to ascenders with wide distribution of various character combinations. Needless to say, a few P. yedoensis-like seedlings were also found.2) Fourteen hybrids between speciosa and ascendens grew well. Although they showed minor differences from each other, they belonged all to the yedoensis group from the morphological point of view. But they had larger leaves and flowers and more stamens than P. yedoensis, and the flower color of all plants except one was of a fainter pink than in P. yedoensis.3) Hybrids between P. lannesiana var. speciosa and P. subhirtella var. pendula had more delicate branches and a little smaller leaves and flowers than P. yedoensis. In general P. yedoensis may be assumed to be a hybrid between speciosa and ascendens rather than between speciosa and pendula.4) Nineteen hybrids between speciosa and yedoensis were observed. In the hybrids between speciosa and ascendens, hairiness of leaves, peduncles and calyxes, and umbelled inflorescence were assumed to be dominant to hairless and corymb, respectively. In all hybrids mentioned above, these dominancies were also recognized.5) Funabara-yoshino, which was found on Funabara-pass in Izu, had somewhat larger flowers and leaves and a few more stamens than P. yedoensis, but was very similar in the other characters to P. yedoensis and showed heterosis like P. yedoensis. Therefore this flowering cherry tree is also assumed to be a new natural hybrid between speciosa and ascendens.6) Kurama-zakura which has been clutivated in Kumamoto since long ago has leaves and flowers somewhat larger than those of yedoensis and its branches are slightly bent. But the other characters and appearance of heterosis are the same as in yedoensis. Accordingly this tree may be another hybrid between speciosa and ascendens.7) Midori-yoshino (P. yedoensis var. Nikaii Honda) has been cultivated in Hagi from Edo-period but is not encountered there now. All characters of these specimens are identical with those of yedoensis, except one character, namely white petal color. This plant is also assumed to be a hybrid between speciosa and ascendens and might have orginated in Izu and have spread as a garden plant from there. 8) I found some trees which could presumably be the offspring of yedoensis in Izu, Boso and Noto. Similar plants were found by some taxonomists. Some of them may be the offspring of yedoensis itself and the others may be that of the other hybrids of the same origin.