21 April 2013

A "grasstree"

Found only in Australia, all 28 species of grass trees are perennial, slow-growing plants belonging to the ancient genus Xanthorrhoea. Some species produce aboveground trunks, while others do not. A grass tree’s trunk is a cylinder formed from tightly packed leaf bases... The leaves of grass trees with trunks obtain water and nutrients via aerial roots that pass down through the open core of the trunk to the ground... Bushfires blacken the trunks of grass trees, but don’t kill the plants. Like many species of eucalyptus trees, grass trees possess highly resinous leaves and exist in an intimate relationship with fire, depending on it for their survival. Flowering is stimulated by fire.
Image (of a tree with some carving of the "trunk") credit © Vilis Nams, via The Seeker, Magi Nams and The Soul is Bone.


  1. As they grow incredibly slowly, depending on sub-species, some of them are very old:
    "a five-metre-tall member of the fastest growing Xanthorrhoea may be 200 years old, a member of a more slowly-growing species of equal height may have aged to 600 years".
    The common name, for a while, was "Blackboy", which is now for the most part considered culturally offensive.
    It's a very interesting tree. One of my neighbours grows them: http://www.facebook.com/grasstrees

    1. From your neighbor's page, it appears that "grasstree" is conventionally written as one word. I've revised the title of my post. Tx.

      And I'm surprised that the root system for such a bulky plant can fit into such a small pot. I would have thought that in your semi-arid region the plants would have wider root systems or a deep taproot. Interesting.

    2. Thanks for getting there before me Dr Mieke. I was about to post to say that growing up in WA, we always knew them as "blackboys" - I didn't know that wasn't the name that's used these days!

  2. Thick 'bark' + really really thin leaves = very very little moisture loss through evapotranspiration.

    There are other ways they cope, too: see http://www.environorth.org.au/windows/all/allconserving_moisture.html

    Many Australian trees have very thin leaves. The early (British) landscape artists wanting to paint the Australian landscape had trouble accurately depicting the pattern of light and dark, and their initial paintings resembled English forests. It took some time before they became used to the more open foliage. One of the good early artists who paved the way was John Glover. See http://en.wikipedia.org/wiki/John_Glover_%28artist%29


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