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The Cootamundra Wattle ( baileyana) is immediately recognisable by its elegant, feathery, silver foliage and clusters of golden yellow flowers. This lovely (sometimes small ) comes from a relatively small area of the Central Western and South Western Slopes of New South Wales1. As the common name suggests, its home territory is Cootamundra where it has been adopted as the emblem of the Cootamundra Shire Council. It has long been a favourite with gardeners; however, it hybridises with numerous other Acacia species and has spread rapidly, not just throughout Australia but also throughout the world2. If you live close to bushland, this is one species you should avoid planting.

Natural distribution of Cootamundra Current world distribution of Wattle (Acacia baileyana) Cootamundra Wattle (Acacia baileyana)

Acacia species have two very different types of “leaves”. The feathery leaves of the Cootamundra Wattle are true leaves and are referred to as “bipinnate” leaves, because each leaf is twice divided (ie twice pinnate) with the final product tiny leaflets (or pinnules).

Acacia baileyana – true, bipinnate leaves

The so-called “simple” leaves of other Acacia species, such as the Queensland Wattle (Acacia podalyriifolia) are actually phyllodes, flattened leaf stalks (petioles) which function as leaves. Queensland Wattle – leaves are actually phyllodes (flattened petioles or leaf stalks)

Extrafloral nectaries (glands) on the phyllode s of Queensland Wattle…… and along the mid-rib of this bipinnate wattle leaf.

The common factor in both bipinnate leaves and phyllodes are glands, or extrafloral nectaries that can be found along the mid-rib of bipinnate leaves and on the margin of phyllodes. Extrafloral nectaries are sugar-producing glands that have no connection with flowers, but may be present on leaf mid ribs, petioles or on leaf margins. It is thought that they developed from trichomes (fine outgrowths) which tap sugars carried in the phloem3. The nectar produced by the extrafloral nectaries attracts ants which can play a defensive role in protecting the plant. Birds, too, are sometimes attracted to the nectar from these glands.

1 Plantnet: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Acacia~baileyana 2 Wikipedia: http://en.wikipedia.org/wiki/File:Acacia-baileyana-range-map.png 3Wikipedia: http://en.wikipedia.org/wiki/Nectar Map of natural distribution: Modified from Australian Native Plant Society, http://anpsa.org.au/a-bai.html Map of world distribution: Modified from Wikipedia, http://en.wikipedia.org/wiki/File:Acacia-baileyana-range-map.png

Text and photographs: Alison Downing & Kevin Downing Downing Herbarium, Department of Biological Sciences, 16.07.2012