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My What’s This? challenge returns with these oddities from southeastern Michigan on 3 June 2014. The first to name them wins prestige and $5 off any of my outings or workshops. Enter in the comments section below.

Tomorrow I’ll post the winner and responses from other folks who got it right.

Find my 18 other What’s This? challenges here.

Added June 5: We have a winner!

Skilled field naturalist and artist Susan Sawyer was first to identify these as the fertile fronds of Cinnamon Fern (Osmundastrum cinnamomeum) and Royal Fern (Osmunda regalis), side by side in wet woods at Proud Lake Recreation Area in southeastern Michigan.

Their third close relative, Interrupted Fern (Osmunda claytoniana), which prefers drier soils, was not to be found. You can see a bit of each plant’s sterile fronds below, particularly Royal’s distinctive, broadly pinnate fronds.

All three species bear spore-producing parts on separate fronds. In other ferns, like the Braun’s Holly Fern further below, the spores mature on the underside of fronds.

In that final photos, each of those dots in the array is called a sorus (plural sori). In each sorus is a clusters of capsules that produce spores. We call each capsule a sporangium (plural sporangia).

In any event, if you guessed millet or amaranth or some other grain, you’re not alone. I got a few of those. Along with Susan, you’ll find other correct answers in the comments section. Onward to the sporosphere!

Fertile fronds of Cinnamon Fern (left) and Royal Fern.

Fertile fronds of Cinnamon Fern (left) and Royal Fern.


Sori on Braun’s Holly Fern / © Bryan Pfeiffer


  1. Susan Sawyer says:

    Cool to get those both in one photo. Now for another challenge, find the spores on Bracken.

  2. Ron Wiesen says:

    2 fruiting bodies of ferns – 1 cinnamon and 1 royal?

  3. Judy Brook says:

    I think you have fertile fronds of Cinnamon Fern on the left and Royal Fern on the right.

  4. Linda Wurm says:

    Have you been fern frolicking?These are the fertile fronds of two different ferns. Cinnamon fern and maybe royal fern?

  5. Sue Cloutier says:

    Fertile fronds of Osmunda cinnamomea and Osmunda regalis

  6. fertile fern fronds; left is cinnamon fern, right looks like royal fern

  7. Susan Sawyer says:

    cinnamon & royal fern fertile fronds!

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