A small plant with a tuft of yellow flowers is growing on a ridge on Kauai. The only noises are the wind and waves. The whine gets louder as a second drone is suspended from the first and cuts through the plant's stem. A member of the carnation family, the plant is lifted by the device. As the leaves flutter in the air, the drones descend and deliver it to the researchers.

This scene, repeated dozens of times with various plants on the Hawaiian island's tropical cliffsides as part of a new study, shows how drones can help scientists plucking rare and endangered plants from spots that would otherwise be difficult for humans to reach. It's important to collect samples to better understand the plight of these species. The use of technology to get more information than a person is wonderful. He is a board member of the National Tropical Botanical Garden, one of the institutions involved.

More than 250 native plant species can be found on Kauai, which is the subject of a recent study. Historically, botanists have rappelled down the island's sheer rock faces to reach specific plants, going to extreme lengths for samples that they can raise in a nursery to perpetuate species at risk of extinction. Ben wants to use remote-controlled flying robots in places that are hard to access.

The Mamba was built from scratch by the team using a commercially available drone. The researchers tried to figure out how the plant-picking arms could be made to reach out from the hovering drones. Guillaume Charron, an engineer from Outreach Robotics, is one of the study's authors. We came up with the idea of suspending a remote-controlled robotic arm on cables beneath a drones. The Mamba doesn't have to lift itself, so an operator can use its propellers to keep it stable.

The Mamba handing off a sample of Lysimachia iniki to team member Scott Heintzman. Credit: Ben Nyberg, National Tropical Botanical Garden

A hook that draws a plant's stem toward a blade is one of the components of the Mamba. The team is considering how to equip the Mamba with other tools, such as a vacuum that could suck in plant material or a nozzle that could spray seeds onto a cliff to replant.

The sky islands of the southwestern U.S. could be reached with similar drone systems. According to the study co-author, the drone system could be used in a variety of additional applications, such as tree canopy studies, depositing and data-collecting devices, or even planting trees. Users can reach completely inaccessible areas wherever they want.

The carnation species plucked from the high ridges of Kauai seems to be a new one. The seeds are being grown at the University of California, Irvine, thanks to the help of Ann and Steve Weller, a married couple who have studied the plant for more than 30 years. They have been able to map in detail the population in a way that we couldn't do by rappelling. I think it is a great new tool to know more about these plants.