Melicope lydgatei
Overview
Melicope lydgatei is a critically endangered shrub or small tree endemic to the Hawaiian Islands, representing one of the rarest members of the citrus family (Rutaceae) in the Pacific. This distinctive plant typically grows 2-4 meters tall with compound leaves arranged in groups of three leaflets, each displaying a glossy dark green surface with prominent veining. The species produces small, inconspicuous white to pale yellow flowers in terminal clusters, followed by small capsular fruits that split to reveal shiny black seeds.
Historically found in mesic to wet forests on volcanic slopes, Melicope lydgatei occupies native Hawaiian forest ecosystems between 300-1,200 meters elevation, where it grows alongside other endemic Hawaiian flora including koa, ohia, and native ferns. The species is classified as Critically Endangered by the IUCN, with its population experiencing a severe decline over recent decades. Current estimates suggest fewer than 50 mature individuals remain in the wild, scattered across highly fragmented forest patches on the Big Island and possibly Maui.
The primary threats include habitat destruction from feral ungulates, competition from invasive plant species, and the cascading effects of ecosystem degradation. However, recent conservation efforts have shown promise, with several botanical gardens successfully propagating the species from seed and cuttings. The Lyon Arboretum and other Hawaiian conservation organizations have established ex-situ collections, providing crucial genetic backup populations.
Additionally, habitat restoration projects in native forest areas are creating suitable conditions for potential reintroduction efforts, offering hope for this remarkable endemic species.
Melicope lydgatei faces severe pressure from feral pigs and goats that trample seedlings and destroy understory habitat essential for regeneration. Aggressive invasive plants, particularly strawberry guava and Miconia calvescens, outcompete the species for light and nutrients in its native forest habitat. Climate change compounds these threats by altering precipitation patterns in the mesic forests where remaining populations persist, while also facilitating the spread of invasive species into higher elevation refugia.
Habitat
This species inhabits mesic to wet native Hawaiian forests on volcanic slopes, typically growing in the understory or forest edges at elevations between 300-1,200 meters. It thrives in well-drained volcanic soils with consistent moisture and partial shade provided by the native forest canopy.