Albizia procera (Roxb.) Benth.
(Mimosaceae – the wattle family)
common names: Forest Siris, White Siris
Albizia was named for Filippo del Albizzi, an 18th century Florentine nobleman who introduced Albizia julibrissin (the Persian Silk Tree) into cultivation; procera is from the Latin procerus, high, tall.
2010 was an excellent season for these magnificent trees, a riot of blossom in early October. The scent of the flowers is very strong and sweet, redolent of honey. The ground under the trees is a carpet of blossom, almost too beautiful to walk on. There are quite a few of these trees on the island: the one photographed is by the boat ramp car park in Picnic Bay.
The Forest Siris is a native of Australia and Oceana (including PNG), south-east Asia, and south Asia. It is a tree with an open canopy, up to 30 m tall, with a trunk of up to 35 cm in diameter (occasionally up to 60 cm). The bole is straight or crooked, up to 9 m tall. The bark is smooth, pale grey-green, yellowish green, yellowish brown or brown, with horizontal ridges; the underbark is green, changing to orange just below the surface, the inner bark pink or straw-coloured; the branches are terete and glabrous.
The leaves are bipinnate with 2–5 pairs of sub-opposite pinnae; the rachis 10–30 cm, glabrous with a gland 1–2.5 cm above the base; the gland is narrowly elliptic, 4–10 mm long, sessile, flat and disk-like or concave with raised margins; the pinnae 12–20 cm long, glabrous; the leaflets 5–11 pairs per pinna, opposite, asymmetrically ovate to sub-rhombic, 2.5–6 by 1–3 cm; the base asymmetrical; the apex rounded or sub-truncate.
The inflorescence is composed of pedunculate clusters collected in an axillary panicle up to 30 cm long; the peduncle 1.5–2.3 cm long, 2–5 together; flowers 15–30 per cluster, sessile, uniform (the central flowers usually larger than the marginal ones), and bisexual.
The fruits are rich red or reddish brown flattened pods 10–20 by 2–2.5 cm, thin and papery, with distinct marks over the seeds. Each mature pod contains 6–12 seeds, and usually remains on the tree until the whole twig bearing the pods is shed – quite a few of last year’s pods are often still there when the following year’s flowering is in progress.The seeds are small, greenish brown, elliptical to round, flat, with a hard, smooth seed-coat.
In the Philippines, cooked leaves are eaten as a vegetable. In times of scarcity the bark can be ground with flour and eaten. The leaves are used as fodder in some countries, and eaten by cattle, buffaloes, goats, camels and elephants. Excellent charcoal can be prepared from the wood. The wood is also suitable for pulping for use in paper-making. There is a great deal of sap-wood (the tree is a fast grower), but the heart-wood is hard and heavy, and used for construction, furniture, veneer, flooring, agricultural implements, carts, cane-crushers, oil-presses, rice-pounders, carving and boat-building. When injured, the stem exudes large amounts of a reddish brown gum similar to gum arabic. All parts of the plant are used medicinally. Pounded bark and leaves are used as a fish-poison, and the leaves are also known to have insecticidal properties.
Photographs © Donald Simpson taken 2010, Picnic Bay