Underside of resurrection fern with sori visible. Sori contain spores that are the fern's method of reproduction. NPS Photo. Phone: Looking around the forests and clearings of Fort Matanzas National Monument it is easy to spot a variety of different plants, all of which have adapted to their local environment. One type of vascular plant that is more primitive than most are ferns. By definition, ferns are plants without flowers or seeds. They have feathery leaves (fronds) and reproduce by spores released from the underside of the leaves. Here at the park there are four different fern species present, all of which are noteworthy in their own right.