Polystichum platyphyllum (Willd.) C.Presl

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 platyphyllum (Willd.) C.Presl

Description

Species Description - Caudices 1–3 cm diam.; fronds mostly (32–)50–80(–110) cm long; stipes (10–)25–50 cm long, 2–3 mm diam., half to nearly equaling the blade length; stipe bases with scales concolorous, tan to brown, ovate to lanceolate, larger ones 5–10 x 1–3 mm, margins with long, flaccid, twisted cilia, also with hair-like, denticulate scales 2–4 x 0.5–0.8 mm, distally with scattered hair-like scales; blades chartaceous, (20–)35–60(–70) x (8–)20–30 cm, broadest at the bases or nearly so, very gradually attenuate at apices and generally with many (to12 pairs) simple pinnae similar to pinnules of proximal pinnae; rachises with dense to scattered, twisted, ± entire, hair-like, eciliate scales 1–7 mm long, nearly always bearing a small scaly bud(s) at the base of a distal pinna; pinnae pinnate, ca. 25–35 pairs, (5–)10–16 x (1.5–)3–4.5 cm, pinnules planar, oblong-rhomboid, each with a small, deltate, acroscopic auricle, then crenate or crenately lobed along the acroscopic margin, basiscopic margin ± entire to crenulate, apices rounded with aristate tips; indument abaxially along costae, costules, and veins of scattered, hair-like scales; sori exindusiate, not confluent at maturity; 2n=82 (Chis), 164 (Parag).

Discussion

Aspidium platyphyllum Willd., Sp. Pl., ed. 4, 5(1): 255. 1810. Phegopteris platyphylla (Willd.) Mett., Abh. Senckenberg. Naturf. Ges. 2: 296. 1858. Type. Venezuela. Caracas, Bredemeyer s.n. (B-Willd. 19789).

Unverified, Doubtful, or Mistaken Reports. Gro (Campos 1663, FCME, cited by Lorea-Herna´ndez & Vela´zquez M., 1998, but not verified). This exindusiate taxon bears a small bud (occasionally more than one bud) in the axil of a distal pinna, which distinguishes it from all other Mexican congeners. Its closest relatives are P. polystichiforme (Fe´e) Maxon from the Greater Antilles, and a host of South American exindusiate species, most numerous in southern Brazil. Polystichum platyphyllum is the most wide-ranging species of the genus in Mexico and is probably a species complex over its range, as evidenced by diploid and tetraploid chromosome number reports. Mu¨nch 96 (DS), from Chiapas, is problematic. Nothing like it has since been collected in Chiapas, Mexico, Mesoamerica, or the Antilles, as far as we know. The blade on the right side of this sheet resembles most closely Polystichum sellowianum C. Presl, from Rio de Janeiro, Brazil, particularly Brade 8579 and Brade 20726 (both UC). It is also very similar to Glaziou 4667 (UC), labeled P. lanosum Fe´e, also from Rio de Janeiro (see Smith, 1981: 199); the two may be synonymous, with P. sellowianum having priority. This taxon differs from P. platyphyllum in lacking a rachis bud (all specimens seen) and in the very distinctive, large, rhombic-ovate pinnules having a deltate auricle at the acroscopic base. The separate blade fragment (three pinnae) on the left side of Mu¨nch 96 seems different from the plant on the right, and could be P. platyphyllum; this left-hand specimen has decidedly more denticulate costal and rachis scales than the plant on the right. If we are correct in suspecting that the plant on the right is conspecific with P. sellowianum (and P. lanosum), and the specimen is correctly labeled as to origin, then it would be a most remarkable disjunct distribution. It seems more likely, however, that it is mislabeled, a circumstance that is known to have happened with other Mexican/Brazilian ferns, especially in specimens emanating from Paris, as this one likely did (for other suspected examples of false labeling, see, e.g., Yatskievych, G. 1996. A revision of the fern genus Phanerophlebia (Dryopteridaceae), Ann. Missouri Bot. Gard. 83: 191, 1996; also Reineck s.n. (UC), Thelypteris puberula (Baker) C. V. Morton var. puberula, labeled from Brazil, Rio Grande do Sul, a specimen probably collected in Mexico).

Distribution

Terrestrial in wet montane forests; 750–1600 m. Mexico; Hond, Nic, CR, Pan; Jam; Col, Ven, Ec, Peru, Braz, Bol, Parag, nw Arg.

Mexico North America| Argentina South America| Paraguay South America| Bolivia South America| Brazil South America| Peru South America| Amazonas Ecuador South America| Venezuela South America| Colombia South America| Jamaica South America| Panama Central America| Costa Rica South America| Nicaragua Central America| Honduras Central America|