Vassal’s Wattle (Acacia vassalii) is listed as Endangered under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), and Critically Endangered under the WA Biodiversity Conservation Act 2016.
Vassal’s Wattle is a semi-prostrate shrub usually growing from 0.3–0.6m high. In open areas, it forms a dense cushion up to 1m in diameter, and in shaded situations, it is more diffuse and upright. The “leaves” are phyllodinous (i.e., comprised of flattened leaf petioles), and are straight or slightly S-shaped, 4−8mm long by 1mm wide with hooked tips. The flowers are light-golden in colour, and arranged in globular heads, one per leaf axil. Each flower head is about 4mm wide, on a stalk of about 5mm long, and flowering occurs from June to August. Pods are about 2cm long by 1–1.5 mm wide.
Vassal’s Wattle is known from three main areas – near Wongan Hills, Moora, and two populations north-east of Watheroo. Each area consists of a number of smaller sub-populations spread over a total approximate range of 85km. Vassal’s Wattle is found on greyish brown or yellow sand, or sandy loam, in low scrub and heath.
The main threats to Vassal’s Wattle future survival are the small number of individuals currently known, and the species’ limited geographic range. The small numbers of individuals in many of the known populations leave these populations vulnerable to extinction through stochastic events. A decline has been recorded in at least one population in the Wongan Hills area, and surveys have failed to rediscover previously known populations in the Moora area. Additionally, most plants are in rail or road reserves, and none are currently recorded from conservation reserves. Lack of appropriate disturbance regimes and intervals is another identified threat to Vassal’s Wattle. This species of Wattle is also potentially threatened by weed invasion, particularly in disturbed roadside areas. However, plants in open areas and disturbed roadsides appeared healthier than those in more established vegetation communities and shaded areas, indicating that this species is likely a disturbance opportunist.
Information Source: Government of Australia, Department of Environment and Energy; and WA Department of Biodiversity, Conservation and Attractions (FloraBase).