Blechnum gracile Kaulf.
Descripción
Rhizomes erect, short-creeping to ascending, stoloniferous; rhizome scales concolorous, brown to dark brown, narrowly lanceolate, 2–5 X 0.5–0.8 mm, margins with rare teeth; fronds monomorphic, the fertile often somewhat longer and more erect than sterile, clumped; stipes 1.8–22 cm X 1–2 mm, 1⁄3–2⁄3 the frond length, stramineous, smooth to obscurely papillate, with sparse scales orange or orange-brown scales at bases, these to 6 X 1.5 mm; blades 8–25 X 3–12 cm, 1-pinnate; rachises stramineous, glabrous, lacking aerophores at pinna bases; pinnae 2–4(–8) pairs, distant, proximal pinnae slightly reduced, apices conform, 1.5–3 times length of lateral pinnae, bases of terminal pinna often with 0–2 semicircular confluent to separate lobes (4–6 mm long), largest lateral pinnae 2–8 X 0.8–1.5 cm, bases rounded to broadly cuneate, terminal pinna 6–15 cm X 10–20 mm, pinna margins entire or nearly so, sometimes incurved, glabrous on both sides, costae grooved adaxially; veins simple to 1(–2)-forked, enlarged vein endings visible on adaxial surfaces; indusia tan, 0.3–0.5 mm wide, entire or subentire.A
Forma de vida
TerrestreA
Ejemplar revisado
Chis (Breedlove 31587, DS, MEXU, NY; Purpus 6738, NY, US). Gro (Hinton 11039, NY; Lorea 2416, IEB, MEXU, UC). Jal (McVaugh 26402, IEB, MEXU, MICH, NY). Nay (Téllez 12849, MEXU). Oax (Mickel 6085, NY, UC, US, 7381a, MEXU, NY). Tab (Becerra s.n., 8 Apr 1914, MEXU). Ver (Purpus 2376, BM, MO, NY, UC; Ventura A. 12501, IEB, MEXU).
Unverified, Doubtful, or Mistaken Reports. Qro (Fernández 4208, ENCB, cited by Arreguín et al., 2001, but not verified).
A
Unverified, Doubtful, or Mistaken Reports. Qro (Fernández 4208, ENCB, cited by Arreguín et al., 2001, but not verified).
A
Elevación
20 – 920(– 1150) mA
Ecología y Hábitat
On banks and along streams in wet forests of low to middle elevation.A
Tipo de vegetación
Bosque de encino, Selva alta, Selva bajaA
Categoría IUCN
No incluidaB
Categoría NOM-059-SEMARNAT-2010
No incluidaC
Discusión taxonómica
Among the monomorphic taxa, B. gracile is characterized by 1–3(–4) lateral pinna pairs, conform terminal pinnae 1.5–3 times the length of the lateral pinnae, blade apices often with subcordate bases and/or 1–2 semicircular lobes below the terminal pinna, glabrous rachises, and distant, glabrous pinnae with cuneate or rounded bases.
Morphologically, B. gracile matches the tetraploid B. fraxineum sensu Walker (1966, 1973, 1985), who analyzed this entity cytologically from Trinidad. The name B. fraxineum Willd. has often been used for specimens of B. gracile in Mexico and elsewhere in the range, but in the strict sense the name B. fraxineum is believed to apply to sterile triploids between B. meridense Klotzsch (syns: B. longifolium Willd., non Cav.; B. schlimense Fée), a diploid taxon, and B. gracile (Mickel & Beitel, 1988). Blechnum meridense differs from B. gracile in having fertile and sterile fronds similar in size and shape (vs. narrower, longer fertile fronds in B. gracile), terminal pinna similar in size and shape to lateral pinnae (vs. much shorter and often rounded lateral pinnae in B. gracile), and terminal pinna cuneate proximally (vs. subcordate, with rounded lobes in B. gracile).
Blechnum gracile evidently hybridizes with several other species in the complex. Some of these putative hybrids, as judged by their intermediate morphology between the suspected parents, are discussed below; see also under B. appendiculatum for discussion of hybrids with that species.
