Monographs Details: Hemionitis
Authority: Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
Description:Genus Description - Terrestrial; rhizome short, compact, erect or ascending, scaly; fronds small, monomorphic or slightly dimorphic; stipe hairy to glabrous, castaneous to stramineous, lustrous; blade palmate to pinnate, hairy to glabrous; veins free to netted without included veinlets; lamina herbaceous, glabrous or with acicular or septate hairs on both surfaces; sori along veins for most of their length, indusia lacking; spores tetrahedral-globose, tuberculate to cristate.
Discussion:Type: Hemionitis palmata Linnaeus.
Gymnopteris Bernhardi, J. Bot. (Schrader) 1799(1): 297. 1799. Type: Gymnopteris rufa (Linnaeus) Underwood [=Acrostichum rufum Linnaeus].
Hemionitis is historically limited to palmate species with netted veins (five species) but that was shown to be an artificial separation from Gymnopteris (Giannasi & Mickel, 1979; Mickel, 1974). Since it is not practicably separated from Gymnopteris, it is here united with it. There are about ten species, mostly of the neotropics, with five in Oaxaca. However, there is still a problem with generic circumscription since H. subcordata, with gymnogrammoid sori, seems to be related to Cheilanthes skinneri with marginal sori. Thus, it seems likely that the genera will have to be redefined without emphasis on the soral configuration.
Hemionitis is distinguished from Bommeria by its sori extending nearly the entire length of the veins.
References: Giannasi, D. E. & J. T. Mickel. 1979. Systematic implications of flavonoid pigments in the fern genus Hemionitis (Adiantaceae). Brittonia 31:405412; Lellinger, D. B. 1969. The taxonomic position of Coniogramme americana. Amer. Fern J. 59: 61-65; Mickel, J. T. 1974. A redefinition of Hemionitis. Amer. Fern J. 64: 3-12; Mickel, J. T. 1987. A new fern from western Mexico and its bearing on the taxonomy of the cheilanthoid ferns. Amer. Fern J. 77: 109-114. Smith, A. R. & J. T. Mickel. 1977. Chromosome counts for Mexican ferns. Brittonia 29: 391-398.