This study animed to examine the relationship between crown development and cambial activity in the stem of broad-leaved trees. Hence the effects of sprouting on xylem formation at the branch of six diffuse-porous species were observed. The following conclusions were obtained. 1) The newly formed sprouts influenced the cambial cell activity in the decapitated branches, and the cambial activity intiated at the bases of the sprouts and extended toward the lower parts of the branches(Figs.3-7). 2) ln egonoki(Sytrax japonica)and yamazakura(Prunus jamasakura), the secondary cell wall formation of vessel elements initiated and then a few of the surrounding cells followed(Figs.10 and 11). In the other four species, nejiki(Lyonia ovalifolia), Kuroki(Symplocos lucida) , hime-yuzuriha(Daphniphyllum teijsmnni) and yamamomo(Myrica rubra) , the secondary cell wall formation of xylem components except ray cells initiated simultaneously(Figs.8 and 9). 3) As a result of observation on the branch shown in Fig.12, the diameters of earlywood vessel elements formed in the current year were smaller than those in previous year. Hence the decrease rates of the area of the individual vessel element in transverse section were examined in six species. The results indicated that decrease rates of deciduous species were higher than those of evergreen species(Fig.13).
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