The water elder is often multistemmed. Unlike other members of the genus, the leaves are opposite, instead of whorled. The leaves are long and narrow and may be entire or slightly toothed in the upper half of the leaf. The leaves may also be slightly sticky when young. The flowers are white, tubular, very small and borne in dense clusters from October to February. The fruit is a small capsule which can be found inside the calyx (January-May). Young branches and stems are four-angled. The bark is textured, reddish to grey-brown and peels in narrow strips. The main stem may be fluted.