Thelypteris tetragona (Sw.) Small
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Authority
Acevedo-Rodríguez, Pedro & collaborators. 1996. Flora of St. John, U.S. Virgin Islands. Mem. New York Bot. Gard. 78: 1-581.
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Family
Thelypteridaceae
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Scientific Name
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Description
Species Description - Terrestrial fern 40-90 cm tall. Rhizome short-creeping, woody, 7-9 mm thick, at apex bearing a small tuft of brown, lance-attenuate scales, these 2-3 mm long, minutely puberulous with forked hairs. Fronds somewhat dimorphic, the fertile ones longer, narrower, and more stiffly erect; stipes of fertile fronds to 50 cm long, minutely puberulous with erect, forked hairs. Blades ovate-oblong to triangular-oblong, 30-45 x 10-25 cm; rachis with minute forked and stellate hairs, the other vascular parts on both sides with simple hairs only; pinnae 6-12 pairs, linearoblong, sessile, acuminate to attenuate at apex, 1-3 cm broad, deeply lobed or pinnatifid, the fertile ones usually narrower than the sterile ones; segments oblong or triangular-oblong, mostly 4- 6 mm broad at base, the apex obtuse or obliquely acutish; veins 6-10 pairs per segment, the lowermost adjacent ones joined and sending an excurrent veinlet to the sinus; tissue thinly herbaceous, glabrous. Sori inframedial; indusium absent; sporangia deciduously setulose, the setae simple.
Distribution and Ecology - Occasional in moist forests. Bordeaux Mountain (A3191), Maho Bay Gut (A2104). Also on St. Croix, St. Thomas, and Tortola; Florida, Greater and Lesser Antilles, Trinidad, and continental tropical America from Mexico to Ecuador and Brazil
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Discussion
Polypodium subtetragonum Link, Hort. Berol. 2: 105. 1833. Dryopteris subtetragona (Link) Maxon in Britton & P. Wilson, Bot. Porto Rico 6: 473. 1926. Thelypteris subtetragona (Link) E.P. St. John, Amer. Fern J. 26: 44. 1936.
Polypodium smithianum Heward, Mag. Nat. Hist., n.s., 2: 459. 1838