Shape: A vase shaped fern, to 3+ feet in height, whose shape is very similar in appearance to the Cinnamon Fern, but unlike the Cinnamon, the Interrupted Fern frond can bear both sterile and fertile pinnae (pinnae is the plural of the smaller leafy side branches that grow off the main stem- individually they are pinna, and if the pinna itself has one or more distinct secondary segments, these are called pinnules). The fertile fronds are more erect, the sterile fronds more spreading. Fronds: A fertile frond is interrupted in the middle by smaller spore producing pinnae that resemble brown clusters of very small grapes. These are the "sporangia". Above and below that "interruption" the sterile pinnae are the normal yellow-green color. These brown fertile pinnae turn dark brown after they have discharged their spores and fall off in late summer. These fertile pinnae, during their time on the plant, remain small and are thus interrupted in their growth. There is also a lack of hair at the base of the pinnae which helps distinguish this fern from the Cinnamon Fern whose sterile fronds look similar to the sterile fronds of Interrupted Fern. The pinnules become wider toward the stalk. The main pinnule vein is unbranched. The fiddleheads (Croziers) with their woolly white hair, typical of Osmundas, are some of the earliest to emerge in spring. Mature fronds are smooth and free of hair. Croziers were once considered edible but are now known to be carcinogenic.

Habitat: Interrupted Fern grows in both shade and open areas. The plant prefers alkaline, drier soils, well drained, not marshy. Roots are a tangled mass of wiry black growth growing from a large rhizome. The species name was for the English born Virginia botanist John Clayton, (1694-1773) who lived in Williamsburg. His name is on several other plants, including Spring Beauty, Claytonia virginica.