Tropical Plant Database - Plant Details

Gossypium tomentosum is a shrub that grows from 0.5 to 1.5 m tall and can spread extensively forming clumps from 1.5 to 3 m in diameter. The leaves are wider (3-10 cm) than they are long with 3 or 5 lobes that are rounded to pointed at the apex. The venation of the leaves is palmate meaning the primary veins diverge from a single point at the base of the leaf. The leaves have branched hairs on both the top and lower surface which gives them a silvery, gray-green appearance. The flowers are bright yellow (about 6 cm in diameter) and are typically borne either singly or in clusters of 1-3 flowers in the leaf axils. Each flower is subtended by an involucre made up of three bracts (15-25 mm long) with margins that are irregularly and sharply toothed. These bracts can also be seen during the formation of the fruit which is a woody capsule that is 1.2-1.8 cm long. This capsule dries and breaks open when it is mature to release 6-12 seeds each of which is 5 mm long and is covered by reddish brown fibers.

(Wagner, W. L., Herbst, D. R., and S. H. Sohmer. 1999. Manual of the Flowering Plants of Hawai`i. Revised Edition. Volume 1. Bishop Museum Special Publication 97. University of Hawai`i Press, Bishop Museum Press, Honolulu, Hawai`i.)

Gossypium tomentosum is currently found in remnant fragments of dry coastal shrublands on the leeward side of O`ahu, Maui, Kaho`alawe, Lana`i and Ni`ihau. It is no longer found on Kaua`i although it was historically found there. Currently research is being conducted on the potential for introgression of genetic material from the cotton species that have become naturalized in Hawaii, Gossypium hirsutum and G. barbadense.

(Animal and Plant Health inspection Service, USDA. 15 Apr. 2006.
http://www.aphis.usda.gov/brs/cotton.html.)
(DeJoode, D. R. and J. F. Wendel. 1992. Genetic diversity and origin of the Hawaiian Islands cotton, Gossypium tomentosum. American Journal of Botany. 79(11): 1311-1319.)

The flowers of ma`o produced a yellow dye that was traditionally used in kapa production. Both the flowers and the seeds are used for making beautiful leis.

(Abbott, I A. 1992. Lā`au Hawii`i: Traditional Hawaiian Uses of Plants. Bishop Museum Press, Honolulu, Hawai`i.)

Gossypium tomentosum is an endemic species meaning that is only found in Hawai`i. It is found in dry coastal shrublands from sea level to 120 m on on the leeward side of all the main islands except Hawai`i and Kaua`i. Ma`o flourishes on sand or weathered clay and rocky substrates in this harsh environment which receives less than 500 mm of rainfall annually and is subject to large temperature fluctuations.

(Wagner, W. L., Herbst, D. R., and S. H. Sohmer. 1999. Manual of the Flowering Plants of Hawai`i. Revised Edition. Volume 1. Bishop Museum Special Publication 97. University of Hawai`i Press, Bishop Museum Press, Honolulu, Hawai`i.)

The oil extracted from the New World species Gossypium barbadense and Gossypium hirsutum is purified for the production of cottonseed oil. The semi-toxic oil gossypol is produced in glands in the seed and must be processed in order to render this oil edible.

(Simpson, B. B. and M. C. Ogorzaly. 2001. Economic Botany: Plants in our World. 3rd edition. McGraw-Hill, New York.

Gossypium tomentosum is thought to be pollinated by moths (Order: Lepidoptera) while other Gossypium species are pollinated by bees (Order: Hymenoptera). The flowers are also different to those of the other Gossypium species as they stay open at night whereas most Gossypium flowers open in the morning and wither by the end of the same day.

(Animal and Plant Health inspection Service, USDA. 15 Apr. 2006.
http://www.aphis.usda.gov/brs/cotton.html.)

The Hawaiian name ma`o refers to the coloration of the flowers and can be translated as "yellow green". The alternative name huli huli translates as "hairy" in reference to the hairs present on the surface of the leaves. The genus name Gossypium comes from the Greek word for cotton - "gossypion". The specific epithet tomentose means woolly in reference to the long fibers present on the seeds.

(DeJoode, D. R. and J. F. Wendel. 1992. Genetic diversity and origin of the Hawaiian Islands cotton, Gossypium tomentosum. American Journal of Botany. 79(11): 1311-1319.)
(Plowden, C. C., 1970. A Manual of Plant Names, Philosophical Library, New York.)

Gossypium tomentosum is an endemic shrub that was previously considered vulnerable by the International Union for the Conservation of Nature and Natural Resources but is not currently listed on the IUCN Red List.

IUCN. 2004 IUCN Red List of Threatened Species. . 15 Apr. 2006.

The short, brown seed fibers of the Hawaiian cotton species, Gossypium tomentosum, are not utilized for the production of fiber. This species has however been utilized in cotton breeding programs for the production of flowers lacking nectaries in an effort to reduce insect damage within cotton crops. Current research also involves crosses of G. tomentosum with other cotton species for investigation of the potential beneficial effects on fiber yield and quality, plant stature, pest resistance, and heat and drought stress tolerance.

(DeJoode, D. R. and J. F. Wendel. 1992. Genetic diversity and origin of the Hawaiian Islands cotton, Gossypium tomentosum. American Journal of Botany. 79(11): 1311-1319.)

We currently have 26 herbarium specimens for Gossypium tomentosum in our collection. Click on any specimen below to view the herbarium sheet data.

• 047603 - collected by V. J. Krajina in 1961
• 044615 - collected by Steven P. Darwin in 1975
• 015159 - collected by Joel Lau in 1985
• 036558 - collected by Wayne Takeuchi in 1986
• 013295 - collected by K. R. Wood in 1992
• 013644 - collected by Steve Perlman in 1992
• 013294 - collected by K. R. Wood in 1992
• S047695 - collected by Steve Perlman in 1992
• 022536 - collected by Steve Perlman in 1996
• 022578 - collected by Steve Perlman in 1998
• 069808 - collected by K. R. Wood in 2004
• 043018 - collected by Natalia Tangalin in 2004
• 043018 - collected by Natalia Tangalin in 2004
• 042455 - collected by Hank Oppenheimer in 2004
• S004116 - collected by Hank Oppenheimer in 2004
• 056328 - collected by Natalia Tangalin in 2004
• S062257 - collected by Natalia Tangalin in 2004
• 049797 - collected by Hank Oppenheimer in 2006
• 064496 - collected by K. R. Wood in 2009
• S064724 - collected by K. R. Wood in 2009
• 061998 - collected by Alex Lehman in 2011
• 065911 - collected by Natalia Tangalin in 2012
• 081982 - collected by Seana Walsh in 2020
• Unassigned - collected by Seana Walsh in 2020
• Unassigned - collected by Dustin Wolkis in 2024
• Unassigned - collected by Dustin Wolkis in 2024