The leaves are opposite, simple, obovate, blunt or rounded at the apex. The lower surface of the leaves is finely hairy with minute, golden, shiny glandular dots. Leaves may be from 5 to 14 centimeters long and from 4 to 8 centimeters wide. Three or four prominent, ascending, curved veins are present on either side of the mid-vein. Twigs are four-sided, finely hairy and brownish when young.
Flowers are perfect and zygomorphic.
The corolla is bluish or purplish, finely hairy outside with long hairs inside. Fruits are a purplish drupe which contains 3 to 4 seeds. Flowering has been observed between the months of May and July, and fruits are present in September and October. Seedlings have not been observed during status surveys of the species. Palo de nigua is endemic to the island of Puerto Rico.