Adiantum jordanii C.H.Müll.

  • 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 jordanii C.H.Müll.

  • Description

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    Species Description - Rhizomes short-creeping, 2–3 mm diam.; rhizome scales castaneous, 2–3.5 x 0.4–0.6 mm, margins entire; fronds clumped, 18–35(–45) cm, arching or pendent; stipes castaneous, lustrous, 9–20 x 1–1.5 mm, glabrous except at bases, not glaucous; blades ovate-lanceolate, 2–3-pinnate proximally, gradually tapered distally, 10–24 x 8–10 cm; rachises castaneous, glabrous; pinnae 4–6 compound pairs, alternate, proximal pinnae 1–2-pinnate; pinnulets flabellate to orbicular, usually broader than long, bases truncate or broadly cuneate, distal margins rounded, slightly incised, sterile margins serrulate, stalks 1–4 mm, with dark color ending +/- abruptly at pinnulet bases, non-articulate; veins free, forking, ending in marginal teeth; indument absent on both sides of blades; idioblasts absent; sori 2–5 per pinnulet, confined to distal margins; indusia 3–8(–10) mm long, oblong to linear, glabrous; 2n=60 (USA).

  • Discussion

    Type. U.S.A. California: Napa Valley, Jordan s.n. (KR?, STU?).

    This species is characterized by flabellate pinnulets with veins ending in teeth, 2–3(–5) sori per pinnulet, and color stopping more or less abruptly at the bases of pinnulets. It appears to be related to A. capillus-veneris and differs from that especially by the last character mentioned. It is a seasonal species, in California appearing with the winter (Nov–Apr) rains, and then drying and seemingly disappearing during the dry, nearly rainless summers. The name Adiantum emarginatum Hook. (Sp. Fil. 2: 39, t. 75A. 1851, non Bory ex Willd., 1810, which has as its type a plant from Mauritius) has often been used for this species, but Hooker did not intend to describe a new taxon. Subsequent authors (e.g., D. C. Eaton, Ferns N. Amer. 1: 285. 1879) adopted A. emarginatum in a new (and illegitimate) sense, applying it to plants from California. Hooker’s original figure probably does represent A. jordanii and was drawn from a collection that had been mislabeled, according to Eaton.

  • Distribution

    Terrestrial on moist ground in shade, on rocky banks, north slopes in chaparral, in damp shady gullies; 50– 500 m. USA (Calif, Ore); Mexico.

    Mexico North America| California United States of America North America| Oregon United States of America North America|