Common name: Guest tree

Guest tree is an ornamental and minor timber tree originating from a wide geographical area, its natural range extending from India through Southeast Asia to northern Australia and the Pacific.

It is fast-growing and, on favourable sites, reaches heights of up to 20 m (65 ft), though is more commonly 10 to 15 m (33 to 50 ft) tall with a short, sometimes crooked, trunk and with upright branches forming a densely leafy rounded crown. The bark is grey and fissured.

The leaves are heart-shaped, up to 15 cm (6 in) long, sharply pointed at the tip, dull green on top and pale green underneath. They are alternately arranged along the ends of the branches and remain on the tree throughout the year.

From late spring to autumn, small, pale pink flowers bloom in large clusters. They are followed by curious five-lobed, air-filled seedpods with a papery coat, allowing the wind to carry them and their seed a long distance from the parent tree. 

Use

Guest tree is cultivated as a street and landscape tree in its native range for its shapely form, showy flowers and unusual, five-lobed seedpods. It is particularly suited to coastal areas due to its tolerance to salt spray.

A minor timber tree, the wood is used mainly in woodcraft and turnery. It is a whitish, lightweight wood in the 300 to 400 kgs per cubic meter (19 to 25 lbs per cubic ft) range. Artisans are particularly interested in the knotted pieces, which they use to craft ornate knife and dagger handles. The limbs, branches and off-cuts of the trunk-wood make good firewood.

In the Philippines, the bark is stripped and woven into rope used to harness livestock. 

The flowers produce abundant nectar and attract foraging honeybees. However, there does not appear to be much information on its value as a honey plant.

The leaves reportedly have insecticidal properties and are used in traditional medicinal preparations to treat head lice.

Climate

Grows naturally in sub-humid to humid tropical lowland climates, generally areas with annual lows of 18 to 25°C, annual highs of 27 to 35°C, annual rainfall of 700 and 3500 mm and a dry season 7 months or less. However, it reaches its best development as a tree in areas with annual rainfall of 1700 mm or more.

Growing

New plants are usually started from seed. Performs best on free-draining loam and sand soils of an acid to alkaline nature, generally with a pH of 5.0 to 7.5, and on sites having full to partial sun exposure.

Problem features

Guest tree has escaped cultivation and is recorded as a weed of the environment in Hawaii and as naturalised in other areas of the United States.

The bark and leaves are known to have poisonous properties.

Books

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

• Brown, William Henry, 1884-1939 & The LuEsther T Mertz Library & the New York Botanical Garden 1919, Philippine fiber plants, Bureau of Printing, Manila

• Elevitch, C. R & Wilkinson, K. M. 2000, Agroforestry Guides for Pacific Islands, 1st ed., Permanent Agriculture Resources, Holualoa, Hawaii

• Little, E. L. 1974, Trees of Puerto Rico and the Virgin Islands, Vol. 2, United States Department of Agriculture (USDA), Washington D.C.

• Macmillan, H. F. 1943, Tropical planting and gardening : with special reference to Ceylon, 5th ed, Macmillan Publishing, London

• Martin, F. W & Ruberte, R. M. 1975, Edible leaves of the tropics, U.S. Agency for International Development (USAID), and the Agricultural Research Service, U.S. Department of Agriculture (USDA), Mayaguez, Puerto Rico

• Randall, R. P. 2002, A global compendium of weeds, R.G. and F.J. Richardson Press, Melbourne

• Reyes, G. 1992, Wood densities of tropical tree species, U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station, New Orleans, Louisiana