[3] This ecoregion includes one of the world's wettest places, the slopes of Mount Waiʻaleʻale, which average 373 in (9,500 mm) of rainfall per year.

These forests have been dominated by the native hala (Pandanus tectorius) and hau (Hibiscus tiliaceus) and naturalized (Polynesian introductions) kukui (Aleurites moluccana) and milo (Thespesia populnea) for the past 1,000–2,000 years.

[6] Mixed mesic forests, at 750 to 1,250 m (2,460 to 4,100 ft) on the windward slopes of the large islands in addition to the summit of Mount Lānaʻihale on Lānaʻi, receive 1,000 to 2,500 mm (39 to 98 in) of rainfall annually and thus may not be true rainforests.

[7] Other trees and shrubs include pāpala (Charpentiera obovata), olopua (Nestegis sandwicensis), hame (Antidesma platyphyllum), mēhame (A. pulvinatum), kōpiko (Psychotria mariniana), ʻōpiko (P. mauiensis), ʻiliahi (Santalum freycinetianum), hōlei (Ochrosia spp.

), poʻolā (Claoxylon sandwicense), kōlea lau nui (Myrsine lessertiana), kauila (Alphitonia ponderosa), nioi (Eugenia reinwardtiana), aʻiaʻi (Paratrophis pendulina), and hōʻawa (Pittosporum spp.).

Other trees include kāwaʻu (Ilex anomala), ʻalani (Melicope clusiifolia), ʻōhiʻa ha (Syzygium sandwicensis), kōlea lau nui (Myrsine lessertiana), ʻohe (Tetraplasandra spp.

), kāmakahala (Geniostoma hirtellum), kanawao (Broussaisia arguta), Phyllostegia spp., ʻākala (Rubus hawaiensis), kāmanamana (Adenostemma lavenia), Pilea peploides, māmaki (Pipturus albidus), olonā (Touchardia latifolia), and ʻalaʻala wai nui (Peperomia spp.)

(Freycinetia arborea), puaʻakuhinia (Astelia menziesiana) and ʻōlapa (Cheirodendron trigynum) are epiphytic flowering plants found in wet forests.

Epiphytic ferns, such as Adenophorus spp., ohiaku (Hymenophyllum recurvum), Ophioglossum pendulum, ʻākaha (Asplenium nidus), ʻēkaha (Elaphoglossum hirtum), and makue lau lii (Grammitis hookeri), cover trees.