Pecluma
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Authority
Mickel, John T. & Smith, Alan R. 2004. The pteridophytes of Mexico. Mem. New York Bot. Gard. 88: 1-1054.
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Family
Polypodiaceae
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Scientific Name
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Description
Genus Description - Mostly epiphytic, less often epipetric or terrestrial; rhizomes long- to often short-creeping, unbranched, never glaucous, sometimes proliferous by root buds; rhizome scales concolorous to bicolorous, non-clathrate, basally attached, surfaces glabrous or hairy (comose), margins entire, toothed, or short-ciliate; fronds monomorphic, distant (ca. 1.5 cm apart) or clumped; stipes black to reddish brown, rarely lighter in color, terete (never channeled), articulate, phyllopodia 1-2 mm long; blades pinnatisect with numerous linear or narrowly deltate pinnae, bases attenuate to truncate, pinnae curling in response to drought, sometimes with scattered to numerous scales along the axes; indument adaxially on rachises, costae, and sometimes laminae between veins of mostly septate hairs, abaxially with similar sometimes longer hairs on rachises and costae, laminae between veins often with inconspicuous appressed, septate hairs 0.1-0.2 mm; veins free, rarely casually anastomosing, simple or 1-4-forked; sori round, exindusiate, terminal on first acroscopic veinlet, in single rows on each side of costae; soral paraphyses simple or branched, multicellular, sometimes clavate at the tips; sporangia glabrous or with 1-3-celled hairs (0-5 per sporangium) on the capsules; spores yellowish to whitish, bilateral (globose in an apogamous species, P. dispersa), surfaces verrucate to tuberculate with SEM magnification, seemingly smooth under the light microscope; x= 37.
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Discussion
Type: Pecluma pectinata (L.) M. G. Price [ Polypodium pectinatum
Pecluma comprises about 28 species, all neotropical. Closest affinities appear to be with those species of Polypodium that lack scales on the blades, particularly the group of free-veined species related to P. hartwegianum, P. chiapense, and P. diplotrichum. The species of Pecluma (as the “Polypodium pectinatumplumula complex”) were revised by Evans (1968) and later segregated as a genus separate from Polypodium by Price (1983). Some species in this group have sometimes been included among the grammitid ferns, in Ctenopteris (e.g., by Copeland, 1955), but the similarity is only superficial. Pecluma differs from Polypodium s.str. in having often short-creepingt, non-branching, nonglaucous rhizomes, proliferous roots, non-clathrate basally attached rhizome scales, terete stipes and rachises, and pectinate fronds. From the grammitid genera, Pecluma differs by having bilateral, non-green spores, two-rowed sporangial stalks, usually comose rhizome scales, and hyaline to yellowish (vs. maroon), obviously septate and often crispate hairs. A peculiar hair type, called “ctenoid” by Evans (1968), is found along the stipes and rachises of several species, most commonly in P. consimilis, P. divaricata, and P. ptilodon. These hairs consist of an arching or appressed axis of about four cells, each with a 1–2-celled lateral branch, all arising from one side of the axis, producing a comb-like trichome.