#ThreatenedSpecies of the Week: Johnson’s Mallee (Eucalyptus johnsoniana)

Johnson’s Mallee (Eucalyptus johnsonia) is listed as Vulnerable under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and under the WA Biodiversity Conservation Act 2016.
Photo credit: Florabase

Johnson’s Mallee (Eucalyptus johnsoniana) belongs to the family Myrtaceae and is a small spreading mallee growing up to 2 m tall, forming dense clumps that may be several metres across. Their dense crowns of glossy, dark green to blue-green leaves often extend to the ground. The bark is smooth and grey-brown to cream above, but grey-brown and slightly rough and flaky at the base. The leaves are narrow, lanceolate, grow to 12 cm long and have numerous oil glands. There are seven flowers in each unbranched, axillary inflorescence. Club-like and pear-shaped buds have a hemispherical to slightly conical cap. Fruit are globular, approximately 1 cm in diameter, and have a small opening and a thick rim. The sunken disc has 3–4 valves, which may protrude slightly. Seeds are pyramid-shaped and brown, and flowering occurs from July to January.

Johnson’s Mallee (Eucalyptus johnsoniana) is endemic to Western Australia where it is known from 34 populations between Eneabba and Badgingarra. The total population size is estimated to be 360 plants occurring over approximately 330 km2. The majority of populations are in healthy condition and it is likely that these populations will increase in the future; however, fire and mining may cause a rapid decrease in the number of populations.

Small populations or isolated plants emerge from low, dense heath on undulating sandplains, lateritic mesas and uplands in white or grey sand over laterite. Johnson’s Mallee (Eucalyptus johnsoniana) grows in association with certain species such as Coastal Blackbutt (E. todtiana), Drummond’s Gum (E. drummondii), Badgingarra Mallee (E. pendens), Prickly Dryandra (Banksia armata), Shell-leaved Hakea (Hakea conchifolia), Dwarf Sheoak (Allocasuarina humilis) and Xanthorrhoea species.

The main potential threats to the species include fire, clearing, transmission line maintenance, human disturbance and mining. Johnson’s Mallee (Eucalyptus johnsoniana) is presumed vulnerable to fire in the vegetative and flowering phase, and too frequent fire may deplete the soil seed bank. Clearing associated with firebreak, road and transmission line maintenance, and agriculture may adversely affect this species.

 

Information Source: Government of Australia, Department of Environment and Energy and Department of Biodiversity, Conservation and Attractions, and Florabase.

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