Green Cestrum (Cestrum parqui) – Weeds of Melbourne

Green Cestrum (Cestrum parqui), a toxic South American ornamental shrub that became a notorious killer of cattle in eastern Australia. Its seed is bird-distributed and the perennial rootstock is very difficult to remove, with suckers reemerging through successive years of surface management.

The plant arrived from Chile into the hands of English gardeners by 1787 according to Loudon. However, unlike other Cestrums there is little evidence that this one was a Victorian-era introduction into Australia; among the first records I can find is a cultivated plant at the RBG-Melbourne in 1912.

Green Cestrum appears to have become established around Brisbane by the early 1920s, when it was recorded growing naturalised at the city’s botanic gardens and at Redland, Ashgrove and Kangaroo Point. By 1928, the species had been blamed for livestock deaths on Brisbane’s southern outskirts, and in 1933 it was declared a noxious weed throughout Queensland. On the east coast it had become known as ‘Wild Peach’, presumably for its general resemblance in leaf; others plants known by this appellation include the northern Australian native Trema tomentosa.

The species was establishing simultaneously in NSW (where it was picked up in the early 1930s), SA (1939) and Victoria, where it was collected in the King River Valley in 1938 and 1940. Losses of cattle, sometimes heavy, continued in QLD and NSW through the 1940s and 1950s and indeed to the present day; a 2012 article in The Land newspaper describes annual winter losses from Green Cestrum on NSW’s North West Slopes region.

Within metropolitan Melbourne the plant was recorded in the Yarra and Dandenong Ranges in 1980 and at a handful of more suburban sites subsequently. In comparison to the east coast, Green Cestrum appears to remain relatively rare in Victoria outside of longstanding infestations on the King River and the Mitchell River. Although usually associated with moist areas, the two occurrences shown here were found beneath mature Peppercorn trees on railway embankments in Fitzroy North and Richmond.