Hawaiian Montane Rainforest

These forests occur in the high rainfall areas of most of the main islands reaching elevations in excess of 1600 m. Like the dry forests, they are often dominated by the ubiquitous endemic Metrosideros polymorpha (Myrtaceae) and can have canopy heights up to 20 m. The great variation seen in Metrosideros polymorpha with foliage colour varying from dark, greenish, grey to bright green and flowers that vary in colour from crimson to light coral red have led to the recognition of a number of varieties. Other characteristic trees include a variety of endemics such as Antidesma platyphyllum (Euphorbiaceae), Bobea timonioides, Hedyotis terminalis, Psychotria hawaiiensis (Rubiaceae), Pisonia sandwicensis (Nyctaginaceae) and Tetraplasandra hawaiensis (Araliaceae). In the relatively undisturbed stands most of the under storey species are also endemic. Typical endemic shrubs include Cyrtandra platyphylla (Gesneraceae), Dubautia scabra (Asteraceae), Hedyotis hillebrandii (Rubiaceae), Lysimachia hillebrandii (Primulaceae), Myrsine sandwicensis (Myrsinaceae) and Vaccinium dentatum (Ericaceae). These forests are also rich in tree ferns with species such as the endemic Cibotium hawaiiense (Dicksoniaceae) together with tall growing ferns of the endemic genus Sadleria such as S. cyatheoides and S. pallida (Blechnaceae).  The many smaller endemic ferns include Athyrium microphyllum (Athyriaceae) and Ctenitis rubiginosa (Dryopteridaceae).  Among the vines, several endemic species of the Lamiaceae are relatively common including Phyllostegia vestita and Stenogyne rugosa, as is the endemic epiphytic shrub Clermontia clermontioides (Campanulaceae), while the rich epiphytic herbaceous flora includes the endemic Astelia menziesiana (Liliaceae) and a multitude of filmy ferns.

Hawaiian Dry Montane Forest

Lowland dry forest in which the endemic Metrosideros polymorpha (Myrtaceae) is usually present, but only predominating on Hawai’i, occurs on all of the main islands up to an altitude of about 1500 m. However, they tend to be confined to the dryer rain shadow areas. The canopy height varies from 4 to 20 m, and apart from the summer deciduous endemic species Erythrina sandwichensis (Fabaceae), Euphorbia haeleeleana (Euphorbiaceae) and Reynoldsia sandwicensis (Araliaceae) all of the woody plants are evergreen. The diversity of these forests seem to be correlated with island age with the best examples on the geologically older Kaua’I and O’ahu, while the examples on Hawai’i are relatively impoverished. Other important canopy trees include the endemic Colubrina oppositifolia (Rhamnaceae), Diospyros sandwicensis (Ebenaceae) and Nestegis sandwicensis (Oleaceae), any one of which may dominate depending on the area. Today only a few relict stands remain of this once extensive forest system, and in these can be found many other of the BioProvinces remaining endemic trees such as Alphitonia ponderosa (Rhamnaceae), Antidesma pulvinatum (Euphorbiaceae), Bobea sandwicensis (Rubiaceae), Charpentiera obovata (Amaranthaceae), Gardenia brighamii (Rubiaceae), Kokia drynarioides (Malvaceae), Myrsine lanaiensis (Myrsinaceae), Nothocestrum brevifolium (Solanaceae), Pittosporum hosmeri (Pittosporaceae), Pleomele aurea (Agavaceae), Pouteria sandwicensis (Sapindaceae), Rauvalvia sandwicense (Apocynaceae), Santalum ellipticum (Santalaceae), Sapindus oahuensis (Sapindaceae), Xylosma hawaiiense (Flacourtiaceae) and Zanthoxylum dipetalum (Rutaceae). In some cases these forests are somewhat open with a grassy ground layer, but where there is a closed canopy a diverse assemblage of under storey species can be found including many endemic shrubs like Delissea rhytidosperma (Campanulaceae) and Gossypium tomentosum (Malvaceae). Epiphytes, on the other hand, are scare, but there are a few endemic lianas such as Alyxia oliviformis (Apocynaceae) and Bonamia menziesii (Convolvulaceae). 

