Acacia lasiocalyx, commonly known as silver wattle and known by the Noongar peoples as wilyurwur, is a species of flowering plant in the family Fabaceae and is endemic to the south-west of Western Australia. It is an open, often weeping, glabrous shrub, or sometimes a tree, with pendent, linear, leathery, more or less straight to curved phyllodes, spikes of densely arranged golden yellow flowers, and linear pods raised over the seeds and constricted between them.
Description Acacia lasiocalyx is an open, often weeping, glabrous shrub that typically grows to a height of , sometimes a tree up to , its branchlets covered with a white, powdery bloom. Its phyllodes are leathery, linear, straight to curved, long, wide, the tips obviously curved, and finely striated with the midrib being the most prominent. The flowers are borne in spikes on paired peduncles long and covered with a powdery bloom, the spikes long and wide, with densely arranged golden yellow flowers. Flowering occurs from July to October, and the pods are linear, leathery, up to long, wide, straight to slightly curved and raised over the seeds and constricted between them. The seeds are elliptic, long and glossy dark brown.
Taxonomy Acacia lasiocalyx was first formally described in 1904 by Cecil Rollo Payton Andrews in the Journal of the Western Australian Natural History Society from specimens he found on sand plains near the Gairdner and "Hammersley" Rivers in 1903. The specific epithet (lasiocalyx) means 'shaggy or woolly sepals'.
Distribution and habitat This species of wattle grows in gravelly, loamy or clayey sand and loam, often on the slopes of granitic hills and granite outcrop, but also on sandplains and in mallee woodland and heath and is widespread on the southwest of Western Australia from near Eneabba and Kalgoorlie and south to Bremer Bay and Mount Heywood north-east of Esperance, in the Avon Wheatbelt, Coolgardie, Esperance Plains, Geraldton Sandplains, Jarrah Forest, Mallee, Murchison and Swan Coastal Plain bioregions.
Ecology The tree is fibrous and copes well in arid conditions. It germinates prolifically after fire forming dense thickets of trees which are about in height. These thickets thin out over the following decades, and trees my attain a height of 25 metres.
See also List of Acacia species
References