Pleopeltis angusta Humb. & Bonpl. ex Willd.
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Authority
Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.
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Family
Polypodiaceae
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Scientific Name
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Description
Species Description - Rhizomes long-creeping, 1.5–2 mm diam.; rhizome scales black with very narrow pale margins, 1.5–2 x 0.5–0.8 mm, comose, margins fimbriate; fronds distant, slightly dimorphic, fertile fronds narrower; stipes castaneous, 1/3–3/5 the frond length, glabrous, winged almost to base; blades deeply pinnatisect, 4–15 (–20) cm wide, with 1–5 pairs of lobes, these opposite to subopposite, linear, ascending, 4–12 cm x 1.5–7 mm; midribs (of rachises and costae) abaxially castaneous to black, prominent usually to blade and pinna apices; veins not readily visible; abaxial blade scales round, 0.3 mm wide, to ovate-lanceolate, 0.8–1 mm long, centers brown, margins denticulate, darker and more dissected around the sori; sori oblong, usually broader than the laminar space, with peltate soral scales 0.5–0.8 mm wide, centers brown-black, margins pale, fimbriate; 2n=68 (Guat), 74 (Oax, Guat), the latter number probably erroneous.
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Discussion
Polypodium angustum (Humb. & Bonpl. ex Willd.) Liebm., Mexic. Bregn. 186 (reprint 34). 1849. Type. Mexico. Near Ario, Humboldt & Bonpland s.n. (BWilld. 19729!; isotype P-Bonpl.!, photo US!).
Brazilian material referred to P. angusta belongs to the related P. pleopeltifolia (Raddi) Alston. Pleopeltis angusta, the type of the genus, differs from most Mexican species by the pinnatifid blades. In this character, it more closely resembles scaly species here treated in Polypodium. From P. fallax, which has pinnate-pinnatifid blades, P. angusta differs by the much larger fronds, thicker rhizomes, and blackened midribs.
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Distribution
Mexico North America| Brazil South America|