Yellow hibiscus

Hibiscus brackenridgei can sometimes become a small tree growing up to 30 feet tall. In the garden, it is most often a 3 to 15 foot tall shrub with a diameter of 8 to 15 feet. Young plants have smooth tan trunks; the trunks of older plants have a wrinkled appearance. The fuzzy leaves have toothed edges, 3, 5, or 7 lobes, and are up to 6 inches long and equally wide.

The large flowers are 4 to 6 inches in diameter. They are yellow, generally with a maroon center, and form singly or in small clusters at the ends of the branches. The staminal column is yellow. Garnett reports that the flowers open between 2 and 4 p.m. and close between 9 a.m. and 1 p.m.

Spring through early summer is the main blooming season with occasional flowers during the rest of the year. Garnett reports a flowering season of January through March for the subspecies found on O'ahu. (Bornhorst 1996; Criley 1998; Criley 1999; Garnett 1988; Koob 1999; Wagner 1990).

Habitat and Geographic Range

Hibiscus brackenridgei is an endangered Hawaiian endemic plant and it is the official state flower of Hawai'i. It is native to dry forests and shrub lands at elevations from 400 to 2,600 feet. It is found on all the main Hawaiian islands except Ni'ihau and Kaho'olawe, but it is not common in any location. (Wagner 1990)

Propagation by Seeds

The seeds of Hibiscus brackenridgei are contained in 3/8 to 3/4 inch oval capsules. The capsule is covered with soft hairs. It is dry and tan when mature and opens to release the seeds. The seeds are 1/8 inch long, kidney-shaped, and covered with fine hairs.

The best germination rate is obtained from fresh seed. Hibiscus hybridize easily and the seedlings may differ from the parent plant. To ensure that the seedlings are not hybrids, hand pollinate the flowers. Using a paint brush, transfer pollen to the stigma of the flower and then enclose the flower in a bag until the seed capsule ripens. Bornhorst (1991) recommends hand pollination in the early morning. The germination rate for Hibiscus brackenridgei seeds decreases significantly after one year. Soaking the seeds is not necessary, but it will speed up germination. Soaked seeds germinate in about one week.