Monday, May 16, 2011

Adder's Tongue Fern

Adder’s Tongue Fern is one of those low growing plants that is inconspicuous to the casual observer. It’s usually surrounded by other non-descript plants that blend into a bright green ground cover. I make a point of looking for it each spring.

This is Ophioglossum vulgatum, although positive identification of this genus can cause a certain amount of frustration. Different sources rely on varying descriptions of physical characteristics when describing the different species. In particular, I’m certain that I have Ophioglossum vulgatum, but I’m not sure that I don’t also have the rarer Opioglossum engelmannii.

There is a wide variation of leaf shape within each population of plants I examine. Leaves might be short and broad with a rounded tip or long and narrow with a pointed tip or wide with a blunt tip with a tiny spur. Some leaves have a central crease while others don’t. Some curl forwards on the sides and others arch backwards. There can be a whole range of shapes and sizes all in the same patch of plants. Trying to match physical characteristics to written descriptions can be very frustrating.

One characteristic that is supposed to be definitive for identification purposes is the pattern of leaf venation. You can see that this thick, fleshy leaf does not easily divulge the secrets of its veins.

I picked a couple of leaves and treated them to an alcohol bath to remove the chlorophyll. It turns out that venation can also vary greatly within an individual leaf. For the most part, the veins tended to match the patterns illustrated for vulgatum. When the plant nears the end of its season, I may do a more extensive collection of leaves and check venation. Collecting leaves late in the season should reduce stress on the plants donating to the collection.

I originally found these ferns growing in the old fence rows. Through the years I have seen a rapid increase of plants showing up in the fields. Most of the plants are found in dry, calcareous areas that more match the preferred habitat of engelmannii, so this adds to the feeling that this rarer species might also inhabit Blue Jay Barrens.

When you don’t have time to do extensive flora surveys of an area, you sometimes wonder if your casual observations of plant population increases might not be totally accurate. This plant, growing in the middle of one of the old crop fields, confirms that my observations are correct. Prior to 1985, plowing and chemical applications to this field would have made the existence of this plant impossible. This plant has to have arrived here after my management activities began.

It’s not just one plant showing up in the field that gives me confirmation. This whole area now supports hundreds of Adder’s Tongue Ferns living among the Indian Grass. Regardless of the species, I enjoy having this plant as a part of the Blue Jay Barrens flora.


  1. Thanks for the photos and info. I've not yet run into the adders tongue around here but I must admit I try to cover alot of ground and I tend to scan for any hints of colors as I scrounge about so I may have missed some.The only similar plant I find is Jack-in-the-pulpit. Probably because its so large you cant miss it! lol.

  2. Michael, I hope you're lucky enough to run into some of these neat little plants. I'm also attracted to anything with color, but I sometimes spend hours combing through areas as small as a few hundred square feet. It's amazing how many tiny things of interest there can be squeezed into a small space.

  3. These are not something I've ever seen.
    I appreciate all the information you've provided here and will be more vigilant when walking around in your side of the state.

  4. Hi, Nina. The Adder's Tongue Fern has a rather long season, so there should be many opportunities to see them. They are about mid-way through their season now and should be around for several more weeks. I hope you get to see some.

  5. Hey Steve! Thanks for a full post on the adder's tongue. I have never seen them in person, nothaving been in the right place at the right time. Great photos and nice to see the veination. Beautiful!


  6. You're welcome, Wilma. I hope it's not long before you get to see the real thing.

  7. I'd like to see this species some day. Interesting study you are doing on the venation!

  8. Hi, Mike. I hope the venation study one day allows me to be comfortable with my identification of the species or even better, shows that I do indeed have more than one species growing here.