Azolla microphylla Kaulf.
Descripción
Plants flattened, ± dichotomously branched, 0.5–2 cm diam.; upper leaf-lobes imbricate, rhombic-ovate to suborbicular, ca. 0.5–0.7 mm long, broadly rounded to obtuse at apices, papillose on upper surfaces, lower lobe larger than upper, the margins purplish-tinged or hyaline; largest papillae on upper leaf lobes 2–3-celled; microsporocarps globose, ca. 1 mm diam.; glochidia of massulae 0–6-septate; megasporocarps 0.25–0.3 mm long; megaspores pitted on basal portion.A
Forma de vida
Hidrófita libreA
Ejemplar revisado
Ags (Rzedowski & McVaugh 734, ENCB). BCN (Thorne 57742, UC, f). Chis (Breedlove 38372, 34927, DS). DF (Rzedowski 21992, ENCB, NY). Gro (Fonseca 1375, 1441, 1590, FCME). Gto (Rzedowski 47246, IEB, UC). Hgo (Rzedowski 32098, IEB). Jal (Mexia 1857, NY, UC). Méx (Rzedowski 31984, 33730, ENCB). Mich (Díaz B. 6388, 6467, IEB, UC). Mor (Bonilla 64, UAMIZ). Nay (Jones 23461, NY, UC). Oax (Camp 2764, ENCB, NY, UC). Pue (Arsène 1208, 2363, US, both f). Sin (Alava 1421, UC, f). SLP (Schaffner s.n., “in 1876 et 81,” NY, US). Tab (Lot & Novelo 1099, MEXU). Ver (Gutiérrez B. 1222, IEB, NY, XAL).
Unverified, Doubtful, or Mistaken Reports. Chih (Knobloch 370, MSC, cited by Knobloch & Correll, 1962, but not verified). Tlax (Zimmerman et al., 1993, but not verified).
A
Unverified, Doubtful, or Mistaken Reports. Chih (Knobloch 370, MSC, cited by Knobloch & Correll, 1962, but not verified). Tlax (Zimmerman et al., 1993, but not verified).
A
Elevación
(0–)1400–2950 mA
Ecología y Hábitat
Floating in water, marshes, stagnant streams.A
Categoría IUCN
Preocupación menor (LC)C
Categoría NOM-059-SEMARNAT-2010
No incluidaD
Discusión taxonómica
There is disagreement over the typification of A. microphylla. Svenson (1944) applied the name primarily to material from South America, but the type was said by Kaulfuss to have been collected in California. Most authors have followed Svenson in excluding California from the range, implying that they thought the provenance of the type was incorrect; however, there is no firm evidence to support this contention, and at least two recent authors have stated otherwise (Tryon & Stolze, 1994; Moran in Davidse et al., 1995). Even Svenson himself stated that “if the Chamisso specimen, which was fruiting, is ever examined, I suspect it will turn out to be either A. mexicana or A. filiculoides.” Most specimens of Azolla from California appear to be the same as Mexican material, and so we apply the older of the two names.
Since Svenson’s (1944) revision of the group, A. mexicana has usually been distinguished from A. microphylla by the branching pattern of the plants (said to be dichotomous in A. mexicana, pinnate in A. microphylla) and megaspore ornamentation (pitted in A. mexicana, smooth in A. microphylla). Other stated differences are not clearcut or the character states are strongly overlapping. Zimmerman et al. (1993) reported A. microphylla to be genetically similar to A. mexicana (as A. caroliniana). Reid (2002) used cladistic analysis of DNA sequence data from three noncoding regions (ITS, atpB-rbcL IGS, and trnL-trnF region) to reconstruct phylogenetic relationships among species of Azolla. She interpreted her results to indicate that the species of sect. Azolla form a monophyletic group. However, A. microphylla and A. mexicana formed a single evolutionary lineage, and multiple accessions sampled from these putative species were interdigitated within the clade. She suggested that this lineage arose through hybridization and homoploid speciation involving A. caroliniana and A. filiculoides, an intriguing hypothesis that needs further testing. For this reason, we choose to treat A. mexicana and A. microphylla as conspecific.
Azolla filiculoides Lam. differs from A. microphylla in having more elongate, pinnately branched stems and generally larger leaves with broader, whitish margins. Most specimens previously identified as A. filiculoides from Mexico are probably A. microphylla, as judged by their dichotomous branching pattern and small, narrowly marginate or emarginate leaves.
Specimens of A. microphylla in Mexico and elsewhere have sometimes been identified as A. caroliniana Willd., but Jermy (in Derrick et al., 1987) reported that the type of that name was shown by Dunham (1986) to be a synonym of A. filiculoides Lam. Svenson (1944) applied the name A. caroliniana in a strict sense, restricting it to specimens from the eastern United States and perhaps the Greater Antilles. Azolla mexicana is regarded by some as only a minor variant of A. caroliniana sensu Svenson (non Willd.) (as, for example by Zimmerman et al., 1993). The same species is also naturalized in the OldWorld, e.g., in Europe (Pieterse et al., 1977, as A. caroliniana).
A
Since Svenson’s (1944) revision of the group, A. mexicana has usually been distinguished from A. microphylla by the branching pattern of the plants (said to be dichotomous in A. mexicana, pinnate in A. microphylla) and megaspore ornamentation (pitted in A. mexicana, smooth in A. microphylla). Other stated differences are not clearcut or the character states are strongly overlapping. Zimmerman et al. (1993) reported A. microphylla to be genetically similar to A. mexicana (as A. caroliniana). Reid (2002) used cladistic analysis of DNA sequence data from three noncoding regions (ITS, atpB-rbcL IGS, and trnL-trnF region) to reconstruct phylogenetic relationships among species of Azolla. She interpreted her results to indicate that the species of sect. Azolla form a monophyletic group. However, A. microphylla and A. mexicana formed a single evolutionary lineage, and multiple accessions sampled from these putative species were interdigitated within the clade. She suggested that this lineage arose through hybridization and homoploid speciation involving A. caroliniana and A. filiculoides, an intriguing hypothesis that needs further testing. For this reason, we choose to treat A. mexicana and A. microphylla as conspecific.
Azolla filiculoides Lam. differs from A. microphylla in having more elongate, pinnately branched stems and generally larger leaves with broader, whitish margins. Most specimens previously identified as A. filiculoides from Mexico are probably A. microphylla, as judged by their dichotomous branching pattern and small, narrowly marginate or emarginate leaves.
Specimens of A. microphylla in Mexico and elsewhere have sometimes been identified as A. caroliniana Willd., but Jermy (in Derrick et al., 1987) reported that the type of that name was shown by Dunham (1986) to be a synonym of A. filiculoides Lam. Svenson (1944) applied the name A. caroliniana in a strict sense, restricting it to specimens from the eastern United States and perhaps the Greater Antilles. Azolla mexicana is regarded by some as only a minor variant of A. caroliniana sensu Svenson (non Willd.) (as, for example by Zimmerman et al., 1993). The same species is also naturalized in the OldWorld, e.g., in Europe (Pieterse et al., 1977, as A. caroliniana).
A