Argyrochosma formosa Windham

  • Authority

    Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.

  • Family

    Pteridaceae

  • Scientific Name

    Argyrochosma formosa (Liebm.) Windham

  • Description

    Species Description - Rhizomes compact, horizontal; rhizome scales 6–9 mm x 0.3 mm, tan to dark orange, linear; fronds to ca. 40 cm tall, clumped; stipes 1/4–1/2 the frond length, atropurpureous to black, glabrous, terete; blades deltate to ovate-lanceolate, 3–4-pinnate; rachises terete; pinnae 6–9 pairs, alternate to subopposite, glabrous above, gray-green, abaxial surfaces glabrous to glaucous; segments orbicular to inequilaterally cordate, appearing sagittate when folded, articulate, 3–4 mm long and wide, dark axis color stopping abruptly at bases of segments; sori elongate along vein ends, forming a marginal band 0.5–1 mm wide, laminar margins curved, unmodified; fertile segments often folded in half lengthwise; n = 2n=81, apogamous (Oax).

  • Discussion

    Allosorus pulchellus M. Martens & Galeotti, Me´m. Foug. Mexique 47, pl. 10, f. 1. 1842, hom. illeg., non C. Presl, 1836. Allosorus formosus Liebm., Mexic. Bregn. 220 (reprint 68). 1849. Pellaea pulchella (M. Martens & Galeotti) Fe´e, Me´m. Foug. 5: 129. 1852. Pellaea formosa (Liebm.) Maxon, Contr. U.S. Natl. Herb. 24: 61. 1922. Notholaena formosa (Liebm.) R. M. Tryon, Contr. Gray Herb. 179: 99. 1956. Cheilanthes formosa (Liebm.) Mickel & Beitel, Mem. New York Bot. Gard. 46: 113. 1988. Type. Mexico. Oaxaca: S of Sola, Galeotti 6352 (BR!; isotype K!). For additional synonymy, see R. Tryon (1956).

    Argyrochosma formosa resembles A. incana in its black frond axes, stalked segments and being widespread, but lacks farina. The other non-farinose species of Argyrochosma in Mexico, A. microphylla, is distinct by its smaller segments (1–3 mm vs. 3–5 mm) and castaneous (vs. black) frond axes.

  • Distribution

    Dry, rocky, wooded slopes, limestone slopes, steep rocky ravines, thorn scrub, in mortar at Monte Alban; 1250-2700 m. Mexico; Guat.

    Mexico North America| Guatemala Central America|