Hawaiian Acacia koa Montane Forest

Forests dominated by the endemic Acacia koa (Fabaceae) extend from an altitude of about 300 m in the warm lowlands to about 2,300 m where cool sub alpine conditions prevail. They tend to be confined to leeward and windward slopes where conditions are slightly dryer. Acacia koa belongs to a largely Australian group of acacias whose functional leaves are actually flattened leaf stems or phyllodes. Young trees have the typical feathery leaves of acacias but these drop off and are replaced by phyllodes as the tree grows. Of considerable phytogeographical interest is the fact that the closest living relative of Acacia koa is A. heterophylla found on Reunion Island in the Indian Ocean. Other trees commonly associated with Acacia koa include a considerable number of endemic species such as Bobea elatior, Psychotria mariniana (Rubiaceae), Diospyros hillebrandii (Ebenaceae), Elaeocarpus bifidus (Elaeocarpaceae), Gardenia remyi (Rubiaceae), Myrsine kauaiensis (Myrsinaceae), Psydrax odoratum (Rubiaceae), Santalum freycinetianum (Santalaceae) and Syzygium sandwicensis (Myrtaceae). The shrub layer comprises species such as the endemic Boehmeria grandis, Pipturus albidus (Urticaceae), Broussaisia arguta (Hydrangeaceae), Cyanea angustifolia, Rollandia lanceolata (Campanulaceae), Phyllanthes distichus (Euphorbiaceae), Scaevola gaudichaudiana (Goodeniaceae) and Wikstroemia oahuensis (Thymelaeaceae). The ground vegetation, on the other hand, is usually fairly sparse with virtually no bryophytes. The few vascular plants include Oplismenus hirtellus, Paspalm orbiculare and the endemic Carex wahuensis (Cyperaceae). There also seem to be few epiphytic or climbing species, but these may include, for example, the primitive Psilotum nudum, the endemic climber Canavalia galeata (Fabaceae) and the endemic, epiphytic shrub Clermontia kakeana (Campanulaceae).

Hawaiian Montane Cloud Forest

Shrouded in fog on a regular basis, these forests form a belt stretching from an altitude of about 1000 m to the upper cloud limit set by the trade wind inversion at about 1900 m, and are typically composed of gnarled and stunted trees enveloped in mosses and lichens. They are characterized by the presence of lots of shade-adapted plants (sciophytes), and in this BioProvince by the lack of the heliophytic fern Dicranopteris linearis.  Like so many of the Hawaiian forests the endemic Metrosideros polymorpha (Myrtaceae) is one of the major canopy trees, while other important trees include the endemic Acacia koa (Fabaceae), Cheirodendron faurii, C. trigynum (Araliaceae), Hedyotis terminalis (Rubiaceae) and Myrsine lesstiana (Myrsinaceae), but the actual composition varies for island to island. There is also good representation of endemic species of Coprosma (Rubiaceae) and Pelea (Rutaceae) including C. elliptica, C. kauensis, C. ochracea, C. pubens, C. rhynchocarpa, C. waimeae, P. christophersenii, P. clusiifolia, P. cruciata, P. feddei, P. haleakalae, P. oahuensis, P. orbicularis and P. volcanica, but again the composition varies from island to island. Tree ferns are also conspicuous with species like Cibotium glaucum and C. chamissoi, while other interesting elements include the endemic palm-like trees Cyanea tritomanth (Campanulaceae) and the endemic giant dock Rumex giganteus (Polygonaceae).  The shrub layer is also very rich in species with about three times as many as in the dry forests. These include endemics like Cyrtandra paludosa (Gesneraceae), Touchardia latifolia, Urera glabra (Urticaceae) and Vaccinium calycinum (Ericaceae).  The ground cover is composed largely of native ferns such as Dryopteris wallichiana, while the scattering of flowering plants includes endemics like Carex alligata (Cyperaceae), Luzula hawaiiense (Juncaceae) and Phyllostegia macrophylla (Lamiaceae). Vines and climbers include the endemic Stenogyne calaminthoides (Lamiaceae) and Vicia menziesii (Fabaceae), and there are several endemic lianas like Embelia pacifica (Myrsinaceae), Labordia hedyosmifolia (Loganiaceae) and Smilax melastomifolia (Smilacaceae).


