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Tropical & Subtropical Grasslands, Savannas & Shrublands

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Northwest Hawai'i scrub

Biome

Tropical & Subtropical Grasslands, Savannas & Shrublands

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Biogeographic realm

Oceania

Laysan Island interior with low scrub vegetation, sand, lagoon edge, and nesting seabirds.

Region photo - Cindy Rehkemper/USFWS / Wikimedia Commons - Public domain.

Northwest Hawai'i scrub

The Northwest Hawai'i scrub ecoregion spans the remote Northwestern Hawaiian Islands, a chain of low atolls and islets in the Oceanian realm stretching roughly 1,350 to 1,600 kilometers from rocky Nihoa in the southeast to low Kure Atoll, all within the U.S. state of Hawaii. Set on the eroded remnants of ancient volcanic islands and coral sand, the vegetation is treeless tropical shrubland: banks of low, salt-tolerant shrubs and ground plants fringing lagoons, with common species including Portulaca lutea and Boerhavia repens. Conditions are harsh, with storms, flash floods, and tsunamis shaping this tropical island habitat. The ecoregion harbors several endangered endemic plants, among them the Nīhoa fan palm (Pritchardia remota), Schiedea verticillata, and Amaranthus brownii, alongside the endangered Hawaiian monk seal and endemic birds such as the Laysan duck, Laysan finch, and Nīhoa finch; collectively the islands form the largest tropical seabird rookery in the world and lie entirely within the protected Papahānaumokuākea Marine National Monument. For gardeners, the native fan palm genus Pritchardia represents the region's most horticulturally notable group, the same palms that once formed forests on Nihoa.

RESOLVE 641

Oceania

6 sq mi

Tropical & Subtropical Grasslands, Savannas & Shrublands

Landscape type

Tropical & Subtropical Grasslands, Savannas & Shrublands

Plant region

Oceania

Region footprint

6 sq mi

Habitat pressure

Nature Imperiled (Dinerstein NNH 4)

Source & care

Plants that can handle this region

Plotwright does not have climate-fit plant matches for this region yet. As the catalog grows into this climate band, suggestions will appear here.

Similar planting regions

Browse other regions in the same biome. Their plant lists can suggest species and combinations worth comparing.

Subalpine shrubland on the upper slopes of Haleakala, Maui, with the island below.

RESOLVE 639 - Oceania

Hawai'i tropical high shrublands

The Hawaiʻi tropical high shrublands occupy the upper slopes of four great volcanoes in the US state of Hawaii: Mauna Kea, Mauna Loa, and Hualālai on Hawaiʻi Island, and Haleakalā on Maui. Above the forest line, alpine deserts and grasslands give way downslope to subalpine shrublands, where hardy, cold- and drought-adapted plants dominate, including ʻāheahea (Chenopodium oahuense), ʻōhelo ʻai (Vaccinium reticulatum), naʻenaʻe and related Dubautia shrubs, and ʻiliahi sandalwood (Santalum haleakalae), alongside tussock grasses such as Deschampsia nubigena. This is a high-elevation subtropical highland climate marked by dry, cold conditions on the exposed summits. Its signature plant is the Hawaiian silversword, ʻāhinahina (Argyroxiphium sandwicense), part of an endemic alliance descended from a North American tarweed, while the nēnē goose and ʻuaʻu (Hawaiian petrel) are among its native fauna. The ecoregion is considered vulnerable, pressured by grazing and trampling from feral livestock and by invasive species. For mountain or rock gardeners, the native ʻōhelo (Vaccinium reticulatum), a low cranberry relative, is a notable cold-hardy ornamental from this flora.

Tropical & Subtropical Grasslands, Savannas & Shrublands

RESOLVE 640 - Oceania

Hawai'i tropical low shrublands

The Hawai'i tropical low shrublands occupy the dry, leeward lowlands of the main Hawaiian Islands, blanketing the lowest slopes of the larger islands and nearly all of the smaller ones such as Lāna'i, Kaho'olawe, and Ni'ihau (the Northwestern Hawaiian Islands form a separate ecoregion). The vegetation is a mix of native grasslands and coastal shrublands carpeted in low-growing plants, dominated by 'ilima (Sida fallax), 'a'ali'i (Dodonaea viscosa), naupaka (Scaevola), pūkiawe (Styphelia tameiameiae), and the grass kāwelu (Eragrostis variabilis). This is the driest of all lowland habitats in the archipelago, with rainfall concentrated in the winter months, giving it a tropical-savanna character. More than 90 percent of its plant species are found nowhere else, including the flagship 'ōhai (Sesbania tomentosa), and the small flowers are pollinated by native Hawaiian yellow-faced bees; today the ecoregion is rated critically endangered, with little intact habitat left after losses to development, fire, feral animals, and invasive species. For drought-tolerant native plantings, the shrubland's own 'ilima, naupaka, and 'a'ali'i are well-suited ornamental choices.

Tropical & Subtropical Grasslands, Savannas & Shrublands

RESOLVE 34 - Afrotropic

Angolan mopane woodlands

The Angolan mopane woodlands stretch across southwestern Angola and northern Namibia, running along the Owambo Basin and surrounding the salt flats of the Etosha Pan. As the name suggests, the ecoregion is dominated by the mopane tree (Colophospermum mopane), which grows as a single-stemmed tree up to about 10 meters tall or, where conditions are harsher, as a dense shrub, alongside associated Acacia, Combretum, and Commiphora species. The climate is dry, with rainfall concentrated in the summer and peaking in late summer. The woodlands shelter elephants, black and white rhinoceros, lion, and cheetah, as well as the near-endemic black-faced impala, and the wider region is anchored by protected areas including Namibia's Etosha National Park. Mopane here also has a direct human use, as the caterpillars of the mopane emperor moth are gathered locally as food.

