Monographs Details:
Authority:
Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
Family:
Blechnaceae
Blechnaceae
Description:
Species Description - Rhizome erect, stoloniferous; rhizome scales 4-7 mm long, 0.8-1 mm wide, bicolorous, central portion dark brown, outer margin pale brown, lanceolate, margin minutely serrulate or ciliate near apex; fronds clumped; stipe 17-28 cm, ca. ½ the frond length, stramineous, papillate, glabrous with scattered scales at base; blade 17-28 cm long, (8.5-) 11-17(-22) cm wide, pinnate, lanceolate to ovate-lanceolate, slightly or not at all reduced at base, pinnae distant in basal 2/3 of frond, apex gradually pinnatifid; rachis stramineous, grooved, papillate, glabrous; largest pinnae (4.5-)6-9(-12.5) cm long, 7-18 mm wide, linear-lanceolate, subfalcate, subcordate to cordate and petiolate in basal pinnae, abaxially glabrous, adaxially glabrous with grooved midvein; veins once-forked, enlarged vein endings visible adaxially; pinna margin minutely toothed, with intramarginal row of serrulations; indusia most of length of pinna, 0.8 mm, entire to minutely erose-ciliate.
Species Description - Rhizome erect, stoloniferous; rhizome scales 4-7 mm long, 0.8-1 mm wide, bicolorous, central portion dark brown, outer margin pale brown, lanceolate, margin minutely serrulate or ciliate near apex; fronds clumped; stipe 17-28 cm, ca. ½ the frond length, stramineous, papillate, glabrous with scattered scales at base; blade 17-28 cm long, (8.5-) 11-17(-22) cm wide, pinnate, lanceolate to ovate-lanceolate, slightly or not at all reduced at base, pinnae distant in basal 2/3 of frond, apex gradually pinnatifid; rachis stramineous, grooved, papillate, glabrous; largest pinnae (4.5-)6-9(-12.5) cm long, 7-18 mm wide, linear-lanceolate, subfalcate, subcordate to cordate and petiolate in basal pinnae, abaxially glabrous, adaxially glabrous with grooved midvein; veins once-forked, enlarged vein endings visible adaxially; pinna margin minutely toothed, with intramarginal row of serrulations; indusia most of length of pinna, 0.8 mm, entire to minutely erose-ciliate.
Discussion:
Type. Uncertain; LINN 1247.1 is this species but, according to Jackson (1912), was added to LINN after 1755. Petiver and Morrison illustrations are also cited. The Blechnum occidentale complex, in Oaxaca comprising B. occidentale s.s., B. glandulosum, B. polypodioides and B. gracile, is a difficult group to deal with in the neotropics, both systematically and nomenclaturally. Walker (1966, 1973, 1985) has shown in Jamaica and Trinidad that numerous sterile hybrids exist but “. . . unlike the situation in most other genera, sterile interspecific hybrids are not always easy to detect on herbarium material using the presence of abortive spores as a criterion. The spores in this complex seem to be more or less colorless and the abortive ones do not seem to collapse to the extent found in many other fern hybrids.” Many authors (e.g., Murillo, 1968; Stolze, 1981) interpret these species more broadly as being extremely variable, failing to recognize the occurrence of hybrids. In light of the excellent work of Walker in Jamaica and Trinidad, a narrower species view seems more useful. However, acceptance of hybridization exposes only the tip of the iceberg, since the far more complicated problem of sorting out the possible primary hybrids, allopolyploids and backcross hybrids then arises. By recognizing B. glandulosum and B. occidentale as separate species and presenting some new interpretations in the B. gracile-fraxineum group, part of the problem should be clarified, and hypotheses for further testing provided. The numerous names and types make for difficulties in assigning the oldest name to the taxonomic entities, and some changes are to be expected. In Oaxaca the glabrous Blechnum occidentale s.s. occurs at 50-900 m elevation whereas the pubescent B. glandulosum occurs at 900-2150 m, which is also the case in Guatemala (A. R. Smith, 1981: 60; Stolze, 1981: 111, as B. occidentale var. occidentale and var. pubirhachis). The differences in size (as enumerated in our key and descriptions) appear consistent with the elevation and pubescence, not only in Oaxaca, but throughout most of Mexico. Blechnum glandulosum is more common in the central, higher portion of Oaxaca and also farther north. Its occurrence decreases in elevation until it is the “B. occidentale” found at low elevation in Florida. Both Blechnum occidentale and B. glandulosum are characterized by fully pinnate basal pinnae, distant pinnae in at least the basal half of the blade, almost no or only slight reduction in the basal pinnae and strictly pinnatifid apices. Hybrids with B. gracile can be detected by the smaller number of pinnae and the semi-conform apical portion, whereas hybrids with B. polypodioides have basal pinnae reduced and half ad-nate (acroscopic portion of basal pinna adnate but the basiscopic portion is cordate), falcate pinnae that are adnate over the apical 2/3 of the blade and a narrow, linear blade. These hybrids are further discussed and their occurrence noted under the discussions of B. gracile and B. polypodioides. Several collections are suspected (on the basis of abortive spores and intermediate characters) of representing the expected hybrid combination B. glandulosum x occidentale. They are intermediate to small in size, only sparsely hairy and occur at generally higher elevation than does B. occidentale. The specimens (all NY) are from Teotitlán (4103, 2150-2250 m), Pochutla (5059, 1400 m; 5023, 2200 m), Juquila (6127, 750 m) and Villa Alta (1020a, 1150 m) in Oaxaca, as well as Chiapas (Gittins 4206, 1600 m; Breedlove 29103, 1350 m). Two abortive-spored specimens, one from Chiapas (Ghiesbreght 277) and one from Guerrero (Hinton 14049), are unusual in being wide (22-24 cm) but having densely hairy rachises. Blechnum falciculatum Presl (Epi-mel. bot. 106. 1849 [1851]. Type. Mexico. Veracruz, Galeotti 6397 (BR!-2 sheets, photos BM, GH, US!; isotype K) appears to be this latter form of the hybrid.