Blechnum gracile X occidentale (= B. X caudatum): Chis (Breedlove 34096, DS; Martínez S. 8273, 8300, 8349, MEXU; Matuda 3612, LL, MEXU; Purpus 6738, UC). Gro (Langlassé 934, US). Oax (Cruden 1115, MEXU, UC; Hernández G. 1986, CAS, CHAPA, MEXU, MO; Mexia 9181, CAS, LL, MO, NY, UC, 9181b, NY, UC; Mickel 6086b, NY, 6867b, 7381b, NY, UC). Pue (López-Forment Conradt 119, MEXU). Ver (Calzada 918, CAS, MEXU; Ventura A. 15691, MEXU, 18933, ENCB, MEXU, XAL).
Range (partially reported by Mickel & Beitel, 1988): s Mexico, Guat., Bel, Hond, CR; Cuba; Ven, Trin. In Mexico, this hybrid grows at low elevations (150–500 m) along both the Atlantic and Pacific slopes. It occurs in mixed collections with B. gracile (Mickel 7381b, 6086b), and with B. occidentale s.str. (Mexia 9181b, NY, UC; Mickel 6867b). Normal spore production has not been seen in any of the specimens cited, and in many of the putative hybrids the sporangia seem collapsed (e.g., Cruden 1115, UC; Mexia 9181, UC); Calzada 918 has the spores strongly malformed and collapsed. Hybrids between B. gracile and B. occidentale have fertile fronds narrower than the sterile. The name B. caudatum Cav., pro sp., Descr. Pl. 262, 1801, lectotype (designated by Christensen, 1937) from Ecuador, Née s.n. (MA) (see discussion by Moran in Davidse et al., 1995: 326) apparently applies to this hybrid. See discussion under B.meridense for another hybrid, B. antillanum, of similar blade dissection but abaxially hairy along the rachises.A
Morphologically, B. gracile matches the tetraploid B. fraxineum sensu Walker (1966, 1973, 1985), who analyzed this entity cytologically from Trinidad. The name B. fraxineum Willd. has often been used for specimens of B. gracile in Mexico and elsewhere in the range, but in the strict sense the name B. fraxineum is believed to apply to sterile triploids between B. meridense Klotzsch (syns: B. longifolium Willd., non Cav.; B. schlimense Fée), a diploid taxon, and B. gracile (Mickel & Beitel, 1988). Blechnum meridense differs from B. gracile in having fertile and sterile fronds similar in size and shape (vs. narrower, longer fertile fronds in B. gracile), terminal pinna similar in size and shape to lateral pinnae (vs. much shorter and often rounded lateral pinnae in B. gracile), and terminal pinna cuneate proximally (vs. subcordate, with rounded lobes in B. gracile).
Blechnum gracile evidently hybridizes with several other species in the complex. Some of these putative hybrids, as judged by their intermediate morphology between the suspected parents, are discussed below; see also under B. appendiculatum for discussion of hybrids with that species.
Blechnum gracile X occidentale (= B. X caudatum): Chis (Breedlove 34096, DS; Martínez S. 8273, 8300, 8349, MEXU; Matuda 3612, LL, MEXU; Purpus 6738, UC). Gro (Langlassé 934, US). Oax (Cruden 1115, MEXU, UC; Hernández G. 1986, CAS, CHAPA, MEXU, MO; Mexia 9181, CAS, LL, MO, NY, UC, 9181b, NY, UC; Mickel 6086b, NY, 6867b, 7381b, NY, UC). Pue (López-Forment Conradt 119, MEXU). Ver (Calzada 918, CAS, MEXU; Ventura A. 15691, MEXU, 18933, ENCB, MEXU, XAL).
Range (partially reported by Mickel & Beitel, 1988): s Mexico, Guat., Bel, Hond, CR; Cuba; Ven, Trin. In Mexico, this hybrid grows at low elevations (150–500 m) along both the Atlantic and Pacific slopes. It occurs in mixed collections with B. gracile (Mickel 7381b, 6086b), and with B. occidentale s.str. (Mexia 9181b, NY, UC; Mickel 6867b). Normal spore production has not been seen in any of the specimens cited, and in many of the putative hybrids the sporangia seem collapsed (e.g., Cruden 1115, UC; Mexia 9181, UC); Calzada 918 has the spores strongly malformed and collapsed. Hybrids between B. gracile and B. occidentale have fertile fronds narrower than the sterile. The name B. caudatum Cav., pro sp., Descr. Pl. 262, 1801, lectotype (designated by Christensen, 1937) from Ecuador, Née s.n. (MA) (see discussion by Moran in Davidse et al., 1995: 326) apparently applies to this hybrid. See discussion under B.meridense for another hybrid, B. antillanum, of similar blade dissection but abaxially hairy along the rachises.A