Polystichum Roth, nom. cons.,
Descripción
Rhizomes ascending to erect, short, compact, usually stout, heavily scaly, with many old leaf bases forming stout caudices; fronds monomorphic, medium-sized to large, mostly 50–150 cm long, crown-forming; stipes usually stramineous to tan, usually densely scaly, at least at their bases, scales lanceate to broadly ovate, subentire to erose or denticulate, sometimes also ciliate with long, thin hair-like processes; blades narrowly to broadly deltate, 1–2-pinnate, rarely 3-pinnate, anadromous, some species proliferous with rachis bud near blade apices or in pinna axils; rachises and costae grooved adaxially, the grooves confluent from one axis to the next; segments thin to commonly subcoriaceous or coriaceous, usually with marginal spinulose teeth, glabrous to scaly abaxially, especially on veins and axes, lacking acicular hairs; veins free, forking; sori abaxial, round, typically with peltate indusia, or indusia absent; spores bilateral, with a winged or strongly folded, sometime echinate and/or fenestrate perispore; x=41.
A
A
Forma de vida
Epipétrica, TerrestreA
Distribución
México (país) Nativo y no endémicoA
Categoría IUCN
No incluidaB
Categoría NOM-059-SEMARNAT-2010
No incluidaC
Discusión taxonómica
Polystichum is a largely temperate genus of nearly 200 species, with most of the tropical species at higher elevations, although a few occur at middle elevations in wet forests. The genus is difficult to circumscribe and distinguish clearly from Cyrtomium and Phanerophlebia, and a broad view of Polystichum could include both segregates. Recent phylogenetic work by Little and Barrington (2003) indicates that Phanerophlebia is sister to Polystichum s.l. (including the segregrate genera Cyrtomium and Cyrtomidictyum in Asia), but that Polystichum s.str. can be made monophyletic by the recognition of both of these Asian segregates. Polystichum is usually distinguished by its peltate indusia, 2-pinnate blades, and free veins, but many exindusiate and 1-pinnate species are known, even among the Mexican taxa.
Of the Mexican species, about half are well defined, mostly allopatric with respect to congeners in Mexico, and rather restricted or rare in their distribution. These include nearly all of the exindusiate species (P. mickelii, P. orbiculatum, P. platyphyllum, P. schizophyllum, and P. speciosissimum), as well as the 1-pinnate ones (P. acrostichoides, P. muenchii, P. munitum). The remaining ten species are more difficult to distinguish from each other, and very likely they have incompletely diverged or have come into contact again after being allopatric previously. Mostly these appear to be diploids, but there is evidence that some populations are tetraploid, as judged by the large spores of some herbarium specimens and a few chromosome counts. The central and perhaps most variable species seems to be P. hartwegii, which is also the most widely distributed and common of the Mexican species.
The species of Polystichum appear difficult to define, in part, because of probable hybridization. In tropical regions, this is not very well documented, except for the studies of Barrington (1985a, 1985b), but in temperate regions, hybridization is well studied in northwestern North America, Europe, and Japan. Extensive work needs to be done on the morphological diversity and ecology of individual populations for a better understanding of the species and their dynamics in tropical America. It is also not likely that a fuller understanding of the systematics can be achieved until modern cytotaxonomic and isozymic studies have been done. Additional species may well be recognized once proper studies can be made, and we allude to some interesting unnamed collections at the end of this treatment; it would, however, be premature to describe them now because of the general taxonomic confusion in the genus and also the paucity of collections.
The genus Rumohra, sometimes considered to be related to Polystichum and similar in its peltate indusia, is known to us from a single Mexican collection of Rumohra adiantiformis (G. Forst) Ching: Jalisco, Los Guayabos, “alterado, en una huerta, lugar húmedo,” 1500 m, Pilar Mones U. 18218 (UC). It is nuclear from the label whether this species, often cultivated around the world, has become established and is reproducing on its own or not. It is generally considered to be a circumaustral, polymorphic species, and is also considered native to much of South America (e.g., Venezuela, Peru, Brazil, Bolivia, Chile, Argentina), S. Africa, Madagascar, Australia, and New Zealand. It is also apparently indigenous to the Greater Antilles, but is unknown from Mesoamerica. From Polystichum, Rumohra differs in its adaxially flattened (vs. sulcate) costae, long-creeping dorsiventral rhizomes (vs. short-creeping to suberect, radial), and apically rounded to acute (vs. aristate) ultimate segments.
