Hawai'i's Environment
Close call for rarest of plants
By Jan TenBruggencate
Advertiser Columnist
The rarest plant in the wild in Hawai'i may have gotten even rarer.
Two plants existed, both on Kaho'olawe, and one appears to have died.
The existence of the mysterious Kanaloa kahoolawensis was known only from some unidentified pollen found in prehistoric material on O'ahu until a decade ago.
In 1992, researchers Ken Wood and Steve Perlman of the National Tropical Botanical Garden found two scraggly shrubs they could not identify on a steep hillside on the Kaho'olawe coast.
They were identified as a new species, a member of the pea family, and named after the island on which they were located. Researchers later found the unidentified O'ahu pollen came from the same plant.
Pollen from the kanaloa also has been found on Kaua'i and Maui, and it is likely the plant was found throughout the Islands.
It was so common in pollen cores dating before the middle of the 1500s that it is believed to have been one of the dominant plants of the drylands, along with the now-rare fan palm, the loulu, and the 'a'ali'i, which has reddish leaves and winged seed pods.
Botanists suggest seed-eating rats, fire and agriculture were factors in the decline of kanaloa from one of Hawai'i's most common plants to one of the rarest.
Wood and Perlman kept track of the plants, collecting pollen and the few seeds they found.
But drought conditions in the past few years damaged the two plants while botanists were kept away because of access restrictions related to unexploded ordnance on the island.
When they got back to the site, one kanaloa was weak, and the other appeared to be dying. Bimonthly watering perked up one plant, but the other continued to decline.
"It appears to be dead. There is no vegetation on it. It is a very old plant, but there is a possibility it can still shoot out," Wood said.
The National Tropical Botanical Garden grew three plants from seeds collected on Kaho'olawe, but neither they nor the plants on the island have produced seed.
Efforts to cultivate the plants by graft, air-layer or cuttings have been unsuccessful.
Wood said the best hope now is a test-tube technique called tissue culture. He said the Kaho'olawe Island Reserve Commission has provided money to try to cultivate plants in a project involving the laboratory at Lyon Arboretum.
Wood said he will send regular shipments of tip cuttings from the potted kanaloa to Nellie Sugii at the tissue culture lab, who will attempt to grow them into new plants.
It may be the last hope for the ill-fated kanaloa.
Jan TenBruggencate is The Advertiser's Kaua'i bureau chief and its science and environment writer. You can call him at (808) 245-3074 or send e-mail to jant@honoluluadvertiser.com.
