Showing posts with label Ophioglossum. Show all posts
Showing posts with label Ophioglossum. Show all posts

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.

Saturday, April 17, 2010

Adder's Tongue Fern

This tiny plant is called Ophioglossum or Adder’s Tongue Fern. At barely two inches tall, it produces a single, fleshy leaf. Mature plants will also produce a stem bearing the spore producing structures. I think this is a lovely little plant and enjoy finding it scattered widely across Blue Jay Barrens.

Adders Tongue Ferns often grow in bunches or colonies of many plants. I find them primarily in historically undisturbed areas such as old fence rows and field corners. In some locations they appear to be migrating into the adjoining fields.

My personal name for this fern is the Aggravation Plant, because of the aggravation is causes when I try to identify it to species. There are several species of Ophioglossum and they are all similar in appearance. There are two that are known to occur in this area and a third that is found a couple of counties to the east and could possibly show up here. The problem may be that I have too many plant ID references. If I look in just one book, it’s not hard to come to a definite conclusion. It’s when I try to verify that ID in another book that things fall apart. The plant shown here neatly fits the description of the species that has leaf blade fully open and leaf tip rounded.

However, the next plant down the line fits exactly, the definition of a different species that displays a folded leaf blade and a pointy leaf tip. Two species side by side? Not likely. When you scan the surrounding population, you see leaves of every shape and all gradations in between. Of course, there are some other characteristics that the books describe as being more definitive.

Most books point to the venation as being the defining character. Well, these are some thick leaves and no amount of sunlight shining through the back of the leaf is going to allow you to get a good look at the veins. The easiest way I’ve found to view the veins is to drop a fresh leaf into alcohol to remove the chlorophyll and then put the leaf under a dissecting scope. What I see is a pattern of leaf venation that doesn’t match any of the illustrations in the books. Fortunately, the plants don’t have a long season, so when they soon whither, I will assure myself that next year will be my time to crack the Adder’s Tongue Fern mystery.