The ferns along the trail are Sword Fern and Lady Fern.
A few interesting facts about ferns:
Ferns are ancient plants that developed before flowering plants. A fern does not produce seeds directly, but rather develops spores that grow in cases, called sori, generally appearing as dots on the backs of fertile leaves. Rows of orange-brown shield-covered sori are easily visible on the backs of the fertile fronds of sword ferns.
The spores, when released, do not develop directly into ferns, but rather grow into a tiny leaf-like structure called a prothallium. The prothallium produces eggs and sperm that unite to generate new ferns. It takes several years for a fern to grow from a spore.
The leaves and roots of ferns grow from underground rhizomes that can be extensive and live for many years. Though the leaves, or fronds, of many ferns die back in winter, the rhizome survives to sprout new fronds in spring.