Adina is a genus of approximately 12 species of flowering shrubs and small trees belonging to the family Rubiaceae, within the order Gentianales. The genus is native to East Asia and Southeast Asia, with species distributed across a broad arc from northeastern India and southern China west to Japan, Korea, and Taiwan, south through mainland Southeast Asia (Myanmar, Thailand, Vietnam), and into the Malay Peninsula, Borneo, Sumatra, Sulawesi, the Moluccas, the Philippines, and New Guinea.
Plants in the genus are characterised by inconspicuous terminal vegetative buds loosely enclosed by stipules that are divided (bifid) for at least two-thirds of their length. The corolla lobes are nearly valvate in bud, being subimbricate only at the apex. Anthers are basifixed and introrse, and the ovary bears two locules each containing up to four ovules. The common name "button bush" is applied to some members on account of the spherical, tightly clustered flower heads — a habit reflected in the genus name itself.
Adina was described by the English botanist Richard Salisbury in 1807 in his illustrated work The Paradisus Londinensis. The name derives from the Ancient Greek word adinos, meaning "clustered" or "crowded," a direct allusion to the compact globose inflorescences that typify the genus. The biological type is based on Salisbury's Adina globiflora, which is today treated as a synonym of Adina pilulifera, a species ranging from Japan and China to Vietnam. Molecular phylogenetic work has established that Adina is paraphyletic with respect to Adinauclea, a monospecific genus endemic to Sulawesi and the Moluccas, suggesting that the circumscription of Adina may require future revision.
Etymology
The genus name Adina was coined by the English botanist Richard Salisbury in 1807, derived from the Ancient Greek adinos ("clustered, crowded"), referring to the characteristic tightly packed globose flower heads. The type species was originally called Adina globiflora, a name equally evocative of the plant's rounded inflorescences.
Distribution
Adina species are native to East Asia and Southeast Asia, spanning from northeastern India and southern China west to Japan, Korea, and Taiwan, south through mainland Southeast Asia (Myanmar, Thailand, Vietnam), and into the Malay Peninsula, Borneo, Sumatra, Sulawesi, the Moluccas, the Philippines, and New Guinea.
Taxonomy Notes
Adina was first described by Richard Salisbury in 1807. Molecular phylogenetic studies have shown the genus to be paraphyletic over Adinauclea, a monospecific genus from Sulawesi and the Moluccas, indicating the two genera are not cleanly separated by evolutionary history. The type specimens Salisbury assigned to Adina globiflora are now subsumed within Adina pilulifera.
