Today's post celebrates the wiliwili, Erythrina sandwicensis, or Hawaiian coral tree, an endemic tree so rich in history and with so many interesting twists (yes, wili means twist), I was inspired to share what I have learned about it. First, it's the only member of its genus to be native here. It is also one of the few native trees that is deciduous, losing its leaves when in bloom, often in the late spring and summer, though reports on this vary. Yet another unusual feature is it's spiky trunk, which become less pronounced as the tree matures. You'll find it on the leeward slopes, from sea level to about 2000 feet, as it prefers dry habitat. Leaflets are wider then they are long, and come in groups of three. The seed pods usually hold one to three stunning orange to red seeds (color variation is possible) which are used in lei making. Wiliwili means to twist and twist, referring to the way the pod winds opens to expose the seeds. Flowers are clustered, curved and come in a variety of colors including greenish-white, yellowish, salmon, and orange, and are pollinated by birds. The tree itself averages about thirty feet in height.
Because the wood of the wiliwili has a low density, it was used to make everything from fishing net floats, to surfboards, to outrigger booms. And it's a tough old tree: drought tolerant, wind tolerant, and one of the few natives to survive on Kaho'olawe. Its nitrogen-fixing abilities also make it easier for other plants to get started on lava flows and eroded areas. Ah, but it has its challenges. Enter the beasts: the Erythrina gall wasps. They were first detected in July of 2005, and quickly spread throughout the islands, wrecking havoc on the wiliwili and other tropical coral bean trees. Curled up leaves and bulbous stems and petioles signaled the presence of the wasp, as the eggs of the wasp laid within the plant's tissues began to swell with their growing larvae. Some feared 100% mortality of the native wiliwili, as foliage loss and an inability to transpire meant the quick deterioration of the trees.
Seeds were collected and banked, while specialists worked to control infestations. By 2008, the Hawaii Department of Agriculture employed the parasitic services of a second wasp brought all the way in from Africa, Eurytoma erythrinae. Let the battle begin. 5000 of these teeny tiny wasps (a few millimeters in length) were released, and quickly laid their eggs. Where? Right inside the gall created by the gall wasp. When their larvae hatched, they dined on the larvae of the gall wasp. I know... not a pretty visual, but war is hell. While the verdict is still out on the fate of these keystone trees of Hawaii's dryland forests, it seems that there is good progress being made. If there is a tree out there that can get up after a punch like that, it's the wiliwili.
welcomes you to visit with the all the wonderful flora and fauna that we share this lovely aina with.