Several of the species in this small genus are presumed extinct, as a result of coextinction with their primary pollinators, the Hawaiian honeycreepers.

Species in this genus are large shrubs or small trees, up to 7 metres (23 ft) tall, with nearly circular leaves.

The lateness of its discovery by western botanists indicates that Hibiscadelphus was already rare by the time Europeans arrived in Hawaiʻi.

Four species - H. bombycinus, H. crucibracteatus, H. giffardianus, and H. wilderianus - were only ever known from a single individual in the wild.

The widespread destruction of dry forests, both before and after European contact, was also a major factor.