Type. Uncertain; LINN 1247.1 is this species but, according to Jackson (1912), was added to LINN after 1755. Petiver and Morrison illustrations are also cited. The Blechnum occidentale complex, in Oaxaca comprising B. occidentale s.s., B. glandulosum, B. polypodioides and B. gracile, is a difficult group to deal with in the neotropics, both systematically and nomenclaturally. Walker (1966, 1973, 1985) has shown in Jamaica and Trinidad that numerous sterile hybrids exist but “. . . unlike the situation in most other genera, sterile interspecific hybrids are not always easy to detect on herbarium material using the presence of abortive spores as a criterion. The spores in this complex seem to be more or less colorless and the abortive ones do not seem to collapse to the extent found in many other fern hybrids.” Many authors (e.g., Murillo, 1968; Stolze, 1981) interpret these species more broadly as being extremely variable, failing to recognize the occurrence of hybrids. In light of the excellent work of Walker in Jamaica and Trinidad, a narrower species view seems more useful. However, acceptance of hybridization exposes only the tip of the iceberg, since the far more complicated problem of sorting out the possible primary hybrids, allopolyploids and backcross hybrids then arises. By recognizing B. glandulosum and B. occidentale as separate species and presenting some new interpretations in the B. gracile-fraxineum group, part of the problem should be clarified, and hypotheses for further testing provided. The numerous names and types make for difficulties in assigning the oldest name to the taxonomic entities, and some changes are to be expected. In Oaxaca the glabrous Blechnum occidentale s.s. occurs at 50-900 m elevation whereas the pubescent B. glandulosum occurs at 900-2150 m, which is also the case in Guatemala (A. R. Smith, 1981: 60; Stolze, 1981: 111, as B. occidentale var. occidentale and var. pubirhachis). The differences in size (as enumerated in our key and descriptions) appear consistent with the elevation and pubescence, not only in Oaxaca, but throughout most of Mexico. Blechnum glandulosum is more common in the central, higher portion of Oaxaca and also farther north. Its occurrence decreases in elevation until it is the “B. occidentale” found at low elevation in Florida. Both Blechnum occidentale and B. glandulosum are characterized by fully pinnate basal pinnae, distant pinnae in at least the basal half of the blade, almost no or only slight reduction in the basal pinnae and strictly pinnatifid apices. Hybrids with B. gracile can be detected by the smaller number of pinnae and the semi-conform apical portion, whereas hybrids with B. polypodioides have basal pinnae reduced and half ad-nate (acroscopic portion of basal pinna adnate but the basiscopic portion is cordate), falcate pinnae that are adnate over the apical 2/3 of the blade and a narrow, linear blade. These hybrids are further discussed and their occurrence noted under the discussions of B. gracile and B. polypodioides. Several collections are suspected (on the basis of abortive spores and intermediate characters) of representing the expected hybrid combination B. glandulosum x occidentale. They are intermediate to small in size, only sparsely hairy and occur at generally higher elevation than does B. occidentale. The specimens (all NY) are from Teotitlán (4103, 2150-2250 m), Pochutla (5059, 1400 m; 5023, 2200 m), Juquila (6127, 750 m) and Villa Alta (1020a, 1150 m) in Oaxaca, as well as Chiapas (Gittins 4206, 1600 m; Breedlove 29103, 1350 m). Two abortive-spored specimens, one from Chiapas (Ghiesbreght 277) and one from Guerrero (Hinton 14049), are unusual in being wide (22-24 cm) but having densely hairy rachises. Blechnum falciculatum Presl (Epi-mel. bot. 106. 1849 [1851]. Type. Mexico. Veracruz, Galeotti 6397 (BR!-2 sheets, photos BM, GH, US!; isotype K) appears to be this latter form of the hybrid.
Distribution:
Mexico North America| Argentina South America| Brazil South America| Venezuela South America| Colombia South America| Trinidad and Tobago South America| Panama Central America| Guatemala Central America|
Mexico North America| Argentina South America| Brazil South America| Venezuela South America| Colombia South America| Trinidad and Tobago South America| Panama Central America| Guatemala Central America|