Thelypteris dentata (Forssk.) E.P.St.John

  • Authority

    Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.

  • Family

    Thelypteridaceae

  • Scientific Name

    Thelypteris dentata (Forssk.) E.P.St.John

  • Description

    Species Description - Rhizome short-creeping; fronds somewhat dimorphic, the sterile shorter and with fewer, wider pinnae than the fertile; stipe darkened, often purplish, 15-45 cm long, 3-5 mm diam., paleate at base; lamina herbaceous or chartaceous, (24-)40-92 cm long, tapering evenly toward the pinnatifid apex; largest pinnae 7-17 cm long, 1.1-2.7 cm wide, incised 0.5-0.8 of the way to costae; lower (1-)2-6 pairs of pinnae reduced, auricled at the superior base, auricles entire or crenate; veins 610 pairs per segment, the basal pair from adjacent segments united at an obtuse angle below sinus with an excurrent veinlet 2-4 mm long to sinus; costae, costules, and leaf tissue pubescent below, the hairs dense, uniformly short, 0.1-0.2 mm long, occasionally with scattered longer hairs, above with hairs longer and stouter except on leaf tissue; glands usually absent on blades; indusia uniformly pubescent, hairs 0.1-0.2 mm long; n = 72.

  • Discussion

    Polypodium dentatum Forsskål, Fl. aegypt.-arab. 185. 1775. Dryopteris dentata (Forsskål) Christensen, Kongel. Danske Vidensk. Selsk. Skr., Naturvidensk. Afd. VIII, 6: 24. 1920. Cyclosorus dentatus (Forsskål) Ching, Bull. Fan Mem. Inst. Biol. 8:206. 1938. Type. Yemen. Forsskål s.n. (C!). Aspidium molle Swartz, J. Bot. (Schrader) 1800(2): 34. 1801. Dryopteris mollis (Swartz) Hieronymus, Hedwigia 46: 348. 1907. Type. Cultivated specimen (W!). More complete synonymy cited in A. R. Smith (1971, 1983). Thelypteris dentata differs from most other members of subg. Cyclosorus in Oaxaca by the veins united below the sinus. From T. hispidula, its closest relative, it differs by the uniformly short hairs 0.1-0.2 mm long on the costae below (hairs 0.3-0.8 mm long and of variable length in T. hispidula), by the short-creeping rhizome, and by the usually darkened stipe and rachis. This species is native to the Old World but introduced in the New World. It is becoming one of the most common ferns in many areas of the neotropics. The first collection from Oaxaca was in 1967.

  • Distribution

    Along trails, roadsides, and banks, and in cut-over woods, in shade or partial sun; Ixtlán, Teotitlán, Tuxtepec; 50-1600 m. Mexico (Ver, Oax, Chis); se US; Guat to Pan; WI, Trin; Ven & Col, s to Peru, Braz, Arg; Old World tropics and subtropics.

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