Northwestern Pacific

Northwestern Pacific groups Micronesia and Japan's southern offshore islands into a single botanical region. It covers Palau, the Federated States of Micronesia (Yap, Chuuk, Pohnpei, Kosrae), the Marianas — both Guam and the Northern Marianas — the Marshall Islands, and the Bonin and Volcano islands far south of Tokyo. Climates run mostly tropical (Köppen Af and Am), with rainforest on windward slopes and drier conditions on leeward coasts. The Bonin Islands drift into subtropical territory.

Land area is small — well under three thousand square kilometres scattered across an ocean basin — but the topography is varied. High volcanic islands like Pohnpei, Kosrae, Palau, and the Northern Marianas rise from sea level to nearly a thousand metres at Mt. Agrihan, while the Marshall and Caroline atolls sit only a few metres above the waves. This contrast supports a wide range of habitats: lowland rainforest, montane cloud forest on Pohnpei and Kosrae, coral atoll vegetation, mangroves, and the distinct Bonin shrubland.

The flora reflects long oceanic isolation. The Bonin Islands — Ogasawara in Japanese — hold so many endemic species that they are sometimes called the Galápagos of the Orient, and UNESCO lists them as a natural World Heritage site for that reason. Palau and Pohnpei are similarly diverse, with endemic palms such as Clinostigma carolinense and the cycad Cycas micronesica anchoring island-specific plant communities. Characteristic families across the region include Pandanaceae, Cycadaceae, Rubiaceae, and the widespread Pacific genera Ficus and Hibiscus.

A handful of broadly distributed species in this region appear in the Verdarium catalogue — the bird's nest fern (Asplenium nidus), the trailing fig (Ficus sagittata), the dragon tail plant (Epipremnum pinnatum), and the sundew Drosera spatulata. These are Indo-Pacific generalists rather than true Micronesian endemics. The region's narrowly distributed species, particularly Bonin endemics and Pohnpei palms, tend to be rare in cultivation and absent from typical houseplant supply.