Melastomataceae are perennial herbs with square (quadrangular) stems. Leaves are opposite, simple, and typically have three prominent veins, often without a leaf stalk (sessile). Flowers are bisexual and usually found alone or in cymes, with a floral cup (hypanthium) at the base. They are mostly actinomorphic, sometimes slightly zygomorphic. The fruit is a capsule shaped like a small urn.