Willows

Where did willows come from?

They were introduced by European settlers in the 1860s.

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Are all the willows the same?

Willows are part of the genus Salix, whjch belongs to the family Salicacae. There are some 300 species and varieties, none of which are native to Australia.
Over 100 of these species and varieties have been introduced to Australia and are now a major pest of waterways.

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How do willows spread?

The willow species in SA reproduce asexually meaning they don’t need female and male plant to reproduce. Broken-off branches and twigs take root and soon a whole new plant establishes itself. Since they take root so easily, they quickly colonise and spread.

Some willows produce suckers that may separate into clones – allowing one tree to become many.

Willows do however, reproduce sexually if there are male and female plants present.

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Who introduced willows and when?

Willows were introduced by European settlers. They were planted to assist with navigation along the River Murray during the riverboat trade. Other reasons for their introduction have been associated with their aesthetic appearance to Europeans.

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Why are willows a problem?

The Australian ecosystem has not evolved with them. They affect both the diversity of native species that can live alongside them and the numbers in these wildlife populations.

They cast heavy shade which doesn’t allow light to get to other plants, so the banks are often bare and there is no understorey to provide food and shelter for wildlife.

Willows are deciduous and drop their leaves at one time in autumn. The leaves then reach the River and release large amounts of nutrients in a short time.

Willow branches fall into the River and rot quickly, not allowing for the establishment of a habitat for aquatic animals like native tree species. Their deep roots slow water movement, which encourages sedimentation.

Willow bark is too dense to create hiding places for insects, therefore do not provide many native animals, birds and insects with either shelter or food.

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Why don’t we remove them?

The removal of willows is a contentious issue. The sheer cost and effort involved in removing willows means that it is not practical to take more than a few out.
Removing willows without replacing the area with native vegetation can cause bank erosion, which is another issue that is faced when removing them.

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Are willows along the whole River Murray?

Yes.

However, they are more of a major weed problem in SA, especially between Wellington and Mannum.

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What can I do?

- Pull out shoots to control their spread.
- Be careful of spreading twig litter from willows – it can reshoot
- Don’t plant willows near the River Murray – use local native species like native willow or river coobah, bottlebrush, bulrushes, reeds or sedges.

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Information

Information sheets

Murray-Darling Association

What’s What about Willows and the River Murray, Fact Sheet 2,

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