Mamaki is a tree or shrub up to 30 ft tall. The bark is gray to reddish-brown in color. The leaves are dark green above and whitish below. The leaves are highly variable in size and shape, from 3 to 8 inches long, oblong to heart shaped, with reddish veins. The edges of the leaves are toothed. Flowers are small, white to greenish, and grow in the leaf axils. The male and female flowers grow separately but on the same plant. Flowers bloom year round. The fruits are small and white berries.
Mamaki trees and shrubs grow in wet forested areas. The bark fibers have been used to make cloth and rope. The fruits and leaves have been used for medicinal purposes and the leaves are dried and sold today commercially. Mamaki trees are used in landscaping and are the host plant for the Kamehameha butterfly caterpillars and sometimes the Green Hawaiian Blue butterfly.