Agroforestree Database

Local names:
 Amharic (akacha saligna), English (willow wattle,weeping wattle,Port Jackson willow,orange wattle,golden-wreath wattle,blue-leafed wattle)

Acacia saligna is a dense and multi stemmed, thornless, spreading shrub or a single-stemmed, small tree up to 9 m in height; bark is smooth and grey to red-brown on branchlets becoming dark grey and fissured with age.

Leaves alternate, simple, flattened phyllodes, varying from very narrow to lance-shaped, about 10 times as long as wide, mostly 8-25 cm long and 0.5-2 cm wide, straight or slightly curved to the side, long, pointed and tapering at both ends like ribbons, hairless, often drooping, dull blue-green to whitish, with a permanent midvein and many fine side veins; large dotlike gland 1-2 mm or more in diameter at base of upper edge of phyllode. 

Flower clusters (heads) like balls, mostly 2-10 (sometimes 1), on stalks along axis (racemes) to 8 cm long at base of leaf; round, bright yellow or deep golden heads, 7-10 mm in diameter, with many (25-55) crowded, tiny flowers, abundant and showy; flowers stalkless, 3-4 mm long, mostly hairless, composed of calyx 1.5 mm long with conical tube and 5 short, rounded lobes, often finely hairy on edge; corolla of 5 narrow, long-pointed petals, 2-3 mm long, united near base; many threadlike stamens, pistil with hairless ovary and slender style.

Fruits very narrow, 8-12 cm long and 4-6 mm wide, straight and flattened. There are 6 to 10 beanlike seeds, each 5-6 mm long x 3-2.5 mm wide, dark brown to black, shiny.

The generic name ‘acacia’ comes from the Greek word ‘akis’, meaning a point or a barb. The specific name means ‘willowlike’ and describes the phyllodes.

Ecology

A. saligna grows mainly on sandy, coastal plains, but it is also found in a wide variety of environments, from swampy sites and river banks to small, rocky hills (often granitic) and slopes of coastal ranges. It is also found by creeks and disturbed roadsides. The plant tolerates salt spray, soil salinity and alkalinity. The associated vegetation types include open, dry evergreen forest, temperate woodland and semi-arid woodland.

Native range
Australia

Tree management

Production for browse and wood can begin 3 years after planting out, gradually building to 6 years. The impact of various management methods on long-term productivity is not well understood. In Mauritius, the management options tried include trimming followed by direct grazing and direct browsing with periodic pruning. A rotation of 7-10 years or coppicing may be used. In Mediterranean countries, firewood from A. saligna is harvested on a coppice rotation of 5-10 years. Human interference and grazing should be discouraged for rapid success. Lupines should be sown where necessary to enrich the ground cover.

Seed storage behaviour is orthodox. There are about 14 000-25 000 seeds/kg.

A. saligna grows mainly on sandy, coastal plains, but it is also found in a wide variety of environments, from swampy sites and river banks to small, rocky hills (often granitic) and slopes of coastal ranges. It is also found by creeks and disturbed roadsides. The plant tolerates salt spray, soil salinity and alkalinity. The associated vegetation types include open, dry evergreen forest, temperate woodland and semi-arid woodland.

A. saligna produces a large number of viable seeds, and young plants can often be found in their hundreds under mature trees, promoting the rapid spread of the species and directly contributing to its weed status. The seeds germinate easily. They are normally treated with boiling water for 1 minute, but nicking the seed coat, soaking seed in sulphuric acid, and exposing seed to dry heat are also effective. Successful micro-propagation techniques using tissue culture have also been used.

In Australia it has been used in the rehabilitation of sand mining areas.

Erosion control:  A. saligna is one of the best species for binding sand. It has been used in North Africa, the Middle East and South Africa for coastal sand dune fixation, and in Uruguay for gully erosion control.

The phyllodes, young shoots, pods and seeds, whether fresh or dry, are rich in protein and are non-toxic and palatable to both sheep and goats. They are particularly valuable seasonally when other forage is scarce. The chemical composition of the leaves shows dry matter (50-55%), crude protein (12-16%), crude fibre (20-24%), crude fat (6-9%) and ash (10-12%). Re-growth of established bushes is so good that A. saligna can be completely grazed off without harming the plant.

Plantations for firewood have been established in some Mediterranean countries. The wood is reported as sappy, light and not popular for firewood. A. saligna can withstand some shade and can be grown as an understorey beneath pines or eucalypts for energy in villages.

Fibre:  In Tunisia the wood has been successfully processed into particleboard.

Timber:  A. saligna is used for vine stakes and small agricultural implements. 

Shade or shelter:  A. saligna is useful for windbreaks.

Tannin or dyestuff:  In the past, the tree was planted for tannin production from the bark.

Gum or resin:  The damaged bark exudes copious amounts of a very acidic gum that shows exceptional promise for use in pickles and other acidic foodstuff.

Nitrogen fixing:  The tree nodulates with certain strains of Rhizobium. As with many other acacias, it forms associations with Vesicular Arbuscular mycorrhizal (VAM) fungi.

Ornamental:  A. saligna is widely planted as an ornamental.