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Our next installment of What’s This? was growing in northern hardwoods on the way to the summit of Burnt Rock Mountain in Fayston, Vermont, on August 7, 2011. Name what you’re seeing here, including species, and win $5 off any of my outings or workshops.

Added May 17: Our winner this round is Sue Cloutier, who identified this as the underside of a Braun’s Holly Fern (Polystichum braunii) frond with its sori, those brown dots. Each one of those dots is a sorus (the singlular form of sori). And each sorus is a cluster of sporangia, little grape-like spheres that open to cast their spores to the summer winds. Honorable mentions go to everyone who recognized these as fern sori and to Sara Backer for yet another creative entry. I don’t see this fern often in Vermont, and it seems rare here in the Eastern Piedmont. You won’t find it in this handy guide to the ferns from the Vermont Department of Forests, Parks and Recreation. The guide is a bit dated but worthy for beginning fern fanatics. See the images and captions below for more.


Here’s more of the underside of that fern frond with its sori. / © Bryan Pfeiffer

And here's the upper-side of the fond. / © Bryan Pfeiffer

And here’s the upper-side of the fond. / © Bryan Pfeiffer

Finally, here's Braun's Holly Fern is all its glory (with Mary Crane's boot and hiking pole in there for reference).

Finally, here’s Braun’s Holly Fern is all its glory (with Mary Crane’s boot and hiking pole in there for reference). / © Bryan Pfeiffer

  1. Sue Cloutier says:

    Polystichum Braunii; Braun’s Holly Fern with sori

  2. Bryan says:

    OK, everyone is close. Nobody yet has it to species. I’m thrilled folks are taking the time to work on this. Thanks! And I’m particularly grateful for replies here from two of my heros: botanist Peter Hope and novelist Sara Backer.

  3. Rob Anderegg says:

    fern fruiting bodies

  4. mark says:


    my firend. Sori.

  5. Sara Backer says:

    Ah, yes, I recognize these. They are mutations of the prize raspberries in the now-antique video/arcade game called Ms. Pac Man. Their brown hue did not appeal to gamers, but instead of dying on a floor in Silicon Valley (the usual fate of pixellated rejects) they found a way to escape cyberspace and start colonizing on broad leaf ferns. A video would show they still move horizontally and vertically as if in the Ms. PacMan maze.

  6. Sue Cloutier says:

    The others I knew without looking them up; this I went to my field guides! I think this may be the sori of the Male Fern, Dryopteris filix-mas Scott, 1834 as illustrated by Edgar Wherry (1929) and Herbert Durand (1961) in their field guides.

  7. Laura Guion says:

    This is a fiddlehead fern leaf.

  8. Peter Hope says:

    I know what it is but I don’t count tho; you can wait until a non professional fernattic gets it – nice shot

  9. Susan Hindinger says:

    Spores on common polypody?

  10. Judy Brook says:

    I’d guess Boott’s Fern (Dryopteris X Boottii) a hybrid between D. spinulosa and D. cristata. It’s the only one I can find with toothed leaflets and that pattern of sori. But my Boughton Cobb Field Guide to the Ferns is dated 1963. Bet all the scientific names have changed since then. Looking forward to being with you this Saturday.

  11. alice porembski says:

    fern spores

  12. sue says:

    Fern spore

  13. Emily says:

    It looks like mature sori, a cluster of sporangia on the underside of I don’t know what species of fern frond.

  14. Patti Haynes says:

    What’s this #4 Looks like reproductive spores under a fern leaf. As to the fern, my guess is Christmas.

  15. Louise Giovanella says:

    Sorry for the typo.. I meant Dryopteris marginalis

  16. Louise Giovanella says:

    Could it be Dryopteris marginalia?

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