Polystichum ordinatum (Kunze) Liebm.
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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
Dryopteridaceae
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Scientific Name
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Description
Species Description - Caudices ca. 2–4 cm diam.; fronds mostly 45–150+ cm long; stipes 10–35(–50) cm long, 2–8(–12) mm diam., ca. 1/4 to nearly equaling the blade length; stipe bases with lanceate, ascending scales 7–12 x 1–2(–3) mm, scales entire to sparsely ciliate, thickened at bases, usually discordantly bicolorous, with a narrow, dark brown, thickened central band and lighter tan margins, scales of the distal part of stipes concolorous and light brown; blades thin-chartaceous, ca. 30–60(–90) x 10–28 cm, proximal 2–5(–8) pairs of pinnae reduced to ca. 0.3–0.8 the length of the longest pinnae, attenuate at apices; rachises lacking buds, with tan hair-like eciliate scales to 5 mm long; pinnae pinnatepinnatisect, ca. 20–25(–36) pairs, 5–20 x 1.5–2.5 cm, pinnules serrately incised to pinnatifid, some pinnules with a ± free obovate lobe at base, both margins and tips spinulose; indument abaxially along costae and costules of fibrillose scales; sori indusiate, not confluent at maturity, indusia tan to brownish, relatively small, apparently reniform or reniform-spatulate, fugacious, 0.2–0.5 mm diam.
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Discussion
Aspidium ordinatum Kunze, Linnaea 18: 347. 1844. Type. Mexico. Leibold s.n. [Leib. Verz. No. 39] (LZ, destroyed; presumed isotypes B!, K!, P!-6 sheets, NY!; frag. US!).
Polystichum bicolor A. R. Sm., Proc. Calif. Acad. Sci., ser. 4, 40: 223, f. 6E- G. 1975. Type. Mexico. Chiapas: Mpio. Tenejapa, Colonia ‘Ach’lum, Ton 1987 (DS!; isotype MEXU!).
Polystichum ordinatum differs from P. hartwegii, P. fournieri, and P. muricatum, all close relatives, in its lanceolate, usually rather decidedly bicolorous scales with thickened bases, reduced proximal pinnae, and small indusia mostly 0.2–0.5 mm diam. In some specimens seen, the indusia are lost early in development, and the indusia that are seen appear to be reniform or spatulate-reniform, rather than truly peltate as found in other Mexican indusiate species. This is especially evident in a series of specimens collected from near Acajete, in Edo. Veracruz. The closest relative appears to be P. hartwegii, and some specimens are difficult to place in one or the other species. The stipe base scales are sometimes abraded with age, and show clearly the stoutness of the scale at the point of attachment, leaving the stipes almost muricate. As stated earlier (Smith, 1981), the name P. ordinatum has been too widely applied, and we are still uncertain that we have applied it correctly to the taxon circumscribed herein. The type and most collections cited here have several pairs of shortened proximal pinnae, the lowermost about half or less the length of the longest ones. Other Mexican polystichums may have the proximal pinnae slightly reduced, but generally only a single pair, and not shortened to the extent found in P. ordinatum. Polystichum ordinatum is also quite variable, and divisible into two elements: 1) very large-fronded specimens with small, seemingly peltate indusia and thick-chartaceous to subcoriaceous blade texture; and 2) small-fronded plants with reniform indusia and thin-textured blades. The taxonomic status of these two variants needs clarification. The large-fronded variant appears to be common in southern Veracruz in the vicinity of Xalapa, but elsewhere it is rather uncommon. Mickel 4122 (UC) is a mixture of P. erythrosorum and P. ordinatum, and shows the value of mixed collections. Such gatherings call attention to “genus communities,” wherein the differences between two closely related species are maintained.
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Distribution
Terrestrial in wet forest; 1200–2800 m. Mexico; Guat.
Mexico North America| Guatemala Central America|