Albizia lebbeck Seeds | Woman’s Tongue Tree

Woman's Tongue Tree (Albizia lebbeck) with powderpuff pale yellow flowers and long straw-coloured pods — Woman’s Tongue Tree (*Albizia lebbeck*): Fabaceae, the siris of the dry tropics, grown for shade, fodder and the rattle of its pods.

LATIN NAME: Albizia lebbeck

COMMON NAME: Woman’s Tongue Tree, Siris

Plant Profile

The woman’s tongue tree is a fast-growing, spreading deciduous tree, fifteen to twenty-five metres tall in good conditions, with a broad, umbrella-shaped crown and a trunk that is smooth and grey when young and rough with age. The leaves are bipinnate, divided into several pairs of pinnae, each carrying a row of small, oblong leaflets, and the whole canopy has a fine, feathery texture that filters light rather than blocking it. In the dry season the tree is briefly bare, and the new leaves come with the first rains.

The flowers are the reason for the tree’s other common name, the powderpuff. They are hemispherical heads of long stamens, pale greenish yellow, faintly fragrant, hanging in clusters through the warm months, and they are worked by bees and by bats in some parts of the range. The pods that follow are the source of the curious name: they are broad, flat, straw-coloured and fifteen to thirty centimetres long, and when they dry they rattle in the wind with a sound like a tongue wagging. The species is native to the Indian subcontinent, Southeast Asia and northern Australia, and it has been planted so widely across the dry tropics that its original range is uncertain.

Science & Biotechnology

Albizia lebbeck is a legume, and it fixes nitrogen through root nodules in symbiosis with rhizobia, which is the basis of its use in agroforestry. It grows on poor, compacted and saline soils, tolerates both drought and short flooding, and produces a large quantity of leaf litter that raises soil organic matter and improves structure. Studies in India, Africa and Australia have measured its growth, its nitrogen contribution and its effect on companion crops, and it is one of the standard species in the reclamation of sodic and alkaline land.

The foliage is also a fodder resource. Leaf meal contains fifteen to twenty-five per cent crude protein, and feeding trials with goats, sheep and cattle have shown it to be palatable and digestible, though the tannin content limits how much can be included. The bark and pods contain saponins and flavonoids, and extracts have been examined for anti-inflammatory, antimicrobial and antidiabetic activity, with most of the work still at the level of animal models and cell culture. One caution is allergenic: the pollen of Albizia is a recognised cause of respiratory allergy in the tropics, and the tree should not be planted close to windows in areas where it flowers heavily.

Uses & Benefits

The tree’s main role is shade and shelter in hot, dry climates. Its crown is broad enough to protect livestock and crops, it grows fast enough to be useful within five years, and it coppices and pollards well, so it can produce fuelwood on a short rotation. The wood is moderately hard, takes a good finish and is used for furniture, flooring, turnery and agricultural implements, though it is not durable in the ground. The pods and leaves are fed to livestock, and the flowers are a useful bee forage.

In the garden it is a shade tree for a large property, a park or an avenue in a warm climate, and it is often grown for the sheer speed with which it creates a canopy. It is not suitable for small gardens, because the crown is wide, the litter is heavy and the roots are extensive. It is also invasive in some tropical and subtropical regions outside its native range, particularly on Pacific islands and in parts of the Caribbean, where it forms dense stands in disturbed ground. It should be planted with that risk in mind.

Growing from Seed

The seed coat is hard and impermeable, and germination without treatment is slow and uneven. Pour hot water at about eighty degrees over the seed and leave it to soak for twelve to twenty-four hours, or nick the coat with a file. Sow into a free-draining mix, cover lightly, and keep at twenty-five to thirty degrees. Germination begins in one to two weeks and is usually vigorous.

Pot the seedlings on as soon as they are large enough, and grow them in full sun. Plant out when they are thirty to forty centimetres tall, into any well-drained soil, including poor and alkaline ground, and water through the first dry season. The tree grows extremely fast, often a metre and a half in its first year, and may need staking and formative pruning to develop a single leader. It is frost tender when young and should be protected for the first two winters in cool climates.

Our Take

A tree for space, heat and poor ground, and one of the fastest ways to make shade in a dry climate. Give it room and it will do the rest, though it should be kept away from small gardens and from places where it might spread.

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