Wednesday, December 30, 2009

Hibiscus arnottianus ssp. arnottianus

Hibiscus arnottianus | White Rosemallow, Kokio Ke'oke'o

Hibiscus arnottianus is one of the hibiscus species native to the Hawaiian Islands. It was used in the development of many of the Hibiscus rosa-sinensis varieties found today, and has produced many horticultural cultivars. It is also used as an understock when grafting hybrids, mainly because it is long-lived, hardy, and resistant to root-rot. A small tree or tall shrub, usually with dense foliage, the flowers have a wonderful fragrance. The blooms last for two days and are produced freely on short spurs from older wood. For this reason Hibiscus arnottianus is best left unpruned; however severe pruning (about halfway) in spring every four to five years is recommended to keep the plant healthy and in a nice form. An open sunny situation is best, with rich well-drained soil. Liberal water and fertilizer should be applied during the summer and fall flowering season.

Three subspecies of Hibiscus arnottianus are recognized:
ssp. arnottianus (photo above) is from O'ahu and has smooth leaves 4-10cm long. It grows at elevations of 390 to 2500 feet in the Wai'anae and eastern Ko'olau mountains of O'ahu.
ssp. immaculatus is native to Moloka'i and has a white staminal column and leaves with rounded teeth. The leaves are 4-10cm long and often have red veins and stems. The faintly fragrant flowers have white petals 8-11cm long. The flowers may be slightly pink or may age to pale pink. Hibiscus arnottianus ssp. immaculatus is found in only in four populations on Moloka'i. It is the rarest of all and is listed as an endangered species.
ssp. punaluuensis, the Punaluu Rosemallow is also native to O'ahu. This is the most common of the three subspecies. Its a robust plant with leaves up to 25cm long and comes from the Ko'olau Mountains at elevations of 650 to 2200 feet.

Historical Reference: But neither the delicate kokio- keokeo (Hibiscus Arnottianus), which is the subject of so many songs and legends, and which, with its white petals and rich pink stamens, used to drape the sides of rocky ravines, nor the red variety with which girls used to adorn their hair, ever had any struggle for existence till the goats came, who have made them both very nearly things of the past.

   All the year round: a weekly journal, Volume 38
   By Charles Dickens,
   Published by Chapman and Hall, 1886