Polypodiaceous Ferns Research Articles

Comparative rhizome anatomy of polypodiaceous ferns from eastern Himalaya and its taxonomic implications

Polypodiaceae is the second largest family of ferns characterized by creeping rhizomes covered with scales whose systematics however is mainly focused on frond and reproductive structures. Over the years, studies have demonstrated the significance of rhizome anatomical characters for fern taxonomy. However, work focusing on rhizome anatomy from the eastern Himalayan species is scanty. Morpho-anatomical characters of rhizome and rhizome scales of 30 fern species have been evaluated and compared for its taxonomic significance. Detailed observations were made using a light microscope (LM). Comparative micro-morphological and anatomical traits shared by close phylogenetically related species are also discussed. Anatomical traits like the presence and position of sclerenchymatic tissues, sclereids, thick lignified circumendodermal (CB) bands of vascular bundles, rhizome scales are taxonomically relevant. Characters of rhizome scale delimit several genera and are diagnostic for Polypodiaceae. The comparative rhizome anatomy helps us to better understand this fern family and the scale features outlined will aid in easy identification of several species. An artificial dichotomous key is constructed to discern the morpho-anatomical characters in the segregation of the examined species.

Implications of stipe and midrib morpho-anatomy on the taxonomy of Polypodiaceous ferns

After decades of uncertainty, the current fern classification corroborates traditional morphology with molecular evidence and is widely accepted. However, in the complex family Polypodiaceae, some major generic recircumscriptions are still open. The present study aims to provide a comprehensive account of the stipe and midrib morpho-anatomical features of polypodiaceous ferns from the eastern Himalayan region. Fresh specimens belonging to 24 species were collected from the study area. Macro-morphological features like colour, size, and texture were observed in the field with the aid of a dissection microscope while micro-morphological traits like scales, indument, and anatomical details were observed under a compound microscope. The type of tissues, arrangement of vascular bundles, the shape of xylem, and circumendodermal band seem to be of taxonomic significance. The UPGMA reveals comparable correlations with previously published clades and relationships based on morphological as well as molecular data.

Micro-morphological characters in Polypodiaceae and its taxonomic significance

The present study insights into the interrelationships and taxonomic segregation of some Polypodiaceous fern taxa based on leaf architecture and foliar micro-morphology. Twenty-seven fern species were examined and valuable qualitative and quantitative data were obtained to generate UPGMA dendrogram. A dichotomous key differentiating the taxa was prepared. Results reveal that even though species have overlapping characters, certain specific traits prove taxonomically valuable. The results proved that traits like leaf shape, higher order leaf venation, stomatal and epidermal features are indeed important diagnostic characters and hence can be used for the identification of fern species in their immature stage or even in absence of sori. These data sets often combined with other morphological as well molecular data would contribute to fern phylogenetic study particularly of the large and complex family Polypodiaceae.

The exception seems to be the rule: Nectaries in Serpocaulon and an update of their presence in Polypodiaceae

Although nectaries are widely known among angiosperms, few records exist for ferns, and there are even fewer studies focusing on their anatomy. We noticed nectaries in Serpocaulon (Polypodiaceae) and confirmed their presence in six taxa of the genus. We conducted a structural analysis using light and scanning electron microscopy and revised occurrence records of nectaries in polypodiaceous ferns. Nectar secretion was observed in young fronds and was restricted to the basal pinnae/segments. We did not detect any differentiated glandular tissue in the portions where the nectar was released, which implies that the nectar secreting glands in the studied taxa should be regarded as non-structural nectaries. Nonetheless, we found the mesophyll in these portions to usually be compact (i. e. with inconspicuous and relatively fewer intercellular spaces), sometimes with cells with distinct dense protoplast. In addition, prominent stomata with elevated guard cells were observed in nectary portions, probably constituting pathways through which nectar exudates. An update record for nectaries in Polypodiaceae was presented; these structures were recorded in 8% of Serpocaulon and ca. 1% of the species of the family, most being epiphytic with pinnatisect laminae dissection. While extrafloral nectaries are mostly related to protection against herbivores, nectary ecology in ferns is poorly understood, and a protective role of these structures cannot be discarded. However, further investigation is needed and encouraged to develop a comprehensive understanding of fern nectaries in light of their evolutionary history and ecological roles.

