Ophioglossum pusillum is an easy species to identify in
Wisconsin, but it is uncommon and may be easily overlooked. The
blade is simple and there is a separate fertile branch (sporophore)
arising near the base of the blade. Blades are up to 10 cm long
and broadest near the middle. Our only other fern with a simple
blade is Asplenium rhizophyllum
which does not have a separate fertile branch and the blades are
widest near the base.
O. pusillum is known from Nebraska to Ontario, east to
New Jersey and New Brunswick. It is also known from British Columbia
and the northwestern U.S. In Wisconsin it is a "special
concern" species, documented from fewer that 40 scattered
localities, and is apparently absent over a large portion of northern
Wisconsin. Habitats are mostly moist, grassy sites.