Marginal shield fern

Marginal shield fern reproduces mainly by spores. These give rise to the male and female gametes needed for the species to reproduce.

Spore production runs from May to September, peaking in July and August. After spores germinate and fertilization occurs, tiny green, heart-shaped structures called prothalli form, typically on the underside of the fronds. A spore can take about two weeks to develop into a prothallus.

A young frond, or plantlet, then grows from these structures in summer or early fall. It becomes a new fern in about 14 weeks.

This fern can also spread through its rhizome, which is short, thick, and sturdy. However, vegetative reproduction is slower than in many other species. As a result, it tends to form compact colonies and dense mats rather than sprawling stands.

Marginal shield fern also hybridizes readily with other Dryopteris species.