The complete chloroplast genome sequence of Polypodiodes amoena (Polypodiaceae), an important medical fern

Polypodiodes amoena is an important medical fern of Polypodiaceae. Its complete chloroplast genome is obtained through Illumina sequencing, which is 152,067 bp in length with a large single copy (LSC) region (81,187 bp), a small single copy (SSC) region (21,590 bp), and two inverted repeats (IRa and IRb) regions (24,645 bp). The genome encodes 130 genes, including 88 protein-coding genes, 33 tRNA genes, eight rRNA genes, and one pseudogene. ML phylogenetic analysis reveals that P. amoena is clustered with polypodiaceous ferns.

Characterization of the complete chloroplast genome of Leptochilus decurrens (Polypodiaceae), a least concern folk medicinal fern

Leptochilus decurrens is a small tropical fern of Polypodiaceae, but also a least concern folk medicinal fern. Its genome size is 153,753 bp with a pair of 21,664 bp inverted repeat regions (IR), a large single-copy (LSC) region of 84,395 bp and a small single-copy (SSC) region of 26,030 bp. A total of 133 genes were predicted, including 88 protein-coding genes, 37 tRNA genes and eight rRNA genes. The ML analysis reveals that L. decurrens is sister to Leptochilus hemionitideus forming monophyletic group closely related with polypodiaceous ferns. The work provides vigorous molecular data to further promote phylogenetics of Polypodiaceae.

Pteridophytes: evolutionary boon as medicinal plants

Pteridophytes: evolutionary boon as medicinal plants

Polypodiodes simonsiana (Polypodiaceae) – новый папоротник из Северо-Восточной Индии и Мьянмы

Polypodiodes simonsiana Fraser-Jenk. et Shalimov, a new species of polypodiaceous fern from north eastern India and Myanmar, is described and illustrated. It is related to P. amoena (Wall. ex Mett.) Ching and P. niponica (Mett.) Ching, but is characterised by its prominently backward-deflexed, acutely pointed, elongatedtriangular lower and mid pinnae, tapering evenly from their wide bases to their narrow acute apices. Its IUCN conservation status is assessed as VU (Vulnerable).

From the Himalayan region or the Malay Archipelago: Molecular dating to trace the origin of a fern genus Phymatopteris (Polypodiaceae)

Phymatopteris Pic. Serm., a derived polypodiaceous fern, is one of the many fern genera that still suffer from nomenclatural confusion. Its generic circumscription and phylogenetic relationships with other selligueoid ferns have been controversial, and its geographic origin, whether in the Himalayan region of continental Asia or in Malay Archipelago, is still unknown. A phylogeny of all selligueoid ferns based on 4 cpDNA (rbcL, trnL-F, rps4 and rps4-trnS) regions indicates that Phymatopteris is not monophyletic. Phymatopteris species are distributed in 5 well-supported clades that can be distinguished with frond-shape and frond-margin characters. All early-divergent species are from the Malaysian Archipelago, while the remaining species are all from the Himalayan region and form a recently diverged group that is largely unresolved, most likely having resulted from an explosive radiation. Divergence-time estimation suggests that the first diversification of selligueoid ferns occurred at ca. 27 Ma in the Malaysian Archipelago, followed by migration into the Himalayan region around 20 Ma. The radiation of the Himalayan species occurred mostly within the last 20 million years, within the period of recent major uplifts of the Qinghai-Tibetan Plateau (between the early Miocene and the Pleistocene) and late-Cenozoic global cooling. Our evidence leads us to propose that the Malaysian Archipelago is the ancestral area for Phymatopteris.

