Acacia ligulata Seeds | Sandhill Wattle
LATIN NAME: Acacia ligulata
COMMON NAME: Sandhill Wattle, Umbrella Bush
Plant Profile
Sandhill wattle is the shrub that holds the dunes together across the arid interior of Australia, and it does it with a shape that reads as deliberate. It is dense, rounded and often wider than tall, one to four metres in most places, with a flat-topped canopy that gives it the second of its common names, umbrella bush. The phyllodes are narrow, thick and blue-green, held upright enough to shed the worst of the sun. In spring the plant disappears under golden balls of flower, and the pods that follow are curled and papery. It grows on deep red sand, on the lee slopes of dunes and along dry watercourses, in country that gets perhaps two hundred millimetres of rain a year and sometimes none. It is one of the first plants to return after fire, and one of the few that will hold a moving dune long enough for other species to establish.
Science & Biotechnology
Acacia ligulata is a seeding acacia rather than a resprouter in most of its range: fire kills the adult, and the population returns from soil-stored seed, which carries a hard coat and a fat-rich aril. Ants move the seed into nests, where it escapes granivores and sits until heat or abrasion breaks the coat. The species is andromonoecious in part, with both bisexual and male flowers in the same head, a pattern that increases pollen donation without reducing seed set. Root systems reach deep and also form shallow laterals that capture light rain, a dual strategy common in dune shrubs. It nodulates with rhizobia and fixes nitrogen, which matters on sand that is almost pure silica. The name ligulata refers to the strap-shaped phyllode, not to a ligule in the grass sense.
Uses & Benefits
The plant is a dune binder before it is anything else. Its roots and its habit of trapping sand build the lee slope of a dune, and it is planted in stabilisation work across the arid zone. Aboriginal groups in the interior have used the seed as food, roasted and ground after the aril is removed, and the wood for small implements and fuel; the seed is one of the bush foods now being reassessed for commercial potential, though volumes are small and harvest is wild. It is also a useful fodder shrub in drought, since stock browse the phyllodes when little else is green. In gardens it is a low-water ornamental for dry climates, quick to flower and good on a bank. As with most acacias, the bark is astringent and the gum edible but not collected here.
Growing from Seed
Break the seed coat with hot water, or nick the hard end with a file and soak overnight; untreated seed may sit for years. Sow into a very free-draining mix of sand, fine gravel and a little compost, cover to the seed’s own depth, and keep at 20 to 26 degrees in full sun. Germination is fast, often within ten days, and the seedlings grow away strongly. Water sparingly but deeply; this is a plant that resents a wet root zone far more than it resents heat. Pot on before the roots coil, and plant out in autumn so the roots can settle before summer. Stake only if the site is windy, and avoid rich fertiliser, which produces soft growth and few flowers. It will tolerate light frost but not prolonged freezing.
Our Take
A dune plant for dry, sandy ground, quick from treated seed and useful where nothing else will hold. Plant it in poor soil and leave the hose alone.
Related Reading
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