Common name: Ohi'a lehua

A  native of the Hawaiian Islands, this ornamental and honey plant is highly variable in the wild. Some specimens grow into trees reaching up to 30 m (100 ft) tall with a trunk diameter of 90 cm ( 36 in), others growing only into a shrub.

In parks and gardens, it is usually encountered as a small tree 5 to 10 m (16 to 33 ft) tall, with a ragged trunk supporting an open, rounded or irregular crown. The bark on young trees is light grey and smooth, with age becoming rough, fissured and flaking.

The leaves are variable in shape and size, either elliptical, oval or rounded and from 1 to 7.5 cm (0.4 to 3 in) long. They emerge reddish, become grey-green with a leathery texture and are arranged opposite along at the ends of the branches.

The flowers resemble powder-puffs, having long erect filaments, either bright red, orange or yellow, depending on the variety. They are borne in showy clusters at the tips of the branches and come into bloom from spring to summer. Small, woody, bell-shaped seedpods follow, turning brown when mature with many tiny seed inside.

Use

The flowers are much-appreciated in Hawaii. Together with the tree's compact size, they have made it a popular home-garden tree there.

The flowers produce abundant nectar that attracts nectar-feeding birds and honeybees. It is classed as a major honey plant in Hawaii, and the honey is often found on sale at farmers markets there. It is whitish to light amber honey, with a mild toffee flavour, creamy texture and crystallises to a fine grain. 

The wood is hard and heavy, averaging about 700 kilograms per cubic meter (44 lbs per cubic ft) and has reddish-brown heartwood with a fine, even texture that polishes well. However, it is not naturally termite or rot-resistant, and there is high shrinkage on drying, limiting its use outdoors. The sawn timber is used mainly for interior flooring and the small-diameter roundwood cut for carvings and firewood.

It is one of the first species to naturally colonise new land created by lava flows in Hawaii. It can disperse its seed on the wind and establish on bare soil, its roots extensive and penetrating.

Climate

Ohi'a lehua grows naturally in moderately humid to very humid subtropical and tropical lowland to high elevation climates, generally areas with annual lows of 10 to 19°C, annual highs of 20 to 28°C, annual rainfall of 800 to 7000 mm and a dry season of 4 months or less. However, it reaches its best development as a timber tree in mid-elevation areas with annual rainfall of 1000 to 3000 mm.

Growing

New plants are usually grown from seed, which remain viable for up to nine months. Performs best on free-draining clay and loam soils of an acid to neutral nature, generally with a pH of 4.0 to 7.5, and on sites with full to partial sun exposure. It usually develops into a shrub on poorly drained, rocky or infertile soil or at high elevations.

Problem features

There is a risk of it escaping cultivation and becoming a weed due to its ability to disperse its seed by wind and its ability to establish on bare or compacted soils.

Books

• Barwick, M., et al. 2004, Tropical & subtropical trees : a worldwide encyclopaedic guide, Thames and Hudson, London

• Burns, R.M. & Honkala, B.H. 1990, Silvics of North America (Volume 2) : Hardwoods, Agricultural Handbook 654, U.S. Department of Agriculture (USDA), Washington D.C.

• Elevitch, C. R. 2006, Traditional trees of Pacific Islands: their culture, environment and use, 1st edition, Permanent Agriculture Resources, Holualoa, Hawaii

• Little, E. L. & Skolmen, R. G. 1989, Common forest trees of Hawaii (native and introduced), Agricultuural Handbook No. 679, Forest Service, U.S. Department of Agriculture, Washington, D.C.

• Rauch, F. D. & Weissich, P. R. 2000, Plants for tropical landscapes : a gardener's guide, University of Hawaii Press, Honolulu

• Rauch, Fred D. (Fred Donald) & Weissich, Paul R 2009, Small trees for the tropical landscape : a gardener's guide, University of Hawai'i Press, Honolulu, T.H

• Vozzo, J. A 2002, Tropical tree seed manual, U.S. Department of Agriculture (USDA), Forest Service, Washington D.C.