Cestrum

There are a few different Cestrum species occurring in our region. Green Cestrum (Cestrum parqui) is listed in the Queensland Biosecurity Act 2014 as an invasive plant, although it is not a prohibited or restricted species. Night Jessamine (Cestrum nocturnum) is very similar, although not listed as an invasive species – I’ll treat them as the same for this discussion.. I think that we mainly have Night Jessamine at Crystal Waters and, although it’s not listed either in Qld or by Sunshine Coast Council, I consider it a problematic weed here. It has all the worst features of Green Cestrum: it spreads readily by seed and suckers, is invasive and smothers native vegetation, and is highly toxic to both stock and humans. Even the dead leaves and stems are toxic. Some people like the smell and many people have it in their gardens – but it has spread from gardens to many places on our common land, by bird dispersal and possibly through dumping of cuttings (which regrow very readily). It doesn’t appear in the Sunshine Coast Council’s Biosecurity Plan 2024 (which you can find here), but I treat it as a “locally significant species”, with the aim of controlling and preventing its’ spread when it is impacting or threatening high value natural areas. More information on it can be found here.

Information and Identification

Green Cestrum comes from South America, while Night Jessamine comes from Central America. They are in the Solanum family, which includes tomatoes and potatoes as well as a wide range of very toxic plants such as deadly nightshade. They have become invasive in parts of NSW and Qld, as well as in New Zealand and some Pacific Islands.

Identification:

• Scrambling shrub up to about 4m tall.
• Shiny green leaves with distinct veins and a very unpleasant smell when crushed.
• Whiteish or greenish to yellowish long tubular flowers in clusters at the tops/ends of the stems.
• Small berries starting green and turning purplish black (green cestrum) or whiteish (night jessamine) when ripe.
• Multi-stemmed.

Impacts

• Can form dense thickets which outcompete native vegetation and prevent regeneration of native species.
• Highly toxic to stock and humans. Gloves and protective clothing should be worn when handling it.

Distribution at Crystal Waters

Mostly in wetter gullies, riparian areas and in and near gardens.

Control methods and efforts

Over the years we have worked on reducing this weed in riparian areas, however, I’m always finding new ones – probably spread from people’s gardens. Cutting and dabbing with Glyphosate reduces them, but a few treatments are usually needed to kill them. Disturbance by cutting or digging just causes them to sucker prolifically! When I went out to take the photos for this post, I discovered that it’s made quite a comeback in the gully below our lot – we had worked on it extensively 10 or so years ago, but obviously didn’t eliminate it – all control efforts need follow-up! Given how readily it spreads and how hard it is to get rid of, it would be good if more lotowners took responsibility for the cestrum growing on their own lots.