Thelypteris dentata

Thelypteris dentata (Forssk.) E.P. St. John
(Latin: dentatus, toothed, for the leaves which were described as “fronde pinnata, dentata” in the type description, though the “teeth” are actually the very small lobes of the pinnae = the ultimate leaf segments)

Local names: downy maiden fern, downy shield fern

Rhizomes short-creeping; leaves somewhat dimorphic, evergreen; petioles often purplish; leaf blades (25–)40–100 cm long, usually with more than 2 pairs of greatly reduced basal pinnae, the basal acroscopic segment of basal pinnae often auriculate; basal veins of adjacent ultimate leaf segments (= smallest subdivisions of leaf) united below the sinus between the segments, with the resulting single vein extending toward the sinus, the united portion usually 2–4 mm long; midveins of pinnae underneath (= abaxially) with mostly very short (0.3 mm or less long) hairs; sori round, medial to supramedial; indusia pubescent; 2n = 144 (Smith 1993a). Wooded slopes, damp woods, swamp hummocks, and along streams; Angelina (E. Boon s.n. 1934, TEX-LL), and Sabine (Correll 1956) cos. in the Pineywoods; also Harris Co. (Tharp 4279, TEX-LL; Turner et al. 2003) at the n margin of the Gulf Prairies and Marshes; naturalized in the se U.S. from SC (CLEMS, USCH) s to FL w to TX, also KY. Sporulating summer and fall. Native to the tropics and subtropics of Asia and Africa, but widely naturalized in the New World (Mexico, West Indies, Central and South America). This species has apparently spread rapidly in the New World; Smith (1993a) noted that prior to 1900 it was “virtually unknown in the Americas.” [Christella dentate (Forssk.) Bronsey & Jermy, Dryopteris dentate (Forssk.) C. Chr., Polypodium dentatum Forssk.] This introduced species “is becoming one of the most common ferns in many areas of the Neotropics” (Mickel & Smith 2004).

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