4. Pellaea (cliff brake)
Rhizomes compact, ascending (creeping elsewhere). Leaves 1–3 times compound,
sometimes somewhat dimorphic, the vegetative leaves with pinnules more than 1
cm long, more than 5 mm wide, the fertile leaves with somewhat narrower
pinnules. Veins difficult to observe, with 1–3 lateral branches. Sporangia
along the terminal portions of the veins, partially covered by the strongly
reflexed pinnule margins, these usually with a differentiated, scarious edge.
Spores 32 or 64 per sporangium, 25–80 mm in diameter, tan (brown elsewhere). About 40
species, nearly worldwide, except Europe.