Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

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Is Retama raetam (Forsskal) Webb a legitimate alert list species?


Retama raetam (Forsskal) Webb (white weeping broom) is a leguminous shrub from the Mediterranean basin that was first recorded in Australia in the 1840s. It has a history as a garden plant, but has escaped and naturalised at several locations around Perth in Western Australia and in various locations in South Australia. R. raetam has been placed on the Australian National Environmental Alert List, a list designed for species that pose a significant biodiversity threat, but which are restricted in distribution making control feasible. Until now, there has been a scarcity of quantitative evidence to support the placement of R. raetam on the alert list. However, recent studies reported here demonstrate naturalised R. raetam has copious seed production, a high amount of seed dormancy and displays juvenile drought tolerance. These results along with the severity of a handful of current infestations suggest that R. raetam warrants control before eradication becomes infeasible.