My most recent guided hike was sponsored by The Friends of the Blufflands.
Part of their "Second Saturday" series, Jon Rigden and Max Sorenson guided a fascinating September hike on Hixon Forest's Oak Trail. Our goal was taking a deep dive into learning about the ferns that we would encounter along the trail. Ferns have been a challenege for me so I was especially interested to add to my knowledge.
We started out looking through a microscope at sori (or spores) that are a way to help distinguish each type of fern. Max, a talented artist as well as naturalist, went over a sheet he made describing the parts of a fern and how each part helps in identifying what fern you are looking at. Just sorting out the correct names for the parts of a fern was great learning for me.
 |
| Interrupted fern sori |
We also had the opportunity to look over some recommended field guides that Jon had brought along. Some were small enough to pop into a backpack on the trail like Joe Walewski's highly recommended, detailed but accessible guide Ferns and Allies of the North Woods; Anne and Barbara Hallowell's abbreviated Fern Finder or Lynn Levine's Identifying Ferns the Easy Way; A Common Guide to Ferns of the Northeast.
With these aids and resources examined, we were ready to start doing some serious field identification of ferns and other fascinating plants along the trail.
While there are over 60 different fern species in the Driftless, we concentrated on the six species that we would observe on this hike. Recognizing the sori shapes and colors (whether on stalks or the underside of the pinna), the arrangement of the pinna (leaflets) and the blade shapes made identification much easier
Maidenhair
Sometimes confused with braken, which also has a tall stipe (stalk), its spiraling blade is a sure identifying sign. It's name derives not from this spiral but from its thin black stalks. It is said to remind people of women's hair. Indigenous people used these strong stipes to weave baskets.
Spinulose Wood Fern
These ferns can be a bit tricky to identify. They have smaller pinna (leaflets) on the bottom two leaf pairs. Looking closely at the sori on the pinna's underside reveals light brown, triangle-shaped spores. Each pinna also has a tiny spine at its tip (hence spinulose). That will be the important identifying characteristic for me!
Lady Fern
This delicate and prolific fern's blade is diamond shaped - flaring out from the tip of the blade before once more narrowing at the bottom. The stipe has black "hair" and the sori have a hooked tip which is easily disguished.
Bulblet Fern
They have a very long axis (the stalk within the blade) with somewhat even-in length pinna down the stalk. Turning over a pinna reveals small green bulbs on the underside, which explain their name. In spring, their stipes are red. I have noted many of these on hikes especially in damp woods.
 |
| Bulbs on the bulblet blade's underside |
Interruped Fern
This large species is one of the most ancient ferns.Their sori appear in bunches partway down on the stalk, looking like brown, spent leaves.
Named for its extreme sensitivity to cold, this fern with its blocky pinnules, makes it one of the easiest to identify. Their sori are on stalks and they throw their spores when ready in a process called "explosive dehiscence". The action is similar to that of the jewelweed or touch-me-not, whose seeds launch out at a touch when the pod is ripe. Explosive dehiscence is my new favorite nature phrase!
 |
| Sensitive fern sori, pre-dehiscence |
The Friends of the Blufflands plan to hold two more "Second Saturday" hikes - one in October and one in November. Check their Facebook page or blog near the dates for details on these free guided hikes with great subject information and experts.
Nature School is what I like to call the guided hikes I go on when I’ve a mind to learn more about the natural world and to fulfill my required training hours to maintain my annual Master Naturalist volunteer certification. The Nature School series highlights parks, organizations and groups that provide free or low-cost guided learning experiences while hiking. The Driftless area of MN, WI and IA is rich in dedicated subject experts who share their knowledge, passion and expertise. By doing so, they help hikers of all ages better understand our natural world. It’s always a delight to attend their “schools.”
Check out additional Nature School posts:
