Notholaena, commonly known as cloak ferns, is a genus of ferns in the family Pteridaceae (order Polypodiales). Around 34 species are currently recognised, distributed primarily across the warm arid and semiarid mountain ranges of the Americas and adjacent regions, where most members grow epipetrically on rock surfaces or in coarse, gravelly soils.
Plants typically bear a creeping or erect rhizome and leaves that are pinnatifid to pinnate-pinnatifid. The marginal sori lack a true indusium and are instead protected by the reflexed margin of the leaf blade — a false indusium that gives the genus its common name. A defining feature of Notholaena is the presence of a whitish or yellowish farina on the underside (abaxial surface) of the leaves. This powdery coating is a secretion of lipophilic wax exudates, and in Notholaena it uniquely extends to the margins of the prothallium (the gametophyte generation) — a trait almost exclusive to this genus and rarely encountered even in close relatives such as Argyrochosma and Aleuritopteris.
The genus is closely related to Argyrochosma, which also produces farinose leaves, but Notholaena is distinguished by its lobed or pinnatifid ultimate leaf segments that are sessile or nearly so, whereas Argyrochosma has entire-margined, distinctly stalked segments. Notholaena was historically treated as a broad catch-all for ferns of arid environments that did not fit comfortably elsewhere; modern phylogenetic work has greatly narrowed its circumscription — the genera Argyrochosma and Astrolepis have been segregated from it, and numerous former members have been transferred to Cheilanthes.
The name was established in 1810 by the Scottish botanist Robert Brown, derived from the Greek νόθος (nothos, "false") and χλαῖνα (chlaena, "cloak"), alluding to the leaf-margin false indusium rather than a true, well-differentiated covering tissue.
Etymology
The genus name Notholaena was coined in 1810 by Robert Brown, derived from the Greek νόθος (nothos, "false") and χλαῖνα (chlaena, "cloak"). It refers to the fact that the sori are sheltered not by differentiated indusial tissue but by the reflexed margin of the leaf — a "false cloak." Members are commonly known as cloak ferns.
Distribution
Notholaena species are most abundant and diverse in the warm arid and semiarid mountain ranges, particularly across the Americas. They grow predominantly on rock surfaces (epipetrically) or in coarse, gravelly soils. No detailed GBIF distribution polygons are available for the genus as a whole; range information is species-specific.
Ecology
Members of Notholaena are adapted to xeric, rocky habitats — cliff faces, boulder fields, and gravelly mountain soils in semiarid zones. The waxy farina coating on the underside of leaves and on gametophyte prothallium margins is understood to be an adaptation reducing desiccation and possibly UV exposure. Sori are protected by the reflexed leaf margin rather than a true indusium.
Taxonomy Notes
Notholaena was long used as a heterogeneous catch-all genus for arid-adapted ferns; modern circumscription is much narrower. Argyrochosma and Astrolepis were segregated from Notholaena as distinct genera, and many other former members were transferred to Cheilanthes. As of July 2025, the Checklist of Ferns and Lycophytes of the World recognises 34 species. GBIF records 33 accepted descendants. The genus belongs to the family Pteridaceae, order Polypodiales, class Polypodiopsida.
