Portraits of Wildflowers

Perspectives on Nature Photography

Another side to Silphium radula

with 35 comments

Orange Under Silphium radula Leaf 6199

When I photographed some roughstem rosinweed, Silphium radula, along Bull Creek on July 7th, I noticed that the underside of one leaf looked unusually and strangely colorful, as you see here. I don’t know what these orange flecks were, perhaps something to do with a fungus or aphids; if anyone can say, please speak up. Whatever it is, I like the abstract combination of orange and green and rough texture.

© 2014 Steven Schwartzman

Written by Steve Schwartzman

September 3, 2014 at 5:45 AM

35 Responses

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  1. That is a really interesting capture, but I have no idea what the orange flecks are. At first glance I thought I was looking at a field of orange flowers :).


    September 3, 2014 at 5:49 AM

    • Me too! I thought Steve had managed to get a bird’s eye view of a field of Silphium radula.


      September 3, 2014 at 6:48 AM

      • Great minds think alike :).


        September 3, 2014 at 6:56 AM

      • This is one case where reality trumped imagination. Having been there and taken the picture, I knew that what you’re looking at here was only a few inches across, so I never thought about the big change in scale that would have turned this into an aerial view of the earth below. I’m glad the two of you saw it that way.

        Steve Schwartzman

        September 3, 2014 at 7:36 AM

    • For once our roles are reversed, Cindy. It’s not even Friday but I’ve got you guessing what some strange thing is. (Readers, check out Cindy’s blog and you’ll see that as of last week she was up to Mystery Photo #143—a number, I’ll add, that’s divisible by 11 and is also the product of two consecutive primes.)

      Steve Schwartzman

      September 3, 2014 at 7:26 AM

  2. WOW! Love this.


    September 3, 2014 at 5:50 AM

    • Here you’ve got the leaf, if not the twig. (Readers, see seedbud’s blog and you’ll understand.)

      Steve Schwartzman

      September 3, 2014 at 7:50 AM

  3. Hmmm. As Loony said. . I thought I was looking at a field of flowers!
    Maybe a rust, which is a fungus. That is my guess wo research.

    Midwestern Plant Girl

    September 3, 2014 at 6:13 AM

    • It’s certainly a rusty color. I’d say I’m rusty when it comes to rusts except I can’t have forgotten what I never knew.

      Steve Schwartzman

      September 3, 2014 at 7:53 AM

  4. I am pretty sure you are seeing Oleander Aphids, Steve. I see them on milkweed quite often.
    Nice detail leaf and pest abstract.

    Steve Gingold

    September 3, 2014 at 6:56 AM

  5. Clearly, your soupy, goopy, cheddar-on-toast puddle water has transmogrified itself, time-traveled, and landed on this leaf. That’s my story, and I’m sticking to it.


    September 3, 2014 at 7:15 AM

  6. I thought it was lichens until I read the post. Could it be a form of rust? I like the colour and texture.


    September 3, 2014 at 10:17 AM

    • Rust was one suggestion, Jude. I wish I knew for sure, but regardless of identification I’m with you in loving the color and texture.

      Steve Schwartzman

      September 3, 2014 at 12:03 PM

  7. Love it!


    September 3, 2014 at 11:15 AM

  8. It’s certainly a mystery, and I’m looking forward to your final verdict. I suppose it’s not easy to send one to your local university extension service for an identification…we have a Backyard Farmer program put on by the U of NE Lincoln, manned by folks who are very happy to answer such questions from listeners. You could always just send a photo rather than an actual sample.


    September 3, 2014 at 12:45 PM

  9. I’ll have to agree with Heyjude that this looks too two dimensional to be an aphid, and that it looks more like plain-old leaf rust to me … but perhaps we need a bit more magnification for a definitive diagnosis! On an unrelated matter, the species name of Silphium caught my attention, right away. ‘Radula.’ Did you know that a radula, in zoological terms, is a toothed membrane that most gastropod molluscs use to scrape the substrate for their food? Herbivorous snails use the radula to gather bacterial films, or diatoms, or filamentous algae from the substrate. The wonderful German term Aufwuchs nicely describes this living film upon which these molluscan grazers feast. Anyway, the radula is manipulated over a bit of cartilage (the odontophore) by a series of minute muscles to achieve the movements of feeding. The rasp then delivers a fine stream of food to the esophagus, and so on. I wonder why the term is applied here to a plant?

    As the kids would say … check this out (I hope the link works).

    Pairodox Farm

    September 3, 2014 at 6:21 PM

    • We’ll tally your vote in favor of rust.

      Latin rādula meant ‘scraper’, which accords with that you’ve described in zoology. Botanists seem to have borrowed the term as the name for this species because of the plant’s ‘scraperness,’ i.e. roughness. The Latin verb rādere ‘to scrape’, specifically its past participle rāsus, is ultimately the source of our verb raze and our noun razor.

      That’s one mean-looking mollusk mouth in the video. Don’t think I’d want it to scrape my skin.

      Steve Schwartzman

      September 3, 2014 at 6:39 PM

      • Yup .. it’s interesting that the poison dart of the cone shell forms from a number of fused radula teeth … these are homologous structures. [Another word that I love.] Thanks for the origin of ‘radula’ … although it was one topic of my doctoral work (the biomechanics of the thing, that is) I did not know, until now, the latin origins of the term. Thanks. It is true what they say … you learn something every day. D

        Pairodox Farm

        September 3, 2014 at 7:01 PM

      • I prefer the term Scraperositudinousness. It’s so much more rambunctious. 😉


        September 8, 2014 at 3:42 PM

  10. The image brings to mind the acres and miles/kilometers of sunflower fields around us as we bused from Budapest to Vienna to Prague. Cool shot of intriguing whatever-it-is!


    September 8, 2014 at 3:44 PM

    • We never did get the whatever-it-is resolved, but by any name (or lack of a name) it’s just as strange. I can see why it would remind you of acres of sunflowers in central Europe, but I can’t see why you didn’t invite me along as your official expedition photographer.

      Steve Schwartzman

      September 8, 2014 at 4:03 PM

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