Adiantum poiretii Wikstr.

  • 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 poiretii Wikstr.

  • Description

    Species Description - Rhizomes short- to usually long-creeping, 1.5–3(–4) mm diam.; rhizome scales castaneous, lanceolate, 3–4 x 0.5–0.8 mm, entire to short-ciliate; fronds distant, (10–)20–60(–75) cm long, arching; stipes ca. 1/4–1/2 the frond length, 7–35 cm x 0.8–2 mm, castaneous to atropurpureous, glabrous except at bases; blades ovate-deltate, (2–)3–4-pinnate proximally, (5–)15–45 x 4–35 cm, gradually tapering to apices; rachises castaneous to atropurpureous, glabrous; pinnae 3–9 pairs, alternate, tapering at apices; pinnulets orbicular to flabellate, 5–8 x 5–10(–15) mm, mostly symmetrical, not articulate, cuneate or truncate at bases, entire or with a few teeth distally, stalk color passing into pinnulet bases and often into veins, non-articulate; veins free, forking, ending in sinuses of sterile pinnulets; indument absent on both surfaces, or glaucous abaxially; idioblasts absent; sori mostly 3–8 per pinnulet, confined to distal margins, yellow farina mixed with sporangia; indusia 1–3 mm long, lunate to reniform or roundreniform, glabrous; 2n=114 (Africa).

  • Discussion

    Type. Tristan da Cunha, Petit-Thouars s.n. (P-JU 1427!).

    Adiantum thalictroides Willd. ex Schltdl., Adumbr. Pl. 5: 53. 1832. Type. Mauritius, Petit-Thouars s.n. (B-Willd. 20101!, BR! photo ex P). Adiantum pellucidum M. Martens & Galeotti, Me´m. Foug. Mexique 72. 1842. Type. Mexico. Oaxaca: Tanetze & Talea [Llano Verde; isotype], Galeotti 6461 (BR!, photo P! ex BR, photo US! ex BR; isotypes BR!, C!, K!, LE!, P!). One of the specimens from BR is A. concinnum. Adiantum gratum Fe´e, Me´m. Foug. 5: 119. 1852. Type. Mexico. Oaxaca: near Nolasco, Galeotti 6542 (P? not found) [perhaps 6562 (BR!, K!)]. Unverified, Doubtful, or Mistaken Reports. Nay (reported by Mickel & Beitel, 1988, and Mickel, 1992, but not verified; Calzada 18618, MEXU, US, determined as this in various herbaria, is A. tricholepis). Tam (reported by Mickel & Beitel, 1988, and Mickel, 1992, but not verified; also reported by Sharp, 1954, from Rancho del Cielo, but not verified). Tres Mari´as (Ferris 5652, DS, cited by Lenz, 1995, but not verified). This species and A. andicola are by far the commonest species of Adiantum in Mexico at middle to high elevations, and A. poiretii is especially common in and around the Valley of Mexico. Material from Tristan da Cunha is sometimes considered distinct, in which case all other material is called A. thalictroides Schltdl. Adiantum poiretii is distinguished from A. raddianum by the golden brown scales, usually longer-creeping rhizomes, smaller pinnulets, and yellow farina in the sori. Specimens from northwestern Mexico and Baja California Sur often show a pronounced dimorphism, with the sterile fronds having much larger pinnulets, nearly twice as large as the fertile ones. Given only a sterile frond, it is easy to mistake this species for A. braunii, which may occur in the same general area.

  • Distribution

    Terrestrial, higher elevations, pine-oak woods, oak woodlands with tropical deciduous forest elements, near streams; 800–3150 m. Mexico; Guat, Hond, Salv, Nic, CR, Pan; Cuba?, Hisp; Col, Ven, Ec, Peru, Bol, Chile, Arg; Old World.

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