Another wattle ‘problem’

Late winter throughout the Goldfields country is always brightened up by an explosion of yellow. At the moment a number of local wattles are looking great – Golden, Silver, Rough and Spreading Wattles are all flowering. A walk along the Loddon at Newstead will reveal another wattle flowering, this time not quite so desirable. Green (or Early Black) Wattle Acacia decurrens is a native of eastern New South Wales but has been widely used in revegetation programs outside its natural distribution, often mistakenly in place of Black Wattle Acacia mearnsii.

Green Wattle, Loddon River @ Newstead, 13th August 2012.

Black Wattle is indigenous to the Newstead area and flowers later in the season than Green Wattle. They can easily be distinguished by examining their ‘leaves’, actually phyllodes - flattened leaf-like structures, rather than true leaves. The phyllodes of Green Wattle have a single gland at the point where they divide into pinnae, whereas in Black Wattle there are usually two glands between the pairs of pinnae.

Green Wattle phyllode - note the single gland at the base of the divided pinnae.

Black Wattle – note the multiple glands.

Like Cootamundra Wattle [see post], Early Black Wattle has not yet become a rampant problem weed in our area, although unfortunately this has not been the case in parts of SW Western Australia and a number of places overseas where it is a major concern. It demonstrates the importance of taking care when selecting species for revegetation.

Green (flowering at left) and Black Wattles on the banks of the Loddon River @ Newstead, 13th August 2012.

Erratum: Thanks to one of our correspondents, Mel, for correctly pointing out that the feathery pinnae of both wattles are in fact true leaves. They are attached to the phyllodes, where the glands reside, in both Green and Black Wattles.

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3 responses to “Another wattle ‘problem’

  1. Geoff, I think the bipinnate leaves on Acacia decurrens are true leaves. A. decurrens is one of only a dozen or so Australian wattles that doesn’t lose its juvenile leaves and form cladodes or phyllodes.

  2. Thanks for the article. This has helped us identify some wattles next to the newly opened National Aboretum in Canberra (on the zoo side of the parkway).
    More importantly, it helped me win the argument that the grove of wattle we stumbled upon was a native species, not from Africa. :)

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