Cheilanthes
-
Authority
Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.
-
Family
Pteridaceae
-
Scientific Name
-
Description
Genus Description - Terrestrial or epipetric; rhizomes compact to long-creeping, occasionally ascending, scaly; roots wiry; fronds monomorphic, small to medium-sized, 1- to 5-times pinnate, hairy, scaly, farinose, or glabrous abaxially; veins free; sori near the blade margins, usually with the margins inrolled and differentiated; spores tetrahedral-globose; x =29, 30.
-
Discussion
Type: Cheilanthes micropteris Sw.
Cheilanthes has approximately 150 species, mostly of warm, dry, rocky regions, with nearly half the species in dry parts of Mexico and the southwestern United States. The apogamous condition in many species is generally suggested by the presence of 32 spores per sporangium rather than the customary 64, and some species have more than one cytotype. Blade indument is highly diverse in the genus. Scales show every transition to hairs in the C. lendigera complex. A few species have hairs with a glandular tip. Some species have hairs ascending to spreading directly from their bases, but many species have a unique type of hair with the basal 2-4 cells very small, generally starting basiscopically and then having larger cells that grow acroscopically (Fig. 87N). Cheilanthes has undergone major changes in circumscription recently. For many years Notholaena was separated from Cheilanthes on the basis of the sori running along the veins near their tips and the blade margins not differentiated, but these characters were shown to be artificial and unreliable as generic characters. Mickel (1979, 1992) and Mickel and Beitel (1988) combined the two under Cheilanthes. Cheilanthes is sometimes confused with Pellaea, and several species traditionally maintained in the latter genus are here treated in Cheilanthes and Argyrochosma. There are several natural species groupings still within Cheilanthes, but at what level they should be recognized is still uncertain. Molecular studies by Gastony and Rollo (1998) indicate that Cheilanthes, as defined here, is polyphyletic and might better be divided into several genera. Some species should perhaps be treated in other existing genera, e.g., C. aurea, C. aurantiaca, and C. leucopoda may be better placed in Notholaena, C. farinosa in the principally Asian genus Aleuritopteris. In other cases, genera recognized as distinct in this treatment are perhaps better in Cheilanthes, e.g., species treated herein as Mildella.