Erythrina sandwicensis Degener

Erythrina sandwicensis is a small deciduous tree 5-15 m tall with a short, stout, crooked or gnarled trunk, 30-90 cm in diameter. Branches spreading, stiff, crown broad, thin, wider than it is high. Bark smooth, light to reddish brown, becoming slightly fissured and thin with age; with scattered stout grey or black spines up to 1 cm long. Twigs stout, green with yellow hairs when young and scattered blackish spines. Leaves alternate, compound, 13-30 cm long, with a long slender leafstalk. Leaflets three, short-stalked; terminal leaflet larger than the other two. Leaflets are 4-10 cm long and 6-15 cm wide. Flower racemes hairy, yellow, stalk up to 7.4 cm. Flowers crowded in a mass, 7.5-15 cm long and short stalked. Flower color may be orange, yellow, salmon, green and white. Pods approximately 10 cm long and 13 cm broad, flattened, pointed at both ends; containing 1-4 seeds, blackish and slightly narrowed between seeds. Seeds elliptical, shiny red orange 13-15 mm long. Erythrina comes from the Greek word ‘eruthros’-red, alluding to the showy red flowers of the Erythrina species.

E. sandwicensis loses its leaves in the late summer or early fall (August to October), and leaves appear again during early spring to mid-summer (March to July), usually after flowering has occurred. Observations on Maui indicate that leaves drop during the dry periods of late spring or early summer (May to June). The tree flowers during the fall (September to November), flowers hermaphroditic. Leaves reappear after the first southerly storms in the late fall (November). Differences in observations may be tied to variation of annual soil moisture, and the considerable heterogeneity of flowering, leaf loss, and seed set within a single stand. Mature pods are found on the trees during winter months (December to February).

E. sandwicensis prefers well-drained soils.

E. sandwicensis is endemic to the leeward side of the Hawaiian Islands in lowland environments. It was once a dominant component of ancient endemic Hawaiian dryland forests. It is found where rainfall is usually concentrated between November and March, and survives extended drought and high winds. It thrives in the hot, dry foothills and lowland dry forest.

E. sandwicensis can be easily propagated by seed or cuttings. For nursery propagation 1-litre containers with a 1:1:1 mixture of perlite, vermiculite, and potting soil are suggested. A small amount of 14- 14-14 N-P-K slow release fertilizer can be added to the potting mix. If vesicular arbuscular mycorrhizal (VAM) inoculant is available, it should be mixed in the potting media as well. Seeds should be planted 4 cm deep and inoculated with rhizobia by irrigating the seedlings with a suspension of peat inoculant in water. Seedlings should be kept under shade until the first 2 or 4 true leaves appear and watered as needed. Over watering may cause damping-off. After two weeks, plants should be placed in full sun and watered with liquid fertilizer solution containing N- P-K plus micronutrients. Cuttings should be a minimum of 2.5 cm in diameter and 30 cm long and air-dried for at least 24 hours before planting. The base of the cuttings can be coated with rooting hormone. The cuttings should be placed in the ground to a depth of at least 15 cm, and the soil kept moist. Sealing the top surface of the cuttings with wax or tree-wound dressing will help to prevent drying out. Seedlings are ready for out planting when stems are sturdy and well hardened, after approximately four months in the nursery.

E. sandwicensis should be planted on sites similar to its natural environment. Sites are recommended that have well-drained soil and receive full sun. Planting holes should contain slow release fertilizers and watered once a week for the first month. If watering is not possible or if conditions are particularly harsh, the leaves of the seedlings may be trimmed or the tops cut off entirely.

E. sandwicensis seedlings may be susceptible to damping-off problems. Powdery mildew fungi will attack the leaves in humid environments. Stem boring caterpillars have caused seedling mortality. Red spider mites are commonly associated with wiliwili. The tree is not suited for areas with high rainfall.

To improve germination, seeds should be mechanically scarified by nicking the seed coat and soaking in water (at room temperature) overnight.

Reclamation: E. sandwicensis is used in revegetation programs of highly eroded areas in Hawaii. Nitrogen fixing: The tree forms a nitrogen fixing symbiosis with Bradyrhizobium species. Boundary or barrier or support: It has been frequently planted as a live fence on account of readiness with which it takes root when planted in the ground. Other services: The wood, seed and flowers were traditionally used in Hawaii, and the tree is integral to many Hawaiian legends and proverbs.

Timber: Wood is lightweight and was used by ancient Hawaiians for fishing net buoys, surfboards and outriggers on canoes. More recently, wood from the wiliwili has been carved into imitation whale-tooth necklaces. Tannin or dyestuff: It was also burned to make charcoal for use as color pigment to blend with other ingredients in making paint. Other products: The bright red seeds were used for making leis.