Polypodium dispersum A.M.Evans
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Authority
Proctor, George R. 1989. Ferns of Puerto Rico and the Virgin Islands. Mem. New York Bot. Gard. 53: 1-389.
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Family
Polypodiaceae
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Scientific Name
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Description
Species Description - Rhizome short-creeping, 4-8 mm thick, clothed with lustrous red-brown, non-clathrate, narrowly deltate-acuminate scales 3-6 mm long, with entire or obscurely denticulate margins. Fronds closely crowded, mostly 20-50 cm long; stipes blackish, 6-18 cm long, narrowly marginate on both sides laterally, thinly pubemlous. Blades pectinate, narrowly deltate-oblong, 3-8.5 cm broad, narrowed to a short-acuminate apex, subtruncate to abruptly cuneate at base; rhachis blackish, pubemlous with minute, erect, pluricellular hairs, and bearing scattered, hastate, narrowly deltate scales on abaxial side, these dark red-brown with pale, expanded, fimbriate base; segments numerous, linear-ligulate, mostly spreading perpendicular to the rhachis, obtuse at apex, symmetrical at the adnate base; costae decunent onto rhachis, thinly pubemlous and with a few minute scales abaxially; veins often 2-forked, free; tissue firm-herbaceous, bearing scattered, very minute, whitish, pluricellular hairs on adaxial side. Sori medial, round or rarely oblong, with a few clavate paraphyses; sporangia often minutely setulose; spores 32 per sporangium. Plants apogamous, triploid, the gametophyte strap-shaped, without sex organs, proliferating directly to form sporophytes.
Distribution - Florida, Greater Antilles, Cayman Islands, Mexico to Honduras, in South America from Colombia and Venezuela to Bolivia and Brazil, and in the Galapagos Islands. Distribution in Puerto Rico. Of very wide occunence, and probably grows in most if not all municipios; recorded from Adjuntas, Aibonito, Arecibo, Barranquitas, Cayey, Ciales, Comerio, Fajardo, Isabela, Juana Diaz, Manati, Maricao, Ponce, Salinas, Trujillo Alto, Vega Alta, and Yauco. Habitat. On cliflfs, ledges, and boulders (calcareous or not), talus slopes, rocky banks, old stone walls, tree-tmnks, stumps and logs, and tenestrial in shaded humus, at low to upper middle elevations (sea-level-860 m ) , frequent or common.
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Discussion
Fig. 92.
Type. Evans 2008, from Pineola Grottoes, Citrus County, Rorida (MICH; isotypes TENN, US).
This remarkable asexual species is believed to have originated as a hybrid between Polypodium atrum Evans of southeastem Mexico, Guatemala, Belize, and Honduras, a diploid; and P. plumula of widespread distribution, a tetraploid. The spores are formed by mitosis (i.e., without a meiotic division) and are triploid; thus, the entire reproductive cycle is asexual and vegetative. The success of P. dispersum as a biological entity is shown by its wide geographic distribution (sometimes in areas where neither parent occurs) and its ability to adapt to a wide range of habitats.
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Distribution
Florida United States of America North America| Cayman Islands South America| México Mexico North America| Honduras Central America| South America| Amazonas Colombia South America| Bolivia South America| Brazil South America| Galápagos Islands Ecuador South America| Puerto Rico South America| Adjuntas Puerto Rico South America| Aibonito Puerto Rico South America| Barranquitas Puerto Rico South America| Cayey Puerto Rico South America| Ciales Puerto Rico South America| Comerío Puerto Rico South America| Fajardo Puerto Rico South America| Isabela Puerto Rico South America| Manatí Puerto Rico South America| Maricao Puerto Rico South America| Ponce Puerto Rico South America| Salinas Puerto Rico South America| Trujillo Alto Puerto Rico South America| Vega Alta Puerto Rico South America| Yauco Puerto Rico South America|