Adiantum villosum L.

  • Authority

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

  • Family

    Pteridaceae

  • Scientific Name

    Adiantum villosum L.

  • Description

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    Species Description - Rhizomes short-creeping, 5–8 mm diam.; rhizome scales dark brown, denticulate, 1.5–2 x 0.1–0.3 mm; fronds clumped, 50– 100+ cm long, arching; stipes atropurpureous, lustrous, 40–55 cm x 2–4 mm, ca. 2/3 of the frond length, with numerous brown hair-like and lanceolate scales 1–2 mm long; blades ovate, 2- pinnate, 25–45 x 25–40 cm wide, with conform terminal pinna; rachises atropurpureous, with lanceolate to hair-like, denticulate scales; pinnae 3–6 pairs, 15–25 x 4–6 cm, alternate; pinnules 20– 35 x 8–12 mm, sides of proximal and median pinnules forming right angle at pinnule bases, distal pinnules on each pinna about 1/2 the length of the longest pinnules, terminal pinnules hastate, non-articulate; veins free, forking, ending in small teeth (sterile pinnules); indument adaxially absent, abaxially the surfaces with scattered tan pectinate scales to 1 mm long; idioblasts conspicuous on both blade surfaces; sori 10–12 per pinnule, along both acroscopic and distal part of basiscopic margins; indusia 1–4 mm long, oblong or slightly arcuate, glabrous.

  • Discussion

    Type. Neotype (designated by Proctor, Fl. L. Antill. 2: 185. 1977). Jamaica. Near Spanish Town, Sloane Herb. 1: 127 (BM).

    The acute-tipped pinnules with right-angle bases distinguish this taxon among the bipinnate, idioblastic species with large pinnules and hair-like scales on the blades. Putative hybrids with A. trichochlaenum, having malformed spores and large pinnae with papillate emergences on the indusia, have been found in Chiapas (Purpus 6864, NY, UC, US). See A. pulverulentum for discussion of hybrids with that species. Specimens of A. villosum from theWest Indies and some from Mesoamerica have the sori nearly continuous along the acroscopic pinna margins, while those from Mexico and most from Guatemala and Honduras have the sori interrupted into ca. 5– 7 units, each mostly 2–4 mm long.

  • Distribution

    Terrestrial in wet forests, tropical rain forests, seasonal evergreen forests, wooded slopes along streams, lower montane rain forests; 0–800 m. Mexico; Guat, Bel, Hond, Salv, Nic, CR, Pan; Gr & L Ant; Col, Ven, Trin, Tob, Ec, Peru, Braz.

    Mexico North America| Guatemala Central America| Belize Central America| Honduras Central America| El Salvador Central America| Nicaragua Central America| Costa Rica South America| Panama Central America| West Indies| Amazonas Colombia South America| Venezuela South America| Trinidad and Tobago South America| Amazonas Ecuador South America| Peru South America| Brazil South America|