They are shrubs or small trees with evergreen foliage and smooth red or orange bark, typically reaching 10–20 m (33–66 ft) tall and up to 1 m (3 ft) in trunk diameter. The leaves are opposite, oval, 1–5 cm long and 0.5–3 cm broad, entire, glossy dark green, with a spicy scent if crushed. The flowers are 2 cm diameter with four white petals and numerous stamens; the fruit is a small purple or black berry 1 cm diameter.
The genus name derives from the Mapuche (Native American) name for a related species, Amomyrtus luma. Though it grows slowly, luma wood is very dense and durable.