Cephalanthus is a genus of flowering plants in the family Rubiaceae. There are about six species that are commonly known as buttonbush.

Description

They are shrubs or small trees growing to 5 - 15 m tall. The leaves are simple, arranged in opposite pairs or whorls of three. The flowers form a dense globular inflorescence.

Distribution and habitat

Cephalanthus occidentalis is native to the eastern United States and Canada. The others occur in tropical regions of the Americas, Africa and Asia. Two species are known in cultivation.

Systematics

Cephalanthus was named by Linnaeus in Species Plantarum in 1753. The generic name is derived from the Ancient Greek words κέφαλη (kephale), meaning "head", and ἄνθος (anthos), meaning "flower".

Taxonomy

Cephalanthus is the most basal genus in the tribe Naucleeae. Some authors have segregated it into its own monotypic tribe. The type species is Cephalanthus occidentalis.

Species

Fossil record

16 fossil mericarps of †Chephalanthus pusillus have been described from middle Miocene strata of the Fasterholt area near Silkeborg in Central Jutland, Denmark.