Connecticut Plants
Interrupted Fern
Osmunda claytoniana L.

Interrupted fern gets its name from the brown fertile leaflets, which "interrupt" the green sterile leaflets on the larger fronds.

  • Family: royal fern (Osmundaceae)
  • Habitat: rich, mesic woods and open woods; shaded roadsides
  • Height: fronds 2-4 feet long
  • Location of spores: in middle of fertile leaflets
  • Petiole (leaf stalk): round in cross-section, sometimes bearing fuzzy tufts, ungrooved
  • Growth pattern: symmetric clump
  • Persistence: deciduous
  • Origin: native
Osmunda claytoniana L.

An interrupted fern unfurling its fronds in spring. At this time of year, the fertile leaflets are dark brown.

Osmunda claytoniana L.

"The green sterile leaflets are ""interrupted"" by a few fertile leaflets. In this photo, the fertile leaflets have their mature color of light brown."

Osmunda claytoniana L.

Top part of an interrupted fern frond. Note the fairly blunt tips of the leaflets; this characteristic helps distinguish interrupted fern from its relative, cinnamon fern, which has very pointed tips.