Sunday, June 22, 2008

Very pretty, but what is it?

Except in the section of the WhiteRock beach nearest the pier, access is problematic. If the obstacle is not a high cliff face or a muddy slough, the way is blocked by thickets of thorny shrubs, the invasive blackberry or native wild roses. Friday, we followed a narrow path hacked through the roses.

On the beach side, many of the twigs wore a bright orange wrap.

Orange-peel bright, about the size of a small caterpillar, crusty and peeling back where the twigs exit. Here's another:

I cut a twig and turned it over. The bottom was dusted with orange specks and threads. The specks fell off easily; you can see some already on the log where I laid the twig to take a photo.

And do you see those little round bumps on the stem? Here they are, close up:

So is this a slime mold? It looks like it to me. But I can't find anything quite like it in my books, nor on the web. Google failed me, for once.

I have my little twig in an egg-cup full of water now. I'll be watching it for signs of growth, or colour changes as it ages.

And I'm hoping someone can help me with an ID. I'm stumped.


  1. Hi Weeta,

    From the general form and fruiting bodies, I would say that this is very likely to be a slime mold, not a fungus. My guess would be something in Physarum, possibly P. superbum or P. fulgens. The fruiting bodies in your photo are still very small; check them again in a day or two and see what they look like when mature. That will likely provide a diagnostic character.

  2. Thanks, Mike.

    I'll read up on Physarum while I wait.

  3. Very odd. I couldn't find a slime mold image that had that powdery texture; time will tell, but it looks more like a fungus to me. I googled "orange fungus on Rosa" and there were a few images of Phragmidium, a rust, that showed stem encasement, but nothing as robust as your mystery blob.

  4. Hugh,

    Thanks. I googled Pragmidium, and look what I found!

    a photo of the same thing, on another rose. (6th photo on the page.)

    And in a site from Argentina, there is a good photo of the dust on the underside of a leaf: here. A bit clumpier, but close enough.

    Weird. Because the fruiting bodies do look like a slime mold. Anyhow, a bit of aging should confirm the "diagnosis".

  5. I was going to suggest that it looked an awful lot like an active, orange version of the Black Knot I blogged about in the winter. Specifically, the one photo you have where it's actually bent the curve of the branch. It sounds like what Hugh said has pointed you in the right direction. :)

  6. I had something very similar here at Roundtop this spring--unfortunately I can't find the photo at the moment. Slime mold of some kind. I loved the color!

    Carolyn H.

  7. Seabrooke,

    Yes, I had noticed that bending on several of the branches of the shrub.

    You mentioned it looked like a gall. On the site where I found the photo of another infected rose, they call these "galls", too.


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