In Akita district, Sugi has been divided into six types by the morphological characters of bark which are caused by deep splitting and dropping off of the outer tissue. From the standpoint of anatomy, there are no differences in these six types on the arrangement of phloem elements. Two groups have been found in the manner of dropping off of the outer bark; one drops off from the band of intercelluler spaces which has formed in living secondary phloem and the other from absission layer formed by destruction of phloem parenchyma when the function of phloem has lost.