This is a three-part story – first, of some sensational landscape trees that the Old Hawaiians used to make surfboards and outriggers. Second, it’s the story of a native Hawaiian plant that's tough as a rhinoceros (and just as endangered). Finally, this is the story of Hawai‘i's vulnerability to lightning-quick biological invasions. All three of these tales are compressed into a single Hawaiian word: "wiliwili."

Of all the flowering trees that have been imported to Hawai‘i over the years—planted to beautify our roadsides, parking lots, and campuses—Erythrina belongs at the top of anyone's most-preferred list. When they're not in bloom, they provide billowing canopies of dark-green foliage, dense and cool. When they do bloom—hold on, Joe, stop the car. The floral clusters erupt in super-saturated tones of red.

Some half-dozen species of Erythrina are common in Hawai‘i. Another 90 grow in Hawai‘i's botanic gardens. None escape cultivation to become weeds. Leaves have three leaflets, like overgrown clover leaves. Individual flowers follow the sweet-pea plan. The fruit looks like a woody bean pod that was shrink-wrapped to fit a few bright red beans. Clearly Erythrina belongs in the legume family. Peculiar traits: armed with prickles, and deciduous—drops all leaves annually, at odd times. Common names include "coral tree" and "tiger's claw," but in Hawai‘i they're all "wiliwili."

True wiliwili is one of a kind—Erythrina sandwicensis. (as in "the Sandwich Islands," the name given to the Hawaiian Isles by their first European visitors). Endemic, this species thrives in parched, wind-blasted leeward shorelines—hot coral plains of Ewa, stark lava flows of Kona, and the bleak terrain of Kahikinui on the back side of Haleakala. Gnarly and wide-spreading, 30 feet tall, wiliwili forms broad, stocky trunks and limbs. The thin bark has a burnished, almost metallic gray-gold effect. Each tree has its own flower color, ranging from pale red through orange and yellow to greenish-white, and these differently colored trees grow side-by-side like zinnias in a window-box.

The Hawaiians harvested wiliwili's buoyant lumber. The lightest of all the native woods, it was ideal for surfboards, outriggers, and net floats.

September is height of the dry season on leeward Haleakala's lava-and-scrub slopes. Out there, even the most aggressive weeds—Christmas berry, haole koa, lantana—fight for life in the whipping winds. But wiliwili responds to September's austerity with a stroke of native intelligence. It drops leaves entirely—takes a vacation from the struggle, so to speak—and throws itself into sex. It flowers.

This tree is almost the only survivor of the original forests that once cloaked those slopes, delicate forests that have largely succumbed to foraging cattle. Perhaps wiliwili survived because it's one of the few Hawaiian plants armed with thorns (that Erythrina prickliness!). However it survived, wiliwili is now a symbol of hope for the tattered native flora.

Now here's the sad part.

No one had ever heard of the erythrina gall wasp, a creature the size of a sand grain, until entomologists found it in Singapore, Mauritius, and Reunion Island in 2004. They named it Quadrastichus erythrinae. This wasp injects an Erythrina buds with a toxin then lays its eggs. The bud swells into a leafless, cancerous lump in which wasp larvae feed and shelter.

In the normal way of things, such gall-wasp lumps are like warts or barnacles—not a crisis. But in 2005, somehow, these minute creatures got to Hawai‘i. Unchecked by natural predators, they've had an orgy. Starting on O‘ahu and spreading within months to all the other islands, they have turned Hawai‘i's ornamental Erythrina trees into lumpy skeletons, leafless horrors starving to death where they stand.

Last year, it looked as though the native wiliwili, so remote and so tough, still unaffected, could escape the plague. Research biologist Art Medeiros was giving them a 50-50 chance. However, at the time of this writing, we are getting our first reports of galls on the last native trees of leeward Haleakala.

Scientists working for the state have identified some natural predators of the erythrina gall wasp. They want to release these predators, of course, to help abate the plague. But they need time for study. It is foolish to release yet another "invasive species"—wili-nilly.

In terms of one genus, Erythrina, Hawai‘i is now in a state of shock verging on tragedy. Most tourists will never know this. But perceptive visitors have to remember that Hawai‘i is not a Disneyland. It is an ecological treasure unique on earth—frail, changing, and honorable.