PTERIDACEAE

BRAKE FAMILY

Alan R. Smith and Thomas Lemieux

Perennial, in soil or on or among rocks; rhizome creeping to erect, scaly
Leaves generally all ± alike (or of 2 kinds, fertile and sterile), generally < 50 cm, often < 25 cm; petiole generally thin, wiry, often dark, in transverse section with vascular strands generally 1–3, less often many in a circle; blade generally pinnate or ± palmate-pinnate (see Adiantum ), often 2 or more compound, lower surface often with glands, ± powdery exudate, hairs, or scales; segments round, oblong, fan-shaped, or otherwise, veins generally free
Sporangia in sori or not, marginal, submarginal, or along veins, sometimes covered by recurved, often modified segment margins (false indusia); true indusia 0; spores spheric, sides sometimes flat, scar with 3 radiating branches
Genera in family: ± 40 genera, 500 species: worldwide, especially dry areas. Definition of Cheilanthes and related genera problematic; traditional limits often untenable.