Amer. Fern J. 77: 38. 1987
North America, Mexico, West Indies, Central America, South America.
The species of Argyrochosma traditionally have been assigned to either Notholaena or Pellaea. Comparative studies (M. D. Windham 1987) have revealed that members of Argyrochosma are not closely related to Notholaena as typified by N. trichomanoides (Linnaeus) Desvaux. The two genera show consistent differences in stem and leaf morphology, sporangial distribution, spore color and ornamentation, chromosome base number, gametophyte morphology, and chemical composition of the farina.
Argyrochosma is more closely related to Pellaea (M. D. Windham 1987) and members of these genera are occasionally confused. These two groups are easily distinguished, however, based on the presence or absence of farina, leaf segment size and shape, and characteristics of the stem scales and leaf margins. In addition, all species of Argyrochosma thus far examined have a chromosome number based on x = 27, unique among cheilanthoid ferns. These differences suggest that Argyrochosma is monophyletic and worthy of recognition as a distinct genus.
Species ca. 20 (6 in the flora).
|1||Abaxial surfaces of blades glabrous, lacking whitish farina.||> 2|
|1||Abaxial surfaces of blades obscured by whitish farina.||> 3|
|2||Ultimate leaf segments articulate, dark color of stalks stopping abruptly at segment bases; rachises flattened or shallowly grooved adaxially; margins of fertile ultimate segments usually revolute, often concealing mature sporangia.||Argyrochosma microphylla|
|2||Ultimate leaf segments not articulate, dark color of stalks continuing into segment bases abaxially; rachises rounded adaxially; margins of fertile ultimate segments plane to somewhat recurved, not concealing mature sporangia.||Argyrochosma jonesii|
|3||Ultimate leaf segments articulate, dark color of stalks stopping abruptly at segment bases; margins of ultimate segments plane, not recurved or revolute; sporangia following secondary veins for most of length.||Argyrochosma incana|
|3||Ultimate leaf segments not articulate, dark color of stalks continuing into segment bases abaxially; margins of ultimate segments usually recurved or revolute; sporangia following secondary veins for short distance near segment margin.||> 4|
|4||Pinna costae distinctly flexuous; branches arising from prominent angles.||Argyrochosma fendleri|
|4||Pinna costae straight or nearly so; branches not arising from prominent angles.||> 5|
|5||Petioles chestnut brown, 0.50–0.75 mm diam.; blades somewhat herbaceous; veins often visible adaxially; sporangia containing 64 spores.||Argyrochosma dealbata|
|5||Petioles reddish brown to black, usually more than 0.75 mm diam.; blades leathery; veins obscure; sporangia containing 32 spores.||Argyrochosma limitanea|
|Author||Michael D. Windham +|
|Authority||(J. Smith) Windham +|
|Basionyms||Notholaena sect. Argyrochosma +|
|Distribution||North America +, Mexico +, West Indies +, Central America + and South America. +|
|Etymology||Greek argyros, silver, and chosma, powder, referring to whitish farina covering the abaxial surface of leaf blades in most species +|
|Illustration copyright||Flora of North America Association +|
|Illustrator||John Myers +|
|Publication title||Amer. Fern J. +|
|Publication year||1987 +|
|Reference||tryon1956a + and windham1987b +|
|Source xml||https://firstname.lastname@example.org/aafc-mbb/fna-data-curation.git/src/f50eec43f223ca0e34566be0b046453a0960e173/coarse grained fna xml/V2/V2 89.xml +|
|Taxon family||Pteridaceae +|
|Taxon name||Argyrochosma +|
|Taxon parent||Pteridaceae +|
|Taxon rank||genus +|
|Volume||Volume 2 +|