Note where the fern is growing. This species often grows on trees, not on the ground. It particularly favors maple and cottonwood trees. Like most ferns, it is mostly found in damp, shady habitats, for example near streams, although it tolerates some direct sunlight.
Measure the largest leaf, which should be about 11 to 18 inches long. If it is much larger or much smaller, you might be looking at another species.
Examine the overall structure of the plant. Licorice ferns usually have widely spaced leaves in comparison to similar species.
Examine the leaves and stem, using a magnifying glass if you have one. Another distinguishing characteristic of this fern is distinctive hairs on the stem.
Crush a little of the stem, if the fern is growing abundantly. As the name suggests, licorice ferns taste of licorice. It is not a good idea to go around sampling wild plants, but you can smell it. Although the rhizomes -- the base of the stems from which the roots grow -- are the edible part, there should also be a faint aroma of aniseed from the upper stem.