Interrupted Fern
by Pam
Even though I’m a major tree lover from the time I could climb them, I also love the large diversity of plants and other living things that grow on and underneath trees, including wildflowers, club moss, mushrooms, moss, lichens, liverworts, horsetails and ferns.
Ferns were just interesting green things I used to appreciate but never really thought about identifying until I took a field botany course and found out identifying ferns is really not hard at all! The best book for identifying ferns is Fern Finder, by Anne C. Hallowell and Barbara G. Hallowell.
This particular book is a guide for native ferns of central and northeastern US and Eastern Canada. There is the Pacific Coast Fern Finder, also.
One fern that doesn’t need keying out is the Interrupted Fern (Osmunda Claytoniana). While I read and learned about this unique fern for my class, I never imagined when I first saw it growing at Allegany State Park in May that it would be as tall as it was at that time. The fronds (“leaves”) can grow up to six feet long! Interrupted fern has fertile pinnae (“leaflets”) “interrupting” sterile pinnae in the center of each frond. There are usually two to four pairs of fertile pinnae with dark brown sporangia when they’re ripe. They wither and fall, leaving vacant spots on the leaf stem after midsummer. Here’s what the fertile pinnae looked like at Allegany State Park on May 26th:
Here’s a closer look at the dark brown sporangia on the fertile pinnae:
Interrupted fern doesn’t have any cinnamon colored hairs on its stipe (base of the frond). However, it has some loose fur when it is young, but is smooth when it matures. It prefers dry soil but does well in a variety of places. It serves as a soil anchor in steep rocky localities with sparse soil. Which is interesting because we saw this fern on the old ski slope at Allegany State Park. The ferns were located about halfway down this slope which leads to an old growth forest:
This fern grows from Newfoundland to Manitoba south to western North Carolina, northern Georgia and Alabama, Tennessee, Missouri, Iowa, and Minnesota.
I hope you’ll go to the woods and start getting really close to ferns and keying them out – unless you already have! Thanks to Tom for allowing me to be a guest on his blog, and for letting me share my love of the interrupted fern, and ferns in general!
Sources: Palmer, Laurence, Some New York Ferns, The Conservationist, August-September 1962
Lellinger, David B., A Field Manual of the Ferns & Fern-Allies of the United States & Canada, Smithsonian Institution Press, 1985.
P.S. I would list my Fern Finder as a source but I lent it out to a good friend. Which reminds me, I need to get that book back so I can have more fern fun myself!
This guest post was written by NatureWoman.
Mon@rch's Nature Blog 
Pam, what an awesome fern post you did about one of the best ferns ever!! I love how you were able to get Allegany State Park in with this guest posting!! HIGH FIVE!
31 August 2007 at 10:53 pm
Hey! Nature Woman. Good job:0) I love this fern and have a few in my back yard. I salvaged them 25 years ago before the bulldozers cleared an adjacent woodlot for a housing development.
31 August 2007 at 11:26 pm
Thanks for the info about ferns – I really need a book – Fern Finder sounds perfect. Congrats, Pam, on a great post.
1 September 2007 at 1:10 am
Great post! A lot of fern info here. Thanks for filling in for Mon@rch.
1 September 2007 at 2:25 am
Ah, so these are interrupted ferns? From the ski slope:
http://outdoors.webshots.com/photo/2768324930073980806bjGzvw
~ Nick
1 September 2007 at 5:49 am
I feel like a dolt! We have copies of Flower Finder and Tree Finder, but I had not realized there were more books in the series until I saw the cover pic you posted. Montessori schools often use this series, in an effort to teach key characteristics of families, rather than simple flashcard-type identification. I looked up the other titles in the series, and found Winter Weed Finder, which is going to be a lot of fun! Also, the books are apparently published in Rochester! Thanks, that post was fascinating. Aren’t you supposed to be on vacation?
1 September 2007 at 4:44 pm
Thanks for the info on ferns – they do seem to be the forgotten part of the forest floor. When traveling over here I considered getting this book and bypassed it for a more popular editable and non edible plants of the west. This was a great post… and an excuse on my part to get another book. thank you.
1 September 2007 at 5:04 pm
Wonderful post Pam!
2 September 2007 at 8:53 am
You go, Pam! Awesome post :o)
2 September 2007 at 11:20 pm
As I am not botiny-ly inclined, all I can say is Wow! That’s a cool plant!
(The title made me think: “Fern, Interrupted”
2 September 2007 at 11:21 pm
@Mon@rch – Thank you! This is an awesome fern and I wish I captured a photo of you standing next to them! High Five back at you!
@Cathy – Thank you! I love that you were able to save this fern before they got leveled!
@NatureShutterbug – You’re welcome, and thank you! I hope you enjoy the Fern Finder!
@Barbara – Thank you! It was my pleasure!
@Nick – Yes! I love your photo! That’s exactly like the one I wish I had captured!
@Saille – I couldn’t believe how many “Finders” there were out there, either! I hope you enjoy them all.
@aullori – You’re welcome! I agree with you about them being forgotten, along with the other forest life!
@Jayne – Thank you – I’m glad you enjoyed it!
@Mary – Thank you! Can you tell I love ferns!
@Susan – It sure is cool, and I hope you see it in your travels!
3 September 2007 at 5:36 am
Pam I’m a bit late at posting this but want you to know this was very informative. My husband and I sure enjoyed our wildflower classes at the nature pilgrimage where we learned a bit about ferns. I’ll have to check out your book recommendation.
3 September 2007 at 9:25 am
Very helpful post, especially for the fern book recommendation. I’ve been curious what ferns we have in our region (SF area), and now I have a book to look for. Not like I really /need/ any more ID challenges what with the birds, the wildflowers, and the butterflies, but hey, the more the merrier, right?
Again, great guest post, NatureWoman!
3 September 2007 at 10:55 am
Ferns are Fun, boy was that bad, great post Pam.
3 September 2007 at 12:52 pm
@ Everyone, thanks and I really have to thank Pam again for such an awesome post! Thanks for helping fill in over the holiday!
3 September 2007 at 8:25 pm
Thank you Pam for a wonderfully informative post! I need to get out and really looking at ferns
3 September 2007 at 10:17 pm
Don’t you hate it when field guides leave out something! Glad that you were there to the rescue!
I remember getting my Audubon Field Guide to Butterflies and being really disappointed in how much was left out and the disorganization of it. I found Butterflies through Binoculars to be much better, but I would have never known to look there unless someone familiar with it had told me (which they did).
I guess, if you’re going to do a field guide, you need to be inclusive or tell users it’s a selected guide.
4 September 2007 at 9:45 am
Marty – I prefer using the Kaufman guide over the Butterflies through Binoculars guide! Much more organized pictures are better framed!
4 September 2007 at 7:56 pm