Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.
Dryopteridaceae
Species Description - Similar to Megalastrum subincisum except: plants with erect trunks to 0.7 m tall; fronds 2–5 m long; blades 4-pinnatepinnatifid at bases; indument abaxially on costae, costules, and ultimate segment midveins of soft, lax, hyaline hairs 0.8–1 mm long; costal scales with longer teeth ca. 0.1 mm; 2n=82 (Jam.).
Ctenitis pulverulenta (Poir.) Copel., Gen. Fil. 124. 1947. Polypodium pulverulentum Poir. in Lamarck, Encycl. 5: 555. 1804. Dryopteris pulverulenta (Poir.) C. Chr. in Urban, Symb. Antill. 9: 305. 1925. Type. Plumier, Traite´ Foug. Ame´r. 27, pl. 34, 1705, illustrating a plant from Hispaniola. Polypodium karstenianum Klotzsch, Linnaea 20: 390. 1847. Dryopteris karsteniana (Klotzsch) Hieron., Hedwigia 46: 348. 1907. Ctenitis karsteniana (Klotzsch) Vareschi, Fl. Venez. 1(1): 405. 1969. Type. Venezuela. Karsten II. 3 (B). ?Phegopteris hirsuta Fe´e, Me´m. Foug. 5: 248. 1852. Type. Mexico. Funck & Schlim 975 (P?). Dryopteris karsteniana (Klotzsch) Hieron.var. heydei C. Chr., Kongel. Danske Vidensk. Selsk. Skr., Naturvidensk. Math. Afd., ser. 8, 6: 77. 1920. Ctenitis pulverulenta (Poir.) Copel. var. heydei (C. Chr.) Stolze, Amer. Fern J. 67: 43. 1977. Megalastrum pulverulentum (Poir.) A. R. Sm. & R. C. Moran var. heydei (C. Chr.) A. R. Sm. & R. C. Moran, Amer. Fern. J. 77: 129. 1987. Type. Guatemala. Santa Rosa: Ri´o de los Esclavos, Heyde & Lux s.n. [Donn. Sm. 3249 p.p.] (US!; isotypes GH, MO).
This is the largest species in the genus, with the fronds as long as or longer than many tree ferns. Specimens of Ventura 399 have fronds to 4.6 m long. Smith et al. 4139 (US), from Edo. Puebla, was noted as having a trunk two feet tall, an unusual condition in the genus as a whole, but possibly normal for this species.
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