Hybrids and Problematic Specimens
Here we list and discuss a number of problematic specimens, both those that are putative hybrids (parentage uncertain) andthose that cannot be placed satisfactorily in any species recognized in this treatment at this time.
Breedlove 22605 (DS, MEXU), Chis. Smith (1981) identified this as P. fournieri, with a query. It is not that, but probably a hybrid of uncertain parentage, perhaps involving P. distans. The spores are malformed and very irregular in size and shape.
Mickel 4674 (NY, UC), Oax. This was originally cited as P. hartwegii by Mickel and Beitel (1988), but Barrington annotated it in 1993 as Polystichums P. nov. , aff. P. fournieri. We agree that it is not P. hartwegii and cannot match it with any known species. It differs from P. fournieri in having smaller indusia; perhaps its closest affinity is with P. turrialbae.
Mickel 5310 (NY, UC), Oax. This is peculiar in the exindusiate sori and very reduced proximal pinnae, lowermost ca. 5 pairs gradually shortened, the most basal ones ca. 1 cm long; fronds ca. 45 cm long; blades ca. 35 X 15 cm; larger pinnules pinnatifid, ca. 10 X 5 mm; stipe base scales lanceate, to ca. 8 X 1.5 mm, brownish, entire, not particularly distinctive. We suspect that this specimen represents an undescribed species but are uncertain as to its affinities. Mickel and Beitel (1988) cited it as P. ordinatum, no doubt because of the reduced proximal pinnae, but it does not appear very closely related to that.
Mohr s.n., 1857 (US), Ver. Although the blade is incomplete, this appears to have several pairs of reduced proximal pinnae. It might be P. ordinatum, but the indusia are very large, to 1.8 mm diam. The pinnules are relatively undivided, and so approach those of P. rachichlaena, but we do not otherwise know that species from Edo. Veracruz.
Pringle 5588 (MEXU, US), Ver. This appears to match Mohr s.n., discussed above, with very large indusia and reduced proximal pinnae.
Tenorio 18554 (MEXU–3 sheets), Oax. Most likely this represents an undescribed species, probably confined to high elevations (2800 m). The stipe base scales are most similar to those of P. alfaroi, but concolorous and light orange-brown without a darkened middle band. Pinnules are ± entire and spreading (thus differing from P. alfaroi), with a deltate basal auricle, and coriaceous with revolute margins, similar to some specimens of P. distans (which has completely different stipe base scales). We are unable to suggest its nearest ally.
Unplaced Names
Polystichum aculeatum (L.) Roth α incisum Fée, Mém. Foug. 8: 100. 1857. Type. Mexico. “Cordoba des Mexicains,” Schaffner 250 (not located).
Polystichum aculeatum (L.) Roth ß gracile Fée, Mém. Foug. 8: 100. 1857. Type. Mexico. “Guatimalpan et San Agustin,” Schaffner 315 (not located).
Polystichum aculeatum (L.) Roth γ distans Fée, Mém. Foug. 8: 100. 1857. Type. Mexico, “Totutla des Mexicains,” Schaffner 116 (not located).
A
Of the Mexican species, about half are well defined, mostly allopatric with respect to congeners in Mexico, and rather restricted or rare in their distribution. These include nearly all of the exindusiate species (P. mickelii, P. orbiculatum, P. platyphyllum, P. schizophyllum, and P. speciosissimum), as well as the 1-pinnate ones (P. acrostichoides, P. muenchii, P. munitum). The remaining ten species are more difficult to distinguish from each other, and very likely they have incompletely diverged or have come into contact again after being allopatric previously. Mostly these appear to be diploids, but there is evidence that some populations are tetraploid, as judged by the large spores of some herbarium specimens and a few chromosome counts. The central and perhaps most variable species seems to be P. hartwegii, which is also the most widely distributed and common of the Mexican species.
The species of Polystichum appear difficult to define, in part, because of probable hybridization. In tropical regions, this is not very well documented, except for the studies of Barrington (1985a, 1985b), but in temperate regions, hybridization is well studied in northwestern North America, Europe, and Japan. Extensive work needs to be done on the morphological diversity and ecology of individual populations for a better understanding of the species and their dynamics in tropical America. It is also not likely that a fuller understanding of the systematics can be achieved until modern cytotaxonomic and isozymic studies have been done. Additional species may well be recognized once proper studies can be made, and we allude to some interesting unnamed collections at the end of this treatment; it would, however, be premature to describe them now because of the general taxonomic confusion in the genus and also the paucity of collections.
