Adiantum seemannii 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 seemannii Hook.

  • Description

    Species Description - Rhizomes short-creeping, rather compact, 5–10 mm diam.; rhizome scales castaneous, concolorous, entire to minutely denticulate; fronds clumped, mostly 30–70 cm long, arching; stipes atropurpureous to black, to 45 cm x 3 mm, glabrous except at bases; blades ovate to deltate, 1-pinnate or some specimens 2- pinnate proximally, each blade with a +/- conform terminal pinna; rachises atropurpureous to black, glabrous; pinnae 1–4 pairs, broadly ovate, mostly 5–10 x 2.5–6 cm, rounded at bases, acuminate at apices, serrate (sterile) to entire (fertile), with stalks 1–3 cm long, stalk color stopping abruptly at pinna bases, pinnae not articulate; pinnules absent on pinnae, or the proximal pinna pair 1-pinnate; veins free, forking, ending in sharp teeth on sterile pinnae/pinnules; indument absent on both surfaces, blades often glaucous abaxially; idioblasts present on both blade surfaces, more conspicuous adaxially; sori linear, usually interrupted (but contiguous) on both acroscopic and basiscopic margins of pinnae or pinnules; indusia mostly 5–20 mm long, especially near bases of pinnae/pinnules, glabrous.

  • Discussion

    Type. Panama. Veraguas: San Lorenzo, Seemann 1124 (K! photo UC!).

    Adiantum seemannii is readily distinguished from congeners in Mexico by the 1-pinnate blades, relatively few lateral pinnae (1–4 pairs), and large, ovate pinnae 5–10 cm long. It is related to species in South America, e.g., A. platyphyllum Sw., from Ecuador to Bolivia and southern Brazil.

  • Distribution

    Terrestrial in lowland and lower montane forests on steep rocky slopes; 200–450 m. Mexico; Guat, Hond, Nic, CR, Pan; w Col.

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