Blue Stars, Aristea ecklonii — a potentially disastrous weed found at Springbrook

Aristea ecklonii, Blue Stars, is a member of the Iris family. It is a potentially disastrous weed, introduced into Australia from Africa. It remains available for sale from nurseries because no government has yet listed it as a pest plant.

Outbreaks in Victoria and around Sydney are causing concern to local authorities.

It was first recorded in Queensland by ARCS President Aila Keto who found it growing on one of the Springbrook properties purchased by the Queensland Government, ‘Warblers in the Mist’.

Apparently established as a garden plant, it has spread across the majority of the 3-hectare property.

It produces masses of seed that are spread by overland water flow, wind, machinery or on boots of walkers. Isolated occurrences suggest that it may also be spread by animals either ingesting the fruits or catching seeds on their feathers or fur.

It can grow in the shade and has the potential to produce a dense ground cover under native forest or shrubland thus preventing regeneration of the native plants. Thus it belongs to a new dangerous class of shade-tolerant invasive species

Aristea produces rhizomes (underground stems) that help the plant survive adverse conditions. These rhizomes produce new shoots when conditions are favourable. It can also produce a dense mat of fine fibrous roots.

Aristea ecklonii is susceptible to glyphosate but indications are that the rhizome is not killed and resprouting from the rhizome occurs.

Experiments are underway using different concentrations of glyphosate with and without metsulfuran methyl and using different application methods.

Digging up plants, making sure to remove all of the rhizome, is effective but time-consuming.

As an interim control measure, teams of volunteers remove flowers and fruits between Spring and Autumn before fruits open.

Volunteers digging up aristea

Dense fibrous root mass on Aristea ecklonii

Aristea can be seen extending into shaded areas within the forest

Intensive growth of aristea under a thicket of leptospermum

Aristea 1 week after spraying with glyphosate

Aristea 5 weeks after spraying with glyphosate

A “lawn” of Aristea ecklonii on the Springbrook property, ‘Warblers in the Mist’
Aristea ecklonii flower (Blue Stars)

Fruits of Aristea ecklonii showing seeds which are
about 1 mm diameter. One plant could produce
more than 5000 seeds in one fruiting.
Rhizome of Aristea ecklonii