White hydrangea-like flowers have begun to open in the Ninomaru grove south of Palaceside Building in the East Gardens of the Imperial Palace — deutzia (noriutsugi), cone-shaped unlike most round hydrangeas.
Written 糊空木: hollow sponge-like stems gave "空木"; inner bark mucilage was used as paste for papermaking — "糊." With kozo paper, deutzia paste keeps sheets from sticking and resists rot.
In autumn the calyx backs turn red against white blooms. After fading, brown clusters persist into the next year. In some regions parents tell departing daughters: "Don't return until the deutzia flowers are gone" — perhaps echoing "long-lived flowers, yet many partings."