Monday, August 03, 2009

Gossypium tomentosum

Gossypium tomentosum | Hawaiian cotton, Ma'o, Hulu-hulu

Gossypium tomentosum (previously known as Gossypium sanwicense) is the only member of the cotton genus endemic to the Hawaiian archipelago. It forms a shrub up to 1.5m tall and wide, and is found growing on the dry and rocky coastal areas of the Islands, from sea level to 120m. The leaves have 3 or 5 lobes and are covered with silky white hairs (hence the name tomentosum), giving the plant a silvery, gray-green appearance. Flowers are bright yellow, up to 7cm across, usually borne singly. Gossypium tomentosum’s status in the wild is considered vulnerable.

Genetic studies indicate that Hawaiian cotton is closely related to the American species of Gossypium used for commercial cotton production. Its ancestor may have come to the islands centuries ago as a seed in the wind, in the droppings of a bird, or lodged in floating debris. Gossypium tomentosum’s short, reddish brown seed hairs are unsuitable for spinning or twisting into thread, so it has never been used for producing cotton. Gossypium tomentosum is known by two Hawaiian names: Ma'o (“yellow-green”) and Hulu Hulu (hairy-hairy). It was used by the ancient Hawaiians as a source of green-yellow kapa dye.

Historical Reference: Two native species of cotton may here be mentioned as belonging to the fiber plants, though the natives, unacquainted with spinning and weaving, made no use of them. Again, the very short fiber failed, perhaps, to attract their attention: Gossypium tomentosum, a spreading shrub 4 to 6 feet high, hoary, with soft, white tomentum, three to four seed in each valve, which are enveloped in a finely adhering tawny wool, fibers of which measure 0.3 to 0.6 inch in length. Gossypium drynarioides (Kokia drynarioides), a small tree 12 to 16 feet high, with red flowers and each cell of the capsule with one seed covered with short, brownish wool. This plant is rare on the islands and doomed to extinction unless cultivated, since the capsules are imperfectly dehiscent and the seed are held and are eaten by worms, thus preventing reproduction. Again, cattle are extremely fond of the foliage and fruit and quickly destroy them in pastures.

   Bulletin, United States Office of Experiment Stations, Issues 94-99
   United States Office of Experiment Stations
   Publisher G.P.O., 1901