A new Drynaria (Polypodiaceae) from the Upper Pliocene of Southwest China

A polypodiaceous fern, Drynaria callispora sp. nov., is described from the upper Pliocene Sanying Formation in western Yunnan Province, southwestern China. This species with well-preserved pinnae and in situ spores is the first convincing Drynaria fossil record. Detailed morphological investigation reveals that D. callispora is characterized by 1) pinnatifid fronds with entire-margined pinnae having straight or zigzag secondary veins; 2) finer venation showing void quadrangular areoles, but occasionally with one unbranched veinlet; 3) one row of circular sori on each side of the strong primary vein; and 4) in situ spores with verrucate exospores elliptical in polar view and bean-shaped in equatorial view. A morphological comparison shows that D. callispora is significantly different from all the fossil species previously identified as drynarioids. A phylogenetic analysis of D. callispora supports that the fossil is closely related to D. sinica Diels and D. mollis Bedd., two extant species distributing in the Himalayas. The discovery of the new fern indicates that the genus Drynaria became diversified in its modern distribution region no later than the late Pliocene and had retained a similar ecology to that of many modern drynarioid ferns ever since.

A permineralized species of mangrove fern Acrostichum L. from Deccan Intertrappean beds of India

Acrostichum intertrappeum sp. nov., a permineralized aerial stem with helically arranged petioles and roots in organic connection, is described from the Deccan Intertrappean beds of Nawargaon, District Wardha, Maharashtra, India and forms the first and the oldest record of its kind. The stem is covered with a thick ramentum of large multicellular scales and is characterized by a three angled dictyostele enclosing a few medullary bundles. The petioles are helically arranged and the vascular morphology is distinct with abaxial horseshoe-shaped ring, adaxial linear row and central dorso-ventrally elongated ring. The roots have hexarch steles and aerenchymatous cortex with large air cavities in rings. Occurrence of Acrostichum along with coastal palms, mangroves and marsh plants described earlier from this region and nearby locations suggests the north-western shore of the Deccan was linked to the equatorial ocean (South Western Tethys Sea) probably through the Narmada Valley during the deposition of Intertrappean sediments. Morphological features and anatomical characters of the fossil reveal that Acrostichum grew in marsh swamp environment or on mud flats of back water areas of the coastal environment prevailing a tropical humid climate when the Deccan region was almost at an equatorial position during the Late Cretaceous period. This new record further adds to a growing body of data on the diversification of polypodiaceous ferns that point to a much earlier crown group radiation of the group than previously thought.

Fern spore diversity and abundance in Australia during the Cretaceous

Changes in the Cretaceous fern flora of Australia were analysed by compiling data from the palynological literature. A decline in the relative diversity and abundance of free-sporing plants during the Late Cretaceous was concurrent with a rise in angiosperms, while the relative contribution of gymnosperms was unchanged. Ferns and lycophytes were the major contributors to the free-sporing plant pattern and declined markedly from higher Early Cretaceous levels; bryophyte relative diversity peaks in the mid-Cretaceous. The fern families Schizaeaceae, Osmundaceae and Cyatheaceae/Dicksoniaceae decline only marginally, with most of the decline seen in ‘miscellaneous ferns’ (mostly comprising fern spores of unknown affinity). In contrast to the overall fern trend, the relative diversity of Gleicheniaceae increased significantly in the mid-Cretaceous. The decline in fern relative abundance, which is gradual throughout the entire Cretaceous, is equally complex. By far the largest contributor to this decline is Osmundaceae. Cyathaceae/Dicksoniaceae and Gleicheniaceae increase in relative abundance in the mid-Cretaceous, but decline in the Late Cretaceous. Matoniaceae/Dipteridaceae maintain very low and stable levels of relative diversity and abundance throughout the Cretaceous. There is no evidence that polypodiaceous ferns sensu lato underwent any significant radiation concomitant with the angiosperm radiation in the Late Cretaceous. Trends observed in the relative diversity and abundance show that patterns occurring at high taxonomic levels (e.g. all ferns) are not consistent at lower levels (e.g. families). The Australian and North American diversity data for free-sporing plants, gymnosperms and angiosperms are broadly similar. However, Schizaeaceae and Gleicheniaceae display different trends during the mid-Cretaceous, increasing in diversity in the Australian palynofloras, but decreasing in North America.

