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Leucaena leucocephala (Lam.) de Wit 1961
pronounced: loo-KEY-nuh loo-koh-KEF-uh-luh
(Mimosaceae — the wattle family)
common names: Leucaena, White Popinac, Popinac, Coffee Bush
The leaves are bipinnate, the flowers numerous and quite pretty, in spherical heads with a diameter of between 2 and 5 cm. The seed pod is anything up to 25 cm long and 2 cm wide, pendant, brown at maturity. There can be up to 22 seeds per pod.
The tree is native to Mexico, but was introduced to the Philippines in the 16th century, and from there has spread througout the tropics and sub-tropics. It is known in some circles as “the miracle bush”, because of the amount of weight that cattle gain when fed on it. There are now more than 50,000 hectares of Queensland planted with it, and graziers are being encouraged to grow more. This is alarming, as it has been declared a noxious weed in some 20 countries. It is a shrubby bush or tree often growing only to a couple of metres high, but in favourable situations it can grow up to about 18 metres.
Where it is not cropped or grazed, it can very easily become an invasive weed, and this is the case on Magnetic Island, where it infests many of our creek banks. It is very efficient at spreading its countless thousands of seeds, most of which either germinate with great rapidity or lie dormant in the soil, sometimes for decades, until the conditions are favourable. A study in Townsville counted almost 1,500 seeds in one square metre. After germination it grows into dense thickets which crowd out the native vegetation. Even if the adult trees are cut out or poisoned, the Leucaena menace has to be dealt with for years to come. Where it is controlled by grazing, this rarely happens, as the young shoots are relished by cattle, and the plants rarely set seed. It is usually planted in hedgerow systems with grass for cattle production. In some countries it is used as a shade tree over coffee and cocoa, or grown in dense rows as a living fence and used to support vine crops such as pepper and passionfruit. It has also been used as a reclamation species after mining, but is now rarely used for this because of the weed risk.
When a sap-sucking psyllid bug was accidentally introduced into Australia in the 1980’s, doing a lot of damage to Leucaena plantations, instead of welcoming it as a control agent, the agricultural scientists developed a psyllid resistant cultivar! There is also a Bruchid beetle from Mexico that eats the seed, and some of these beetles have been found in Australia; but unfortunately they only eat the seeds when on the tree, not on the ground.
Several Lepidoptera caterpillars feed on the plant, including:
The unripe pods and seeds have been used by the native inhabitants of Mexico and Central America as both food and medicine since ancient times. The young pods can be cooked and eaten as vegetables. The seeds can be used as a substitute for coffee, and when cooked can be eaten like popcorn. Hard seeds are incorporated into jewellery. Historically, the bark was used as a treatment for stomach pains, and as a contraceptive.
The tree is capable of producing a large volume of a medium-light hardwood for fuel, with low moisture and a high heating value, and makes excellent charcoal, producing little ash and smoke. The sapwood is pale yellow, and the heartwood a light reddish brown. It dries without splitting or checking. It is strong, medium textured, close-grained, and easily workable for a wide variety of purposes. Sawn timber, pit props, furniture and parquet floors are among increasingly popular uses. Its use for sawn timber is greatly limited by its generally small dimensions (usually less than 30 cm in diameter). Its branchiness limits the length of clear bole available, and means that the wood is often knotty.
Information about medicinal qualities of plants, or about their use as medicines, is for interest only, and is not intended to be used as a guide for the treatment of medical conditions.
Photographs taken at Picnic Bay 2008, 2012
Page last updated 122nd December 2016