The genus Rumohra, sometimes considered to be related to Polystichum and similar in its peltate indusia, is known to us from a single Mexican collection of Rumohra adiantiformis (G. Forst) Ching: Jalisco, Los Guayabos, “alterado, en una huerta, lugar húmedo,” 1500 m, Pilar Mones U. 18218 (UC). It is nuclear from the label whether this species, often cultivated around the world, has become established and is reproducing on its own or not. It is generally considered to be a circumaustral, polymorphic species, and is also considered native to much of South America (e.g., Venezuela, Peru, Brazil, Bolivia, Chile, Argentina), S. Africa, Madagascar, Australia, and New Zealand. It is also apparently indigenous to the Greater Antilles, but is unknown from Mesoamerica. From Polystichum, Rumohra differs in its adaxially flattened (vs. sulcate) costae, long-creeping dorsiventral rhizomes (vs. short-creeping to suberect, radial), and apically rounded to acute (vs. aristate) ultimate segments.
Hybrids and Problematic Specimens
Here we list and discuss a number of problematic specimens, both those that are putative hybrids (parentage uncertain) andthose that cannot be placed satisfactorily in any species recognized in this treatment at this time.
Breedlove 22605 (DS, MEXU), Chis. Smith (1981) identified this as P. fournieri, with a query. It is not that, but probably a hybrid of uncertain parentage, perhaps involving P. distans. The spores are malformed and very irregular in size and shape.
Mickel 4674 (NY, UC), Oax. This was originally cited as P. hartwegii by Mickel and Beitel (1988), but Barrington annotated it in 1993 as Polystichums P. nov. , aff. P. fournieri. We agree that it is not P. hartwegii and cannot match it with any known species. It differs from P. fournieri in having smaller indusia; perhaps its closest affinity is with P. turrialbae.
Mickel 5310 (NY, UC), Oax. This is peculiar in the exindusiate sori and very reduced proximal pinnae, lowermost ca. 5 pairs gradually shortened, the most basal ones ca. 1 cm long; fronds ca. 45 cm long; blades ca. 35 X 15 cm; larger pinnules pinnatifid, ca. 10 X 5 mm; stipe base scales lanceate, to ca. 8 X 1.5 mm, brownish, entire, not particularly distinctive. We suspect that this specimen represents an undescribed species but are uncertain as to its affinities. Mickel and Beitel (1988) cited it as P. ordinatum, no doubt because of the reduced proximal pinnae, but it does not appear very closely related to that.
Mohr s.n., 1857 (US), Ver. Although the blade is incomplete, this appears to have several pairs of reduced proximal pinnae. It might be P. ordinatum, but the indusia are very large, to 1.8 mm diam. The pinnules are relatively undivided, and so approach those of P. rachichlaena, but we do not otherwise know that species from Edo. Veracruz.
Pringle 5588 (MEXU, US), Ver. This appears to match Mohr s.n., discussed above, with very large indusia and reduced proximal pinnae.
Tenorio 18554 (MEXU–3 sheets), Oax. Most likely this represents an undescribed species, probably confined to high elevations (2800 m). The stipe base scales are most similar to those of P. alfaroi, but concolorous and light orange-brown without a darkened middle band. Pinnules are ± entire and spreading (thus differing from P. alfaroi), with a deltate basal auricle, and coriaceous with revolute margins, similar to some specimens of P. distans (which has completely different stipe base scales). We are unable to suggest its nearest ally.
Unplaced Names
Polystichum aculeatum (L.) Roth α incisum Fée, Mém. Foug. 8: 100. 1857. Type. Mexico. “Cordoba des Mexicains,” Schaffner 250 (not located).
Polystichum aculeatum (L.) Roth ß gracile Fée, Mém. Foug. 8: 100. 1857. Type. Mexico. “Guatimalpan et San Agustin,” Schaffner 315 (not located).
Polystichum aculeatum (L.) Roth γ distans Fée, Mém. Foug. 8: 100. 1857. Type. Mexico, “Totutla des Mexicains,” Schaffner 116 (not located).
A
Bibliografía
C. SEMARNAT 2019: MODIFICACIÓN del Anexo Normativo III, Lista de especies en riesgo de la Norma Oficial Mexicana NOM-059-SEMARNAT-2010: 101 pp. – https://www.dof.gob.mx/nota_detalle.php?codigo=5578808&fecha=14/11/2019#gsc.tab=0 [accessed 2023-05-04 06:16]