We’ve now got three wiliwili trees scattered through the food forest, most recently one planted right below a pheasantwood I’m slowly phasing out anyway.
The Basics
Wiliwili, Erythrina sandwicensis, is one of the true native Hawaiian trees, endemic to this island chain and found nowhere else on earth.
Origin and Habitat
It grows in dry, leeward forest, exactly the kind of hot, low rainfall coastal zone that’s become one of Hawaiʻi’s most threatened ecosystems. Wiliwili is drought deciduous, meaning it drops its leaves and goes dormant during the dry season, which is the opposite behavior of most things I plant here.
What It Looks Like
A gnarled, spreading tree with light, corky bark and trifoliate leaves, three leaflets to a stem, that drop entirely during the dry season. Once bare it puts on a wild show of curled flowers that can range from orange and red to salmon, yellow, or even pale green depending on the individual tree, which is part of what makes a wiliwili grove such a striking, unpredictable thing to walk through in bloom. Afterward it produces bright orange and red seeds that get strung into lei.
Uses and Flavor
Not edible, but culturally significant. The seeds go into lei, and the famously lightweight wood was traditionally used for fishing net floats, outrigger ama, and papa heʻe nalu, the original Hawaiian surfboards, since it floats so well and is easy to shape. It’s one of those trees where the value was never in eating it, but in everything it made possible around the water.
Growing It Here
Wiliwili wants full sun, good drainage, and honestly not much water once established. If anything it’s more forgiving of drought and neglect than most of what else grows around it, which is a nice change of pace from a lot of the moisture loving exotics we baby along here. It doesn’t love being crowded either, since it’s used to growing in open, dry forest rather than a dense, shaded food forest setting, so I’ve made sure to give ours room and light rather than tucking them in among taller trees.
Pests and Diseases to Watch For
This one has a real history. The erythrina gall wasp arrived in Hawaiʻi on Oʻahu in 2005 and spread across the islands fast, causing widespread dieback and killing a lot of wiliwili in just a few years. The good news is a host specific biocontrol wasp, Eurytoma erythrinae, was released starting in 2008, and by 2011 around ninety percent of sampled wiliwili trees had recovered their full canopy. A second biocontrol, Aprostocetus nitens, has been in the works since to help further, since flowering and seed production are still affected even with the recovery so far. Every wiliwili we get established still feels like it counts for something given that history.
Kenta’s Take
Dry forest like the kind wiliwili calls home is one of the most reduced ecosystems in the state, some estimates put what’s left at a small fraction of what used to exist before people, cattle, and fire showed up. Ours are still young. Ask me again in a few years how the flowers turned out.