The generic name Hibiscus is derived from hibiscos, the Greek name for mallow. The specific and subspecific epithet kokio comes from the Hawaiian name for this hibiscus. The subspecies is named after Harold St. John (1892-1991), a professor of botany at University of Hawai'i Mānoa from 1929 to 1958 and a prolific field botanist, credited with discovering hundreds of new species.
Hibiscus St. John is almost in constant bloom year round. Flowers can be orange to orangish-red or, more rarely, yellow. The petals sometimes have a deeper-colored basal spot but often do not.
A Tropical Garden Flora by George W. Staples and Derral R. Herbst