Kauai scientists recently rediscovered a relative of the hibiscus, once believed to be extinct 10 years ago, along the remote vertical cliffside of Kalalau Valley on Kauai.

National Tropical Botanical Garden researchers flew a drone to survey Kalalau Valley for rare and endangered plants. Scientists came across a small colony of native plant Hibiscadelphus woodii, which was reportedly last seen alive on Kauai in 2009.

Native honeycreeper birds and ‘amakihi likely pollinate the nectar-rich, bright yellow flowers that turn purple-maroon with age.

Hibiscadelphus woodii is listed on the IUCN Red List of Threatened Species as an extinct relative of the hibiscus. The flower faces threats from rock slides, invasive plants and animals such as goats and feral pigs.

In 1991, NTBG botanists first discovered the plant growing on a sheer cliff in the Kalalau Valley. The new species was officially given a scientific name, which was published in 1995.

During the late 1990s, falling boulders severely crushed the plant’s colony and led to its presumed extinction.

Researchers made many failed attempts to propagate or reproduce the flower. They tried cross-pollinating, grafting and using tip cuttings to no avail.

The recent rediscovery of the flower using drone technology was funded by a grant from the Mohamed bin Zayed Species Conservation Fund.

The nonprofit organization NTBG conducts field surveys and works to save plants facing extinction.

“Drones are unlocking a treasure trove of unexplored cliff habitat, and while this may be the first discovery of its kind, I am sure it won’t be the last,” said Ben Nyberg, NTBG’s drone specialist, in a statement.