Hakea salicifolia in the EPPO region: addition to the EPPO Alert List
Why
Hakea salicifolia (Proteaceae) originates from Australia and has been introduced into the EPPO region for ornamental purposes. This species has escaped cultivation in parts of the Mediterranean region and shows invasive behaviour. The EPPO Panel on Invasive Alien Plants are seeking further information on any additional occurrences of H. salicifolia in the EPPO region and reports of environmental and economic impacts.
Geographical distribution
EPPO region: France, Portugal, Spain.
Africa: South Africa.
Oceania: Australia (New South Wales (native), Queensland (native), South Australia, Tasmania, Victoria), New Zealand.
Morphology
Hakea salicifolia is an erect shrub or small tree 3–5 m high. Branchlets with several prominent longitudinal ribs, and glabrous. Leaves narrowly elliptic, 8–15 cm long, 4–17 (–27) mm wide, narrowly attenuate, usually acute or acuminate. Inflorescence a single umbel of 16–28 white flowers in upper axils, pedicels 4.5–7 mm long. Fruit obliquely ovate, 2.3–3.5 cm long, 1.3–2.3 (–3) cm wide Seed 17–20 mm long.
Biology and Ecology
Hakea salicifolia produces wind dispersed seed that are released from an aerial seed bank after fire, though some seed are released continuously from the canopy. Regeneration can also occur from stumps.
Habitats
In the invasive range, H. salicifolia can invade grassland, wooded habitats, ruderal habitats (including roadsides and urban areas).
Pathways for movement
Plants for planting. H. salicifolia has entered the EPPO region as a horticultural ornamental species. It has also been planted as a wind break and a hedge plant.
Impacts
Hakea salicifolia can form dense monospecific stands which can act as an ecosystem transformer. Dense populations can outcompete native biodiversity and have negative impacts on ecosystem services. Hakea salicifolia populations can increase the risk of fires and increase fire intensity.
Control
Control is difficult and costly. Control methods can include a combination of mechanical and chemical control options. Shrubs can be cut and herbicide application to cut stumps can be applied.
Sources
Invasoras.pt (2024) Hakea salicifolia. Available at: https://invasoras.pt/en/invasive-plant/hakea-salicifolia
van Valkenburg JLCH, Beyer J, Champion P, Coetzee J, Diadema K, Kritzinger-Klopper S, Marchante E, Piet L, Richardson DM, Schönberger I (2024) Naturalised Hakea. What species are we actually talking about in Europe? Botany Letters 171(3), 357-370. https://doi.org/10.1080/23818107.2024.2318761
USDA (2013) Weed risk assessment for Hakea salicifolia (Vent.) B. L. Burtt. (Proteaceae) – finger hakea. Available at: https://www.aphis.usda.gov/media/document/85767/file
Williams PA (1992) Hakea salicifolia: Biology and role in succession in Abel Tasman National Park, New Zealand. Journal of the Royal Society of New Zealand 22, 1-18.