Tropical & Subtropical Grasslands, Savannas & Shrublands

RESOLVE 35 - Afrotropic

Angolan scarp savanna and woodlands

The Angolan scarp savanna and woodlands form a long, narrow strip along the coast of Angola, running from the Atlantic shore up the steep west-facing escarpment that climbs roughly 1,000 meters to the country's central plateau. Vegetation shifts dramatically with elevation, grading from dry woodland and wooded grassland-where baobab, Strychnos, and Acacia welwitschii grow-up to humid mist and cloud forests whose canopy includes Khaya anthotheca, Bombax buonopozense, and Spathodea campanulata. The climate is tropical with summer rains; the coastal belt, cooled by the Benguela Current, stays humid but receives relatively little rain, while the escarpment is far wetter. Despite being poorly studied and only partly protected within reserves such as Quiçãma National Park, the region is rich in endemics, including the red-crested turaco and the grey-striped francolin, and is classified as Vulnerable. For gardeners, the showy African tulip tree (Spathodea campanulata), grown as an ornamental in warm climates worldwide, is native to these escarpment forests.

Tropical & Subtropical Grasslands, Savannas & Shrublands

RESOLVE 36 - Afrotropic

Angolan wet miombo woodlands

The Angolan wet miombo woodlands blanket most of the central Angolan plateau and extend north into the Democratic Republic of the Congo, sitting largely at elevations between about 1,000 and 1,500 meters. The defining habitat is miombo woodland, a moist deciduous broadleaf savanna dominated by legume trees of the family Fabaceae (subfamily Caesalpinioideae), especially the genera Brachystegia, Julbernardia, and Isoberlinia, with grassland and sandy-soil openings between the stands. The climate is tropical and notably wetter than the surrounding savanna, with rainfall strongly concentrated in the hot summer months from roughly November to March. The ecoregion is the stronghold of the giant sable antelope (Hippotragus niger variani), a critically endangered Angolan endemic protected at Cangandala National Park, and it also harbors a strict-endemic rodent, Vernay's climbing mouse. For gardeners, the signature native flora here are the canopy-forming Brachystegia and Isoberlinia legume trees that give the miombo its character.

Tropical & Subtropical Grasslands, Savannas & Shrublands

RESOLVE 181 - Australasia

Arnhem Land tropical savanna

The Arnhem Land tropical savanna covers the rugged Arnhem Land peninsula and its offshore islands, including the Tiwi Islands, Groote Eylandt, and the Wessel Islands, in Australia's Northern Territory. Eucalypt open forests dominate the landscape, led by Darwin stringybark (Eucalyptus tetrodonta) and Darwin woollybutt (Eucalyptus miniata) over a tall understory of Sorghum grasses, interspersed with monsoon rainforest patches, mangroves, and Melaleuca swamp forests. The climate is tropical and strongly monsoonal, with a summer wet season and a largely rainless dry season. Long isolation has made it exceptionally diverse: over 1,900 plant taxa have been recorded, at least 200 of them found nowhere else, and a 2017 assessment found that 36% of the ecoregion lies within protected areas such as Kakadu National Park.

Tropical & Subtropical Grasslands, Savannas & Shrublands

Educator packet

Region packet

Northwest Hawai'i scrub educator packet

The Northwest Hawai'i scrub ecoregion spans the remote Northwestern Hawaiian Islands, a chain of low atolls and islets in the Oceanian realm stretching roughly 1,350 to 1,600 kilometers from rocky Nihoa in the southeast to low Kure Atoll, all within the U.S. state of Hawaii. Set on the eroded remnants of ancient volcanic islands and coral sand, the vegetation is treeless tropical shrubland: banks of low, salt-tolerant shrubs and ground plants fringing lagoons, with common species including Portulaca lutea and Boerhavia repens. Conditions are harsh, with storms, flash floods, and tsunamis shaping this tropical island habitat. The ecoregion harbors several endangered endemic plants, among them the Nīhoa fan palm (Pritchardia remota), Schiedea verticillata, and Amaranthus brownii, alongside the endangered Hawaiian monk seal and endemic birds such as the Laysan duck, Laysan finch, and Nīhoa finch; collectively the islands form the largest tropical seabird rookery in the world and lie entirely within the protected Papahānaumokuākea Marine National Monument. For gardeners, the native fan palm genus Pritchardia represents the region's most horticulturally notable group, the same palms that once formed forests on Nihoa.

Realm

Oceania

Dominant biome

Tropical & Subtropical Grasslands, Savannas & Shrublands

Approximate area

6 square miles

States / provinces

Not recorded

Climate descriptor

Not recorded

Classroom prompts

- Which climate and biome facts explain why this region supports its characteristic plants?

- How do native-plant and wildlife-support claims differ from a species-presence claim?

- Which source-backed facts would you cite before using this region in a classroom map activity?

Use the Sources & citations section below for page citation styles and region source links.

Sources & citations

Cite this page

For lesson plans, articles, or regional planting notes that use this Plotwright page. To cite the underlying ecoregion framework or a specific editorial profile, use the source cards below.

Plotwright. (n.d.). Northwest Hawai'i scrub (Northwest Hawai'i scrub). Retrieved 2026, August 20, from https://plotwright.com/regions/resolve-641

Sources for this region

This page cites Plotwright first for the compiled view, then lists the upstream framework, climate, and editorial source pages so readers can cite the original material directly.

RESOLVE 2017 Terrestrial Ecoregions (Dinerstein et al.)

Primary ecoregion framework

One Earth

Wikipedia

Wikimedia Foundation

Open source

Source guide