The mat-forming Raoulia australis
Before I get into the details of this New Zealand native, a word about australis / australe since the word appeared yesterday as well. Contrary to what I’ve read on some nursery sites, this is not Latin for “of Australia”, but rather for “south”, as in the southern hemisphere. Aurora borealis–northern lights, Aurora australis–southern lights: that’s how I remember it.
To put this plant in context, you first need a few more facts than what this image can provide. Start by checking out this perspective image of Raoulia australis, which will give you an idea of just how small this vascular plant really is when you compare it to the nearby gravel. Second, you need to know that this plant is in the family Asteraceae. Third, you also need to know that the Asteraceae also includes sunflowers, which are perhaps two thousand times as high as this little mat-forming plant. For comparison’s sake, that’s roughly the difference between my height and the tallest building in the world doubled.
If you’re like me, you can only marvel, simply marvel, at the amazing diversity of forms and structures that have evolved.
So what are the ecological advantages of being low and small? In this case, I suspect it has to do with prevention of water loss. Raoulia australis, or scabweed, grows in dry, rocky areas of the South Island of New Zealand, ranging from high coastal elevations to alpine. Mat growth forms are ideal for water conservation: a low surface area prevents wind dessication; water requirements for nutrient transportation are low due to compact growth; and, in this case, water is “stored” in the peaty decaying layer of older leaves below the fresh growth instead of draining away into the rock or sand. In the perspective image, you can see a black fringe surrounding the mat, particularly the bottom left – these are exposed decaying leaves. It seems to me that this might be an indication that the plant is not doing well, and is contracting instead of expanding.
I only took this photograph at the prompting of Joe Keller from the Alpine Garden Club of BC, who said it would make a great “Stumper” for UBC’s online forums. The calibre of the people on the forums is just too good though, and it was answered by the second person to reply. Stumpers is a new forum where the most active forum members can challenge everyone’s plant knowledge by asking a plant-related question with only a few clues. Yes, we’re plant geeks, but it’s fun, and everyone can learn something.
Raoulia australis comes from the name of Etienne Fiacre Louis Raoul, a botanist born in 1815 in Brest. He extensively surveyed New Zealand in the 1840s, one of the last French to do so.
He’s got a memorial in Brest garden of explorators, and, having travelled to Tasmania and walked to Cape Raoul, I’m used to spotting his name (or his father’s who explored Tasmania) in geography or botany.
Hi, great site, is it possible to include full URLs in your links? The relative URLs don’t work in Bloglines.
Sophie, thanks for the extra comment.
Neil, thanks and done!
Its very use ful site for botanical students.
Any relationship to Wolffia? Also have
spectacular photos of flowering Lemna
persusilla, in November on L.I., New York.
Lance, the relationship to Wolffia is actually about as distant as can be between two flowering plants – but isn’t it interesting that the same sort of patterns emerge in “at a glance” appearances?
I do have to say, Wolffia is pretty cool.
That is really neat. I love that part of the world…..
Hello
Can you tell me where this plant is available?
I live in the Toronto area.
Thanks
Alison, that’s a better question for the (hidden until you register) Sourcing Plants and Supplies forum on the UBC Botanical Garden Forums.
This is just the perfect plant for a sandy, full sun area among the flagstones in my yard. Since it is a farily large area, I was hoping to find seeds. So far, I’m unable to find any. Any suggestions?
Sourcing is difficult – investigating alpine plant societies and participating in trading is one way, if you’re fortunate. You can also post on the Sourcing Plants forum (see link above “Post a Comment”)
just found this one at Home Depot
The way in which you have illustrated the size of patch plant in word and picture is striking.
The reason I am commenting (and congratulating you) however is because I may wish to ask your permission to use the photograph if it is still available in 12-18 months’ time. I am wrestling with the texts of many plants of R genera in preparation for adding them to my Master text, website and eventually the next edition of the CD. Although access to the website is free, the CD is not.
The reason for the hesitation is that until I have managed to complete a major part of the research and writing I cannot anticipate whether species from the Raoulia genus will be included. This is however a genuine request and I would be very glad to receive your approval. If you were to say ‘yes’ perhaps we could communicate by email (sue@plantlives.com).
Sue Eland