Megalastrum pulverulentum (Poir.) A.R.Sm. & R.C.Moran

  • Family

    Dryopteridaceae (Pteridophyta)

  • Scientific Name

    Megalastrum pulverulentum (Poir.) A.R.Sm. & R.C.Moran

  • Primary Citation

    Amer. Fern J. 77(4): 129. 1987

  • Type Specimens

    Specimen 1: Not a type -- A. D. A. Fay 3845, verif. T. A. Zanoni, /11/2019

    Remarks: Earlier annotated as Megalastrum amplum R.C. Moran, J. Prado & Sundue, but name was never published. This specimen, Fay & Fay 3845 later included as M. pulverulentum (Poir.) A.R. Sm. & R. C. Moran, in Moran et al. in Amer. Fern J. 104(4): 201, 2014

  • Basionym

    Polypodium pulverulentum Poir.

  • Description

    by: R.C. Moran, J. Prado, and P.H. Labiak

    Lectotype: (designated by Proctor, 1985): Plumier, Traité Foug. Amér. 27, pl. 34, 1707, illustrating a plant from Hispaniola.

    Description: Leaves up to 4 m long; scales of the petiole bases 2-4 × 0.05 cm, linear-lanceolate, denticulate, light brown to golden; laminae up to 3 m long, 4-pinnate-pinnatisect at base, 3-pinnate-pinnatisect medially; basal pinnae ca. 1 m long, inequilateral; pinnules short-stalked, 35-70 cm long; pinna rachises glandular, pubescent, scaly, the glands ca. 0.1 mm long, spherical, sessile, yellowish, the scales 2-3 mm long, linear-lanceolate, dark brown, denticulate to ciliate (the cilia often darker than the body of the scale, especially towards the apex), non-bullate, the hairs 1.0-1.5 mm long, 5-8-celled, rachises adaxially glandular, densely pubescent, the hairs and glands like those abaxially; costules on the abaxial surface glandular, pubescent and scaly, the glands both sessile and stalked, ca. 0.1 mm long, spherical, sessile, yellowish, the hairs 1-2 mm long, 5-8-celled, spreading, the scales like those on the pinna rachises abaxially but smaller, ca. 1 mm long, the adaxial surface pubescent, the hairs 0.5-1.5 mm long, 3-6-celled, spreading; laminar tissue between veins pubescent and glandular on both surfaces, the hairs 1-2 mm long, 5-8-celled, the glands both sessile and stalked, rounded, yellowish; veins visible on both surfaces, abaxially glandular, sparsely pubescent, non-scaly, the hairs ca. 0.5-1.0 mm long, 3- or 4-celled, the scales ca. 0.3 mm long, uniseriate, appressed, reddish, adaxially non-glandular, sparsely pubescent, the hairs 0.4-1.0 mm long, 4-6-celled; laminar margins ciliate and glandular, the hairs 0.4-1.0 mm long, 3- or 4-celled, spreading, the glands few and stalked; indusia absent.

    Distribution and ecology: Guatemala, Costa Rica, Panama, Colombia, Jamaica, Haiti, Dominican Republic, Guadeloupe, Martinique, St. Vincent, Dominica, Saba; wet forests, shady ravines, 0-1600 m.

    Comments: Megalastrum pulverulentum is densely pubescent on both surfaces by long (1-2 mm) whitish hairs. The scales on the pinna rachises abaxially are more prominently toothed than any other species in the West Indies. The teeth are usually longest and darkest toward the apex of the scale. Yellowish glands are present on both surfaces and may be either sessile or stalked. Although difficult to describe, the laminar cutting is distinctive compared to other decompound species in the genus. This species and M. villosum are the largest species in the genus, with leaves to 4 m long. Megalastrum villosum differs by the presence of indusia and differences in laminar cutting. In the past, the name Megalastrum pulverulentum was applied widely to plants from Mexico to northern Argentina. Our unpublished studies suggest that this species in the wide sense is an aggregate of several different ones. The range given here is for the species in the strict sense.

  • Floras and Monographs

    Megalastrum pulverulentum (Poir.) A.R.Sm. & R.C.Moran: [Article] Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.