An Early Cretaceous root-climbing epiphyte (Lindsaeaceae) and its significance for calibrating the diversification of polypodiaceous ferns

The discovery of fossilised roots of a lindsaeoid fern within the trunk of the extinct tree fern Tempskya provides new fossil evidence for Lindsaeaceae in the Mesozic, as well as the first direct evidence of an ecological association between Tempskya and root-climbing epiphytes. Data were collected from permineralised Tempskya trunks from the Aspen Shale (Early Cretaceous, Albian), Wyoming (USA). The roots of the lindsaeoid fossil are clearly distinguishable from those of Tempskya and other living ferns based on a suite of distinctive anatomical features, which are described in detail. The foliage is unknown. The new fossil is interpreted as a root climber, and comparisons are made with similar living species in Lindsaea subgenus Odontoloma (Lindsaeaceae). The documentation of Lindsaeaceae in the Early Cretaceous adds to a small but growing body of data on the diversification of polypodiaceous ferns during this important period. These recent discoveries point to a much earlier (Early Cretaceous) crown group radiation of polypodiaceous ferns than previously suspected.

Interpopulational Comparison of Dose-Mediated Antheridiogen Response in Onoclea sensibilis

Interpopulational Comparison of Dose-Mediated Antheridiogen Response in Onoclea sensibilis

An Experimental Study on the Effects of Earthworms on the Ecological Success of Fern Gametophytes

The successful establishment and maintenance of pteridophyte populations requires the co-occurrence of both the gametophyte and the sporophyte life history phases. Yet, most studies of pteridophyte ecology consider only the sporophyte stage (eg. Grime, 1985). While there are a few studies of gametophyte ecology (eg., Cousens, 1988; Duckett, 1985), there is little knowledge of the factors that limit the distribution and abundance of gametophytes. One factor relevant to the gametophyte phase is the earthworm. Modern families of earthworms likely radiated in soils characteristic of angiosperm forests (Satchell, 1983; Bouche, 1983; Piearce, 1989). Lovis (1977) suggests that the modern polypodiaceous ferns radiated in response to ecological changes brought about by the radiation of the angiosperms. Modern genera of earthworms and leptosporangiate ferns evolved during the Tertiary in communities dominated by angiosperms (Lovis, 1977; Bouche, 1983). Earthworms are known to be involved in dispersal of both the seeds of spermatophytes (McRill & Sagar, 1973) and the spores of pteridophytes (Hamilton, 1988). Earthworms may play a particularly important role in bringing buried seeds and spores to the surface and placing them in improved sites for germination (Grant, 1983). Earthworms naturally till the soil, providing increased aeration, increased porosity and a more even distribution of soil nutrients. They also positively influence soil nutrient content by acting as a first step in the decomposition of detritus, and cause an increase in the numbers and diversity among microbial populations in the soil, thereby increasing the rate of decomposition, and increasing nutrient turnover rates (Lee, 1985). Earthworms prey on small pieces of vegetation, fungi, algae, and even other earthworms (Darwin, 1881; Lavelle, 1983; Lee, 1985). The green, surface dwelling gametophytes characteristic of modern ferns would likely make excellent prey for earthworms. As earthworms have been shown to be influential in the gametophyte habitat, an experiment was undertaken to determine if the presence of earthworms influences the germination of spores, gametophyte establishment, and/or gametophyte reproductive success.

Ecological and phytogeographical observations on the fern flora of Pithoragarh district (north-west Himalaya)

A detailed account of ecology and phytogeography of the ferns of Pithoragarh district of Kumaon (north-west Himalaya) is discussed. Common mesophytic ferns are the species ofAdiantum, Athyrium, Cheilanthes, Christella, Dryopteris, Lygodium, Osmