Hibiscadelphus

Hibiscadelphus is a genus of flowering plants that are endemic to Hawaii. It is known by the Native Hawaiians as hau kuahiwi which means "mountain Hibiscus". The Latin name Hibiscadelphus means "brother of Hibiscus". It is distinctive for its peculiar flowers, which do not fully open. Hibiscadelphus is in the family Malvaceae, subfamily Malvoideae. Several of the species in this small genus are presumed extinct, as a result of coextinction with their primary pollinators, the Hawaiian honeycreepers.

==Description== thumb|Flower of Hibiscadelphus giffardianus, showing the unusual "unopened" flower thumb|Fruit of H. giffardianus thumb|right|Flower of H. x puakuahiwi, possibly the last tree. It has the large flowers of H. giffardianus but the yellow color of H. hualalaiensis. Hibiscadelphus was first described by Austrian-American botanist Joseph Rock in 1911 on the basis of the species Hibiscadelphus giffardianus. Species in this genus are large shrubs or small trees, up to tall, with nearly circular leaves. The genus is characterized by flowers that never open to the flat form of Hibiscus, but remain folded together in a tubular form. This is presumed to be an adaptation to pollination by honeycreepers. The fruits are rough capsules containing up to 15 hairy seeds.