August 17, 2010

A Walk in the Woods: Fern Spores

I was inspired by this post at the wonderful blog Each Little World to take a close look at the spores of the many ferns that I see growing in the woods and around my house. Ferns reproduce differently from flowering plants which create seeds when male pollen fertilizes the female cell, forming a seed with all its genetic material. Ferns are more complicated, with the spores growing into tiny plantlet called a gametophyte, which is fertilized if the conditions are right, with plenty of moisture. This website has a clear explanation of the process.

On my recent walks, I began looking for spores. With some ferns, as in the first photo, the spores are clearly visible growing on the backs of the fronds. The Maidenhair fern, just above, didn't seem to have any spores; but then I noticed faint light colored curves on the outer edges of the individual leaflets, which I believe are the spores. (to see them better, click on the images)

My detective work continued, with the discovery of ferns that had a separate stem for the spores (at least that's what I think it is). I've seen these called "fertile fronds", this one looking like a row of shiny black beads. And below is a large fern, growing along my stone wall in full sun, that has its spores dangling from the stems of the fronds. I enjoyed finding a greater variety in the structure of ferns than I had imagined.


  1. "We have the receipt of fern seed, we walk invisible"
    Shakespeare, Henry IV

    Altoon, these are wonderful photos -- and you did well to figure out the maidenhair. But allow me refine this a little more -- what we can see here are the fruit-dots, or sori. They contain clusters of sporangia, which are little capsules that open and release the spores. And the spores are microscopic.

    The shapes and positions of the sori are very helpful for identification -- these are, from the top, Silvery Glade Fern (used to be Silvery Spleenwort), Northern Maidenhair, Sensitive Fern, and Interrupted Fern. This is a good time of year for fern hunting!

  2. Interesting Shakespeare quote; I wonder if fern "seed" was considered magical?

    Thanks so much for the additional info along with the naming of the various ferns. What great names!

  3. Yes, considered magical because nonexistent -- the function of spores wasn't understood. So fern seed was something ferns didn't have.

  4. Great photos from you and an excellent lesson from Susan — Thank you both! I've never seen anything dangle from a fern as is evident in your last image.

    And did you realize how perfect it looks paired with the first image of the new painting in the prior post. I had the two pictures both up on my computer screen and they made a lovely pair of portraits.