Rusty Woodsia?

Isn't this a cute little thing? The blade of this little fern is only 3-4 inches long. It grows out of the side of the gully that I walk down to access the creek in the cemetery.

I've been trying to figure out what it is for about three years. Here's where I think I went wrong:



So, I did the first part... is it undivided, once, twice, or thrice divided? Well, it's twice divided. The blade has pinnae and there are pinnules, but the pinnules are smooth.

The next question in my key is: "is the blade clearly broadest at the base?" What do you think?

While you are pondering this, let's talk about today, before I give you the answer. It was one of those days that I COULD NOT stay inside. The sun was shining, but the air was cool. I've been working on a "secret" project for a couple of years. You can read about it at Exploring Like a 10-Year Old. Today I went back and double checked a piece of it on foot. Walked about 8 miles!

What did you decide about the fern? I kept saying that it was broadest at the base. But that is apparently the wrong answer. After looking more carefully at a LOT of the blades, I guess I can believe in that decision. At any rate it led me to choices that made sense, sort of...

Next I had to decide if it has spores on a separate stalk or on the backs of the pinnae. That wasn't too hard, even though the spores aren't visible at this time of year. If they were on a separate stalk that stalk would probably be seen dried up in the old plant parts.

Next... I'm in trouble, because they want to know the shape of the sori. The sori are the spore cases on the backs of the leaves. Wrong season, and I seem to always be off hiking when this happens, because I've never seen them. So I was reduced to looking at pictures, but I've narrowed down the choices. I settled on one of the Woodsias- the size is right. There are seven choices! OK, there are some differences, but it seems to be Woodsia ilvensis, rusty woodsia.


Here's the first problem. The plant is supposed to be a lot more hairy than this. Also, the stipe is supposed to be brown.

For smooth woodsia the stipe is yellow-green and the back of the blade is smooth. That sounds more like what I see here. BUT... smooth woodsia only has 2-4 pinnules per pinna, while rusty woodsia has 3-9. This one is definitely the 3-9 count.

For a definitive answer I'll just have to catch this when the spores show up. Then it will be unmistakable. The plant gets really hairy and rusty brown. But... I usually seem to be off hiking at spore time. Stay tuned... it may only take me a few more years to get this. Meanwhile, I just think it's really cute!

Update Note: April 2011- This fern has been identified, almost certainly, as Fragile Fern, Cystopteris fragilis

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