Emergency gardening: labs step in to help conserve the rarest plants on earth - csy

Science News, August 9, 2003 by Susan Milius

Soon after Murch got her lab set up in February, she started with the direst cases, such as the hard-luck shrub called Kanaloa kahoolawensis. The last part of its name comes from the Hawaiian island Kaho'olawe, which is 13 miles long and, at its widest, 8 miles across. Goats and other animals introduced by Europeans flourished there, destroying native vegetation, and the U.S. Army and Navy used the island for target practice between 1941 and 1990.

Botanists Ken Wood and Steve Perlman of the National Tropical Botanical Garden were exploring the island in the early 1990s when they discovered two unusual sprawling shrubs on a tall rock just offshore. The shrubs' flowers, in tufts like a mimosa's but the color of cream, bloomed over blunt oval leaves.

Wood and his colleague taxonomist David Lorence had never seen the plant before, but they consulted a specialist who knew the pollen well. The relatively smooth grains with grooves, typical for a legume, had been turning up in samples of ancient soils all over the islands. Paleontologists had concluded that the mysterious plant releasing this pollen must once have dominated the lowland landscape.

The researchers published the official description of the plant in 1994, declaring it unusual enough not just to be designated as a new species but to have its own new genus. Lorence assigned a generic name that honors the Hawaiian god Kanaloa.

The plants seem to be "mostly male," as Lorence puts it: most of the blooms grow only male parts. But one year, biolofgists found three seeds from one of the plants. That happy fluke has yielded two shrubs that now sit in a place of honor at the entrance to the botanic garden's rare-plant nursery.

Unfortunately, that burst of luck faded. Horticulturists at the facility have repeatedly failed to propagate the plant by cuttings or grafts. "The greenhouse staff is very excellent," says Murch. Their record glows with innovations in coaxing little-studied species into reproducing, so if they didn't manage, Murch deems the prospects grim.

Waiting for more seeds began to seem unpromising, too. Drought hit Kaho'olawe so hard that in 2001, island managers sent helicopter expeditions out to water the plants. "The helicopter puts one skid down on a boulder about half the size of your desk and you get out--carefully," recalls island restoration manager Paul Higashino. Then the helicopter went back to pick up 400 pounds of 5-gallon water containers. Keeping an eye out for unexploded ordnance on the rocky slope, the emergency-watering crew directed the container drop.

Even with three waterings, one of the plants withered to what a casual observer, or less of a diehard optimist than Higashino, might call dead. "I don't want to say that on my watch one died," he says.

When Murch arrived in Kauai, she approached the problem by observing the two Kanaloa plants growing near her lab's front door. From these--by then, two-thirds of the world's K. kahoolawensis population--Murch noted details of the leaf-bud structure and other clues to what sort of hormones and nutrients might work. Unfortunately, there were parts of the plants that she couldn't study, such as the root system.