The ʻohiʻa is Hawaii’s iconic tree, a keystone species that maintains healthy watersheds and provides habitat for numerous endangered birds. But a virulent fungal disease, possibly related to a warmer, drier climate, is now felling the island’s cherished `ohi`a forests.Hawaii’s isolation, 2,390 miles from the North American mainland, has given the island chain a unique array of species found nowhere else, including the ʻohiʻa lehua, an evergreen in the myrtle family with delicate pom-pom-shaped flowers composed of clusters of showy stamens in a range of hues from red and orange to pale yellow. In 2010, homeowners on the Big Island of Hawaii began reporting that ʻohiʻa in their upland rainforest were dying without apparent cause. Researchers named the mysterious condition “Rapid ʻOhiʻa Death” (ROD). On Google Earth, you can see the telltale brown streaks in the Puna forest reserve, Hawaii's largest remaining upland rainforest located on the slope of Kilauea volcano, where many ʻohiʻa lehua (Metrosideros polymorpha) trees have already succumbed. If you scroll over 60 miles to the west to the other side of the island, the green canopy behind Kealakekua Bay on the Kona coast — where Captain James Cook first set foot on Hawaii and was later killed — is pocked with the bleached skeletons of dead and dying trees. Scenes like these have become commonplace in the American West, where several conifer species, weakened by long-term drought and warmer temperatures, have been decimated by bark beetles. Researchers are wondering if climate change may also have stressed ʻohiʻa trees, perhaps helping to trigger the current outbreak on Hawaii. The fungus clogs the vascular system of the trees, making them wilt and die as if from a drought.An overall decrease in trade winds has created drier conditions in recent years in parts of the islands, at the same time that rising temperatures have warmed things up in the cool upland forests where ʻohiʻa thrive.