Metrosideros polymorpha, or ʻōhiʻa lehua (sometimes simply the lehua tree or ʻōhiʻa), is the most abundant native tree species on the six largest Hawaiian islands.
However, on Hawai’i island (the Big Island), the species is under attack by the fungus Ceratocystis fimbriata. As noted on the linked page, seemingly healthy trees die within the span of a few days to a few weeks, so the fungal pathogen is better known as ROD or Rapid ʻŌhiʻa Death. The pathogen is not yet known to have reached the other islands, but one suspects it is only a matter of time. Of note to any fungal taxonomists reading this entry, Ceratocystis fimbriata may prove to be an unresolved species complex, as different “strains” of the fungus individually affect a myriad of tropical plants and economic crops.
In the species’ favour,
Forms of Metrosideros polymorpha are found in almost all Hawaiian ecosystems ranging from lowland dry shrub lands to rain forests, from high elevation bogs to dry lava flows.
…[it]is an extremely variable plant. It ranges in habit from a prostrate shrub to a 30 m tall tree.
Presumably (and the research would need to be done to confirm, if it hasn’t already), the constant re-establishment of seedlings on newly-formed lava beds would prevent the species from becoming extinct from the fungal pathogen. Still, Metrosideros polymorpha is a major constituent of the flora of Hawai’i. A number of native fauna species rely upon its presence and abundance, such as the critically-endangered Hawaiian honeycreeper ʻakekeʻe. Significant changes in the number of ʻōhiʻa lehua trees in specific areas (like high-elevation forests required by ʻakekeʻe) could be the death knell for such endangered species. Fortunately for ʻakekeʻe conservation, the pathogen is not yet found on Kauai.
Metrosideros polymorpha is a culturally important plant to Hawaiian peoples. In the sacred high elevation forests, this species in particular is considered the home of two creation gods. Another association is with love, for both nature and family. Flowers of Metrosideros polymorpha are thusly made into leis (especially on the Big Island) for a number of symbolic reasons. Read The cultural significance of ʻōhiʻa lehua from Hawai’i Magazine for more.
Unsurprisingly, the species also makes its way into Hawaiian Proverbs & Poetical Sayings (sayings and definitions from this exceptional book):
He kumu lehua muimuia i ka manu
…translates to “a lehua tree covered with birds”, meaning an attractive person (a lehua tree in bloom attracts birds as an attractive person draws the attention of others).
He lāʻau ku hoʻokāhi, he lehua no Kaʻala
…translates to “a lone tree, a lehua of Kaʻala”, meaning an expression of admiration for an outstanding person, unequaled in beauty, wisdom, or skill.