Citation: J. M. Black, Trans. R.Soc. S.Aust. 42:173 t.18 (1918).

Derivation: rivalis (L.)—growing by streams.

Synonymy: Not Applicable

Common name: silver wattle

Description:
Small, parachute-shaped trees or shrubs 3-4 m high with a dense domed canopy, branching near the ground or a single trunk for more or less 1 m before dividing into a number of ascending branches which terminate with drooping branchlets; branchlets reddish and slightly angular.

Phyllodes linear lanceolate, 5-14 cm long, 2-5 mm broad, falcate, narrowed towards the base, glabrous and shiny when fresh, central vein prominent, lateral veins obscure, apex tapered into a short curved mucro; glands small on upper margin at least 15 mm above the base. Inflorescences axillary, solitary, mostly in racemes much shorter than the phyllodes consisting of 4-10 heads; flower-heads small, yellow, c. 40-flowered; peduncles hoary, 7-10 mm long; flowers 5-merous.

Legumes linear, 7-12 cm long, 4-5 mm broad, straight or curved, moniliform, smooth, brown. Seeds longitudinal in legume ovoid-obloid; funicle slender, reddish in a double fold 1/2-3/4 encircling the seed, gradually thickening into a fleshy aril.

Distribution:  Endemic to S.Aust., confined to the Flinders Ranges (northern part) region, growing in a tall shrubland on ridges and rocky shaly hillsides or along watercourses. Soils; shallow calcareous loamy. Rainfall 150-300 mm. S.Aust.: LE, GT, FR, EA. Flowering time: May — November. Flowers and mature pods often found on the tree together.

SA Distribution Map based on current data relating to specimens held in the State Herbarium of South Australia

Biology: No text

Related taxa: Acacia calamifolia (sp. 21) differs in its solitary heads or very few flowered racemes and a small gland situated near base. A. araneosa is related in flower, and legume characters but differs in its long terete phyllodes.

Taxonomic notes: The only mistletoe so far found on Acacia rivalis has been two collections of Amyema preissii, wiry mistletoe.

Cultivation: Silver wattle has an attractive habit with drooping branchlets and shiny phyllodes. This species should be considered for ornamental, park and dry country planting; moderate to fast growth rate. It was of commercial value for a number of years in the early 1900's for the 'Silver Wattle' gum which was a small and little known industry. The gum was collected by the local people in Blinman and the near surrounding area and sent to Adelaide.

Author: Not yet available

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