National Geographic

The remote, rugged cliff faces of Kalalau Valley on Kaua’i, Hawaii, are largely inaccessible to humans. For decades, researchers from the Kaua’i-based National Tropical Botanical Garden (NTBG) accessed these cliffs by hiking along treacherous ridgelines and rappelling down vertical cliff faces, scouring each nook and cranny for rare native plants. But now they have a new tool to help them: drones.

In late January, a drone flight made a startling discovery: Hibiscadelphus woodii, a relative of hibiscus last seen in 2009 and believed to be extinct, was still growing on the cliffside.

The species was first discovered in 1991, named in 1995, and deemed extinct in 2016. It has vibrant yellow flowers, which shift to a purplish hue over time. Researchers believe it is pollinated by native birds. While scientists had tried to use cross-pollination, grafting, and tip cuttings to propagate the plant, none of their attempts were successful.

Credit: National Tropical Botanical Garden

The January drone flight captured one image believed to be H. woodii, tucked into a corner. In February, they set out on another mission to reconfirm what they saw, flying a drone to the original GPS coordinates and collecting more images, revealing three individual H. woodii plants on the cliffside.

“We were hoping to catch it in flower, but it wasn’t flowering at that time,” says Ben Nyberg, drone specialist for NTBG. (See how drones are used for conservation.)..Read More at

National Geographic