A Preliminary Note on the Histological Studies on the Stem of Mulberry Tree with Special Reference to its Color

Abstract

1) From the comparative observations on the stem color of mulberry trees belonging to 285 races grown in Tokyo district during winter, we have distinguished 17 different colors which may be grouped into 4.
2) Histological studies showed that the color of stem depends upon the color and number of cells in cork, cortex and epidermis layers, the first are suberised and are brownish, the second contain chloroplasts and are greenish, the last are grayish owing to wax and cutin covering the surface
3) The cork and cortex layers together give the ground color of the stem which is classified into 4 groups and the epidermis layer modifies it into 17 sub-groups.
4) When the waxy substance deposits on the whole surface of the stem, it shows even grayish color, while it is not so even when waxy substance depoits on only one part of the stem, e. g. on one side of the stem directing to the north.
5) In early spring when the ascent of sap begins, the color of stem becomes lighter owing to the change of green color of cortex layer.