12. Pellaea Link, Fil. Sp. 59. 1841.
旱蕨属 han jue shu
Authors: Zhang Gangmin & George Yatskievych
Plants usually on rocks. Rhizomes erect to decumbent or long creeping, siphonostelic; scales concolorous or bicolorous, brown to nearly black, sometimes with narrow pale margins, narrowly lanceolate or subulate-lanceolate to lanceolate, margins entire or toothed. Fronds monomorphic or slightly dimorphic, clustered or more widely spaced. Stipe usually brown to black, usually lustrous, terete or adaxially grooved, with 1 vascular bundle at base. Lamina oblong-lanceolate to deltoid-lanceolate, 1-4-pinnate, with a discrete terminal pinnule or segment, usually leathery, thick, glabrous on both surfaces or occasionally hairy or scaly. Ultimate pinnules or segments stalked, or if sessile then narrowly attached, variously shaped, sometimes with 1 or 2 blunt basal lobes, margins entire, apex rounded to acute. Veins free or rarely anastomosing, pinnately branched. Sori small, orbicular, at vein tips, usually confluent at maturity. False indusia linear, continuous, usually narrow, margins entire or erose. Spores globose-tetrahedral, perispore granular, cristate, rugose, or rarely tuberculate to verrucate. x = 29, 30.
About 30 species: S Africa, Asia, Australia, North and South America, Pacific islands (New Zealand); two species (one endemic) in China.
Traditionally, the genus Pellaea was circumscribed broadly to include 45-50 species in four sections distributed on most continents. However, this version of Pellaea is polyphyletic and includes several distantly related groups. Of the two Chinese species treated here, P. calomelanos is clearly a member of P. sect. Holchochlaena Hooker & Baker, which includes 10 or more species with a center of diversity in Africa. In the future, it is likely that this group will be raised to generic status, as it is only distantly related to P. sect. Pellaea. The systematic position of the rare P. connectens has not yet been evaluated because of the lack of recently collected material, but it likely is related to P. calomelanos. Other species included in Pellaea in some of the literature on Asian ferns are here treated in Cheilanthes, including those sometimes segregated under the generic name Mildella.