Shade Loving Weeds and Revegetation

Re-vegetation with native species can be a great way to enhance the local environment, provide habitat for local wildlife and also shade out weeds such as Blackberries and Ragwort. One thing to be aware of is that some weeds thrive in shady conditions and if left unchecked can rapidly take over and smother and kill any of your new plantings and provide no chance for other native species to naturally regenerate. Weeds that already exist in the area and that thrive under canopy shade include Blue Periwinkle (Vinca Major), Arum Lily (Zantedeschia aethiopica) and Wandering Creeper (Tradescantia fluminensis). A major priority of any project, where shady conditions exist or will be created, should be to control these weeds if they are present. If you are planning re-vegetation these weeds should be eliminated from a site before you start any planting.

Blue Periwinkle has taken over the understorey under the canopy of these trees at this site in Traralgon South.

Close up of this site showing Zantedeschia aethiopica (Arum Lily) and Vinca major (Blue Periwinkle) providing no chance for indigenous understorey.

The genus name Vinca is derived from a latin term meaning “I conquer” this refers to its abilty to smother other plants. It is an escapee from gardens and reaches more remote areas of bushland via people dumping garden waste in forests and along roadsides. It can reproduce vegetatively therefore plant fragments caught in machinery or washed in floods can also enable its spread.  It has distinctive blue flowers and broad glossy leaves that are arranged in opposite pairs. Small plants may be able to be dug out, but all the roots need to be removed or it will re-sprout. Use of an appropriate herbicide while the plant is actively growing is the main control method.

Vinca major – Blue Periwinkle, in flower.
Vinca major – Blue Periwinkle , showing its paired shiny green leaves.

Arum Lily is another shade loving garden escape weed that is making serious in-roads into the local area displacing the local flora. It is considered extremely poisonous to all animals, (I should know after tasting some and being violently ill when I was a child). It can spread via suckering and seed which can be carried by birds, foxes, floods, dumped soil and garden waste. Its appearance will be first noted by the sprouting of its large rubbery,arrow headed shaped leaves and then its distinctive white flowers. Once again if controlling by hand all of the roots need to be removed from the soil. Herbicide is the most common control method for larger infestations. Remove the flowers to prevent the spread of seed.

Zantedeschia aethiopica – Arum Lily – Flowers
Zantedeschia aethiopica – Arum Lily – Rubbery Leaves

Wandering Creeper (Tradescantia fluminensis) is a weed that has been well known as a pest in bushland for a long time now and it forms a thick creeping carpet that once again smothers indigenous plants and prevents new ones from germinating, it is also very toxic to cattle. It spreads by stem fragments being dispersed often by garden waste dumping and machinery. Hand weeding is possible but labour intensive because of the need to remove all roots and plant material to prevent regrowth. There are several herbicides that are registered to control this weed.

Tradescantia fluminensis – Wandering Creeper, in flower
Tradescantia fluminensis – Wandering Creeper, forms a thick mat of weed smothering native species.

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