Pleopeltis

Plants epiphytic, on rock, or rarely terrestrial. Stems often long-creeping, usually branched, 1–2.5 mm diam., not whitish pruinose; scales bicolored with dark central region, round to ovate-lanceolate or subulate, clathrate toward center, glabrous or pubescent with reddish brown hairs, margins transparent, erose-denticulate to fringed-ciliate. Leaves monomorphic, widely spaced, not conspicuously narrowed at tip, to 25 cm. Petiole green to dark brown or black, flattened to terete, often grooved proximally and winged distally. Blade oblong-linear to deltate, simple and entire or deeply pinnatifid, not pectinate, with fewer than 25 pairs of segments, not glaucous, with conspicuous peltate scales on abaxial surface; rachis sparsely to densely scaly abaxially, glabrous to sparsely scaly adaxially; scales ovate-lanceolate to spheric, peltate, clathrate toward center. Segments (when present) linear to oblong; margins entire to crenulate; apex rounded. Venation mostly free or complexly anastomosing, with 1–several included veinlets in fertile areoles. Sori often confined to distal 1/2 of leaf, discrete or confluent, circular to oval when immature, borne at ends of single veins or at junction of several veinlets, in 1 row on either side of midrib; indument of ephemeral, peltate scales covering immature sori. Spores smooth with scattered spheric deposits or slightly papillate or verrucose. x = 34, 35, 37.

Distribution

Tropical regions, North America, Mexico, West Indies, Central America, South America, Africa, Asia in India.

Discussion

Pleopeltis is a neotropical genus of mostly epiphytic ferns. Its center of diversity is in southern Mexico and Central America. The genus is currently under revision, and preliminary data indicate that certain scaly-leaved species traditionally placed in the genus Polypodium are actually more closely related to Pleopeltis than they are to Polypodium. The two North American species of this scaly Polypodium group recently have been transferred to Pleopeltis (M. D. Windham 1993) and are similarly treated here.

Species ca. 50 (4 in the flora).

Selected References

Wendt, T. 1980. Notes on some Pleopeltis and Polypodium species of the Chihuahuan Desert Region. Amer. Fern J. 70: 5--11.

Windham, M. D. 1993. New taxa and nomenclatural changes in the North American fern flora. Contr. Univ. Michigan Herb. 19: 31--61. 1993.

Lower Taxa

Pleopeltis astrolepis, Pleopeltis polylepis, Pleopeltis polypodioides, Pleopeltis riograndensis

Key

1	Blades simple.	> 2
1	Blades deeply pinnatifid.	> 3
2	Scales on abaxial blade surface scattered, less than 0.5 mm wide, mostly roundish and deeply fringed (appearing stellate); petioles conspicuously flattened in cross section; sori oval to oblong, often confluent; stem scales mostly round, with numerous reddish brown hairs.	Pleopeltis astrolepis
2	Scales on abaxial blade surface dense and overlapping, 0.5–1 mm wide, broadly ovate-lanceolate with fringed-ciliate margins; petioles round in cross section; sori round to oval, discrete; stem scales lanceolate-attenuate, with only occasional hairs.	Pleopeltis polylepis var. erythrolepis
3	Mature blade scales distinctly bicolored with dark brown centers and broad tan to silvery gray transparent margins, clathrate only near point of attachment; petiole scales often overlapping, margins ± entire; sori deeply embossed, forming bumps on adaxial blade surface; stems usually 1–2 mm diam.	Pleopeltis polypodioides var. michauxiana
3	Mature blade scales not bicolored or occasionally with very narrow transparent margin, dark reddish brown, clathrate throughout with cell luminae large and clear; petiole scales rarely overlapping, margins denticulate to ciliate; sori not embossed, rarely visible on adaxial blade surface; stems usually 2–3 mm diam.	Pleopeltis riograndensis