Polystichum acrostichoides (Michx.) Schott

  • Authority

    Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.

  • Family

    Dryopteridaceae

  • Scientific Name

    Polystichum acrostichoides (Michx.) Schott

  • Description

    Species Description - Caudices ca. 2 cm diam.; fronds mostly 30–70 cm long; stipes 8–30 cm long, 2–3 mm diam., mostly ca. 1/4–2/3 the blade length; stipe bases with numerous concolorous, tan, ovate to lanceolate scales 5–15 x 1–4 mm, with narrow teeth along margins; blades hemidimorphic, on a given frond the distal pinnae (8–25 pairs) fertile, constricted, proximal pinnae sterile, broader and longer, chartaceous, blades to ca. 50 x 12 cm, broadest near the bases, attenuate at the pinnatifid apices; rachises lacking buds, moderately scaly with ovate to hair-like toothed scales to 5 mm long; pinnae undivided, very gradually shortened distally, ca. 22–35 pairs, mostly 3–6 x 0.8–1 cm (excluding basal auricle), lanceate with a pronounced acroscopic, narrowly deltate auricle 3–8 mm long, otherwise serrate-spinulose along both margins, basiscopic bases cuneate, tips acute and spinulose; indument abaxially along costae and veins of scattered hair-like, twisted scales; sori indusiate, completely confluent at maturity, indusia tan to brown with darker brown centers, ca. 1–1.2 mm diam., subpersistent; 2n=82 (USA).

  • Discussion

    Nephrodium acrostichoides Michx., Fl. Bor.-Amer. 2: 267. 1803. Type. “Pensylvania, Carolina, Tennessee, Carol. Marit.” Michaux s.n. (P-MICH; see Morton, Amer. Fern J. 57: 172. 1967).

    This is closely related to, and can be confused in Mexico only with, P. munitum. It differs from that especially in the hemidimorphic blades, with the distal pinnae fertile and the proximal pinnae sterile. The stipe and rachis scales are also much lighter in color.

  • Distribution

    Terrestrial in pine-oak woods, in pine duff, among rocks; 1500–1750 m. Se Canada, e USA (west to Minn, Iowa, Kan, and e Tex); Mexico; naturalized in Europe.

    México Mexico North America| Canada North America| Minnesota United States of America North America| Iowa United States of America North America| Kansas United States of America North America| Texas United States of America North America|