Campbell, D. H. 1933. The flora of the Hawaiian Islands. Quarterly Review of Biology, 8: 164-184.

Campbell, D. G. & Hammond, H. D. 1989. Floristic Inventory of Tropical Countries. The New York Botanical Garden.

Carlquist, S. 1970. Hawaii A Natural History. The American Museum of Natural History.

Fosberg, F. R. 1984. Phytogeographic comparison of Polynesia and Micronesia. In: Biogeography of the Tropical Pacific (Proceedings of a Symposium). Eds. F. J. Radovsky, P. H. Raven and H. Sohmer. Bishop Museum Special Publication No. 72.

Kitayama, K. & Mueller-Dombois. 1992. Vegetation of the wet windward slopes of Haleakala, Maui, Hawaii. Pacific Science, 46: 197-220.

Leith, H. & Werger, M. J. A. 1989. Ecosystems of the World 14B - Tropical Rain Forests. Elsevier Scientific Publishing Company.

Loope, L. L., Hamann, O. & Stone, C. P. 1988. Comparative conservation biology of oceanic archipelagoes - Hawaii and the Galapagos. Bioscience, 38: 272-282.

MacCaughey, V. 1917. Vegetation of Hawaiian lava flows. Botanical Gazette, 64: 386-420.

Medeiros, A. C., Loope, L. L. & Hobdy, R. W. 1995. Conservation of cloud forest in Maui County (Maui, Molokai, and Lanai) Hawaiian Islands. In: Tropical Montane Cloud Forests. Eds.  L. S. Hamilton, J. O. Juvik and F. N. Scatena. Ecological Studies 10. Springer-Varlag.

Mueller-Dombois, D. 2000. Succession and zonation of the vegetation in the volcanic mountains of the Hawaiian Islands. Acta Phytogeographica Suecica, 85: 31-40.

Mueller-Dombois, D. & Fosberg, F. R. 1998. Vegetation of the Tropical Pacific Islands. Springer.

Pau, S., Gillespie, T. W. & Price, J. P. 2009. Natural history, biogeography, and endangerment of Hawaiian dry forest trees. Biodiversity and Conservation, 18: 3167-3182.

Ricketts, T. h. et al. 1999. Terrestrial Ecosystems of North America - a conservation assessment. World Wildlife Fund, USA and Canada. Island Press, Washington.

Schmid, M. 1989. The forests in the tropical Pacific archipelagoes. In: Ecosystems of the World 14B - Tropical Rain Forest Ecosystems.  Elsevier.

Sohmer, S. H. 1990. Elements of Pacific phytodiversity. In: The Plant Diversity of Malesia. Proceedings of the Flora Malesiana Symposium commemorating Professor Dr. C. G. G. J. van Steenis Leiden, August 1989. Eds. P. Baas, K. Kalkman and R. Geesink. Kluwer Academic Publishers.

Stone, B. C. 1967. A review of the endemic genera of Hawaiian plants. Botanical Review, 33: 219-259.

Wagner, W. L., Herbst, D. R. & Sohmer, S. H. 1999. Manual of the Flowering Plants of Hawai’i. Volumes 1 & 2. Bishop Museum Special Publication 97. Bishop Museum Press.