Dyschoriste depressa

Dyschoriste depressa is a recognised weed at Crystal Waters but does not appear in either the State listing of Invasive Plants or the Sunshine Coast Council’s list of priority invasive plants in the newly released Biosecurity Plan 2024 (which you can find here). Further information on the species can be found here. I am including it here as a weed of the month since there has been quite a bit of discussion about it.

Information and Identification

Dyschoriste depressa is originally from the floodplains of southern Africa and is only recently naturalised in Queensland, having been first reported from the suburbs of Brisbane in 2000. It spreads by seeds and plant fragments, carried by water, animals, humans and machinery. It is recognised as a particular problem in riparian areas, but it’s clearly quite happy away from riparian zones, given what we’ve observed here at Crystal Waters. It can form a dense monoculture, excluding all other native ground cover species and probably preventing regeneration of larger species.

Identification:

• It grows either as a prostrate ground cover (where it is mown) or as a small upright scrambling herbaceous plant to about 60cm tall.
• The stems are squarish in cross-section and form roots at the nodes in contact with the ground.
• The leaves are bright green with distinctive veins and occur in pairs along the stems.
• The pale pink or white flowers are tiny and almost stalkless, developing in the leaf forks in clusters.
• The fruit are inconspicuous but explosive! (but not deadly – the explosions are very small!). This is a mechanism for dispersing the seeds.

Impacts

Environmental

• Potential to damage riparian ecosystems and reduce biodiversity and may also restrict the flow of water.

Distribution at Crystal Waters

This plant is extremely widespread. The densest infestations are probably around Lots 39-55, but I have found it pretty much everywhere I’ve been. Despite being recognised as a particular problem in riparian areas, so far it is not that common in our riparian zones. It is clearly spread by mowing and probably walkers as well, but it must also be spread by animals such as kangaroos and wallabies, as I have found it in quite remote areas where machinery cannot reach and very few walkers go.

Control methods and efforts

A few people have tried to eliminate the weed from their own lots and small infestations on common land, however I don’t think there has been much success. With the plants spreading both by fragments and seeds, in combination with the dense root mats formed, they are very difficult to remove completely. Any small fragments left will regrow. I suggest that everyone ensures it does not become established in their vegetable growing areas, as I think it would quickly smother anything. Without chemical control I don’t believe there is any way we can control this weed on the common land. Its latin name is very apt: depressing!