By Jan TenBruggencate
Advertiser Columnist

The Hawai'i Biological Survey shows there are 2,264 flowering plants in the Islands, of which 918 are endemic — meaning they are found nowhere else.

That remarkable number of unique native plants reflects the isolation of the Islands. Isolated islands worldwide are known for having a high diversity of species, and here as elsewhere, it's not only plants that have evolved into new forms.

The biological survey estimates there are 24,000 species of all forms of life in Hawai'i — from bacteria to birdlife.

And much of it is rare.

"Hawai'i accounts for only about 0.2 percent of the land area of the United States, yet it has 31 percent of the nation's federally listed endangered species, and 42 percent of its endangered birds," says an article by Lucius Eldredge and Neal Evenhuis in the Bishop Museum publication, "Records of the Hawai'i Biological Survey for 2000."

"Almost 75 percent of the historically documented extinctions of plants and animals in the United States have occurred in the Hawaiian Islands," the article says.

Larger island groups have even larger collections of endemic plant species.

There may be close to 422,000 plant species worldwide, many of them not yet cataloged, writes Canary Islands botanical garden director, David Bramwell, in "Plant Talk," a publication of the National Tropical Botanical Garden.

Bramwell figures one-eighth of the total number of plants is represented in islands — even if you leave out the huge islands of Greenland and Australia.

"I arrived at a number of between 50,000 and 52,000 endemics of which about 20,000 were threatened," Bramwell wrote.

According to his estimates, Madagascar has the most unique stuff — an estimated 9,600 endemic plant species. Next comes Cuba at 4,000, the Philippines at 3,500, New Caledonia at 2,500, Hispaniola at 2,000, New Zealand at 1,620 and Japan at 1,371.

The precise numbers for the latter locations suggest fairly complete surveys have been done — surveys that may still be lacking in the other locations.

Taiwan at roughly 850 comes after Hawai'i's 918, and then other island groups with lower numbers of endemics fill in.

One thing interesting about the high numbers of plant species — in islands and worldwide — is that one-quarter or so of the estimate represents plants that have not yet been described.

"The fact that there are 100,000 and perhaps even 150,000 more plants than we had previously thought can only increase our disquiet about our capacity to meet the need to conserve biological diversity and ... to document it," Bramwell said.

Jan TenBruggencate is The Advertiser's Kaua'i bureau chief and its science and environment writer. Reach him at (808) 245-3074 or jant@honoluluadvertiser.com.