Hawai'i Gardens
Colorful native wiliwili tree can thrive in hot, dry areas
By Heidi Bornhorst
One of the most beautiful flowering trees native to dry, lowland parts of Hawai'i is the wiliwili. They bloom in our summer months. This plant grows fairly rapidly and has a mature height of about 30 feet.
The flowers look like large pea blossoms. They come in a variety of colors: apricot, chartreuse, white, yellow, red, chartreuse with an orange lip and so on. This is a trait unique to Hawai'i; most alien relatives of Hawaiian wiliwili, in the family Erythrinas, come in only one flower color (most often red or orange).
Wiliwili has a soft, light wood, and bean-like pods that twist open during the wet season to reveal ornamental orange or red, bean-like seeds. In the Hawaiian language, wili means to twist. When a word is repeated, it means the character is emphasized. Therefore, wiliwili means really twisty.
Wiliwili grows easily and rapidly from seeds. You need to replicate nature just a bit at the start, however. Place some seeds in a waterproof container. Pour hot water (just about, but not quite boiling — just "dancing" in the tea kettle, or heated for one minute in the microwave) over the seeds and let them soak for 24 hours. The seeds can then be planted, several to a 6-inch pot, or one seed to a 3-inch pot. Seeds can also be nicked or scarified with a file or clipper to enhance germination.
This combination of nicking the seed and then soaking it for 24 hours in water that was initially hot is the best way to grow a crop of wiliwili quickly (though the plants can also be grown from cuttings). To understand the reason you must treat the seeds this way, go back to where the wiliwili lives in the wild: Dry, rocky gulches on the hot sunny leeward sides of the Islands are the natural home of wiliwili. In the wild, the trees lose their leaves, then flower in the summer. The seeds develop and are ripe in winter or early spring. A good big gushing kona storm would wash seeds down the rock filled gulches. The seeds get nicked on the rocks on the tumbling journey and the lucky ones land in soaked, rich delta soil. As the rains continue, the seeds swell and sprout and the lucky ones get enough water to make a good growing start on life before the harsh, hot, dry, windy summer is again upon the land.
Wiliwili is an attractive tree for a hot, dry and sunny landscape. More of our native Hawaiian wiliwili should be grown in dry lowland gardens. We grow all the alien ones from Africa, South America, and other parts of Polynesia, yet rarely do we see our fantastic native Hawaiian one. The new developments in places such as Kapolei, 'Ewa, Kihei, Hanapepe and Kona should plan some native wiliwili into the landscapes.
Wiliwili are perfectly adapted after millions of years of flourishing in these same hot places. One drawback for some people with wiliwili in the landscape, is that the plant loses its leaves just before it flowers in the summer. If the leafless-with-flowers look is not acceptable, interplant wiliwili with evergreen plant material such as naio, manele or alahe'e. Non-native evergreen or flowering trees or shrubs like rainbow shower, plumeria or kolomona may also be interplanted with wiliwili. Polynesian introductions like kou and milo are also good landscape choices. This is what we call a "hapa haole landscape mix," or hapa Hawaiian, if you prefer.
Wiliwili is naturally pollinated by native birds. Nowadays many birds, both native and introduced, congregate and feed on the pollen and nectar of blossoming trees. The Hawaiians made lei from the attractive blossoms and seeds, and surfboards, ama (canoe outriggers) and net floats from the lightweight, buoyant wood. Hand puppets were carved from the soft wood, too.
The scientific name for wiliwili is Erythrina sandwicensis. It is in the bean and pea family, Fabaceae, along with other native Hawaiian hardwood trees, including koa, koaia, mamane and uhiuhi.
One of the best places to see wiliwili easily is at the bottom of the Likelike Highway, near the Bishop Museum. Tommy Boyd, who manages the museum grounds, displays several choice color forms that can be well enjoyed as you drive by, or go in and park and check them out form the other side. The moss rock wall and bright bougainvillea are a nice landscape combo with the color forms of wiliwili.
An ancient grove still stands at Koko Crater Botanical Garden, and all the trees there are protected by law — the city's exceptional trees ordinance, which prevents their being cut down, bulldozed, or even trimmed without permission. They also grow in Moanalua Gardens, at Ho'omaluhia, and at Waimea Arboretum. There is a group along the Moanalua Freeway by Fort Shafter on the makai side of the road.
In some dry areas such as Kekaha mauka as you head up to Koke'e on Kaua'i, Kihei on Maui and Kona on the Big Island, they still flourish and can be easily seen as you drive along. Dry gulches still grow some wiliwili, but fires, sadly too common in dry areas, always destroy these and other native Hawaiian plants. After fires come aggressive weeds like that pernicious fountain grass on the Big Island, that can out-compete wiliwili and other natives.
Recently, intricate, carefully crocheted lei of wiliwili seeds have become very popular. Of course, the most beautiful is the lei made from the large bright orange red Hawaiian wiliwili. (The aline, imported ones have seeds that are dark purple-brown like a kidney bean, tan or white and some have smaller red, orange or red and black seeds). Wanting to have the seeds on hand to create lei is a great reason to grow this vanishing tree in your own garden. The flowers also make an awesome lei, especially if you grow them at home and then pick them at their peak of freshness and combine several of the lovely pastel colors that the blossoms come in.
Heidi Bornhorst is director of Honolulu's five botanical gardens.
