Hau Kuahiwi (Hibiscadelphus woodii) is perched on the edge in more ways than one, following its rediscovery in 2019 using drone technology.
This small Hawaiian tree occurs only on the island of Kauai, where it lives on cliffs. Hibiscadelphus species are closely related to Hibiscus, but their distinctive curved flowers have an abundance of nectar and do not fully open, which is thought to be an adaptation to pollination by honeycreepers.
Predation and competition by non-native animals and plants drove the population to perilously low levels, and after three of the last four known individuals perished in a rockslide in the 1990s and the final plant died in 2011, the species was thought extinct. However, intensive drone surveys by National Tropical Botanical Garden in 2019 revealed a previously unknown population of another four individuals.
Significant challenges remain – the plants are completely unreachable by humans, and although this may afford them some protection from invasive species, rockslides remain a threat. It is possible that future technology could enable drones to collect plant material in the hope of establishing an ex situ population of this Hibiscadelphus and other similarly imperilled species for their long term protection.