Adiantum villosum L.

  • Authority

    Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.

  • Family

    Pteridaceae

  • Scientific Name

    Adiantum villosum L.

  • Description

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    Species Description - Rhizome short-creeping, 5-8 mm diam.; rhizome scales light brown with dark brown thickened walls, linear-lanceolate, 1.5-2.0 mm long, 0.1-0.3 mm wide, denticulate with recurved teeth; fronds clumped, 50-100 cm long; stipe ca. 2/3 of the frond length, angled, lustrous, atropurpureous, with small brown scales (to 3 mm long); blade ovate, 25-40 cm wide, bipinnate; pinnae 3-4 pairs and conform terminal pinna, alternate, terminal pinnule conform, pinnules not much reduced at base of pinnae, largest pinnule 20-35 mm long, tip acute, sides of pinnules forming right angle at pinnule base, upper surface glabrous with idioblasts, lower surface with scattered pectinate scales (0.8 mm long); sori on both top edge and outside edge, several per segment, 1-4 mm long; indusium glabrous; spores tan.

  • Discussion

    Type. Discussed in detail by Proctor (Fl. L. Antill. 2: 185. 1977), who designated as neotype BM-Sloane, Herb. 1: 127. Jamaica, nr. Spanish Town. The acute-tipped pinnules with right-angle base pinnules distinguish this taxon among the bipinnate, idioblastic species with large pinnules and hairs on the pinna undersurfaces. Abortive-spored hybrids between A. villosum and A. pulverulentum with large, acute pinnae, sori one per segment, and glabrous indusia were found in Oaxaca (Mickel 5777. NY, Fig. 41F, Tuxtepec, 50-100 m elev.; Conzatti et al. 3147.5, US, Pochutla, 600 m) and Veracruz (Mickel 7226b, NY, Playa Vicente). An abortive-spored hybrid with A. trichochlaenum was found in Chiapas (Purpus 6864, NY), having large pinnae with papillate emergences on the indusium.

  • Distribution

    Terrestrial, in wet forests; Juchi-tán, Tuxtepec; 50-400 m. Mexico (Ver, Oax, Chis, Tab); Guat to CR; WI, Trin, Tob; Ven & Col to Peru & Braz.

    Mexico North America|