Adiantum patens Willd.

  • 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 patens Willd.

  • Description

    Species Description - Rhizomes short-creeping, 3–5 mm diam.; rhizome scales light brown, ciliate-fimbriate, 2–3 x 0.8–1 mm; fronds clumped, 20– 45(–70) cm long, laxly arching; stipes castaneous to atropurpureous, 12–40 cm x 1–2(–3) mm, 1/2–2/3 the frond length, glabrous except at bases; blades imparipedate, almost round in outline, to 30 x 30 cm, the two proximal pinnae alternate, each appearing 2–3-forked by virtue of unequal basiscopic branching; rachises castaneous, with dense, branched whitish hairs 0.1 mm long; pinnae a single lateral pair plus a terminal one, the lateral ones to 20 cm long, unequally basiscopically branched 2–3 times, the terminal one 1-pinnate, to 25 cm long; pinnulets oblong, roundedto truncate at tips, shallowly lobed to crenate on acroscopic and distal margins, entire on basiscopic margins, subsessile with stalks less than 1 mm long, stalk color passing into pinnulet bases, non-articulate; veins free, forking, ending at the cartilaginous margins; indument on both surfaces of scattered glandular, septate hairs 0.2–1 mm long on veins; idioblasts absent; sori to 10 per pinnulet along acroscopic and distal margins, absent on basiscopic margins; indusia 1–1.5 mm long, lunate to reniform or round-reniform, glabrous.

    Distribution and Ecology - Terrestrial on road banks and open woods, pineoak forests; 200–1900(–2100) m. Mexico; Guat, Hond, Salv, CR; Col, Ven, Ec, Peru, Bol; Africa (subsp. oatesii)

  • Discussion

    Type. Venezuela. Caracas, Bredemeyer s.n. (B-Willd. 20078!, photo GH!, frag. NY!; isotype W).

    Adiantum lobatum C. Presl, Reliq. Haenk. 1(1): 62, t. 10, fig 5. 1825. Type. Mexico. s. coll. [presumably Ne´e] s.n., (PR). This species is extremely common on the Pacific slopes in Mexico (e.g., over a hundred collections have been seen from Nayarit and Jalisco alone) but absent elsewhere in the country. The seemingly pedate branching of the fronds and the minute, branching rachis hairs distinguish this species from all others. Although superficially similar to A. aleuticum, which has similar blade architecture, the closest relatives appear to be A. galeottianum and A. shepherdii, which see. A closely related subspecies occurs in Africa, subsp. oatesii (Baker) Schelpe.

  • Distribution

    Mexico North America|