Adiantum wilsonii Hook.

  • 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 wilsonii Hook.

  • Description

    Species Description - Rhizomes short- to long-creeping, 2–3 mm diam.; rhizome scales brown, concolorous, margins entire to minutely denticulate; fronds 5–10 mm apart, mostly 20–50 cm long, arching; stipes atropurpureous to blackish, 15–31 cm x 1.5–2.5 mm diam., sparsely filiform-scaly to hairy, often glabrescent; blades broadly ovate to deltate, 1-pinnate, each with a subsimilar but often slightly broader terminal pinna (juvenile fronds sometimes cordate); rachises atropurpureous, sparsely to moderately filiformscaly and hairy; pinnae 1–3(–6) pairs, alternate, entire (sterile serrulate), ovate-lanceolate, rounded or subcordate at bases, acute at tips, ca. 6–10 x 2.5–4 cm, costae medial, distinct, stalks 2–6 mm long, stalk color passing into the pinna bases, nonarticulate; veins forking, anastomosing toward pinna margins, ending in small teeth; indument absent adaxially, abaxially of scattered hair-like scales and hairs on the costae and laminar tissue near the costae; idioblasts present; sori continuous along the acroscopic and basiscopic pinna margins, pinna apices sterile; indusia to 12 cm long, linear, glabrous.

  • Discussion

    Type. Jamaica. Near Bath, Wilson s.n. (K-3 sheets, photos UC!, US).

    This was treated by Smith (1981) under A. dolosum Kunze [= A. asperum (Poir.) Desv.], a very closely related species from the Guianas. Adiantum asperum differs primarily by the greater number of narrower lateral pinnae and the dark color of the pinna stalks not entering the costae abaxially. In Mexico, A. wilsonii is most similar to A. macrophyllum, but the resemblances are not indicative of a close relationship. Rather, A. wilsonii is related to several anastomosing-veined South American species, including A. asperum, A. phyllitidis J. Sm., from the Guianas to Colombia, and A. poeppigianum (Kuhn) Hieron., from Peru. This group comprises the segregate genus Hewardia.

  • Distribution

    Terrestrial in lowland and lower montane forests; 0-800 m. Mexico; Guat, Bel, Hond, Nic, CR, Pan; Gr Ant; w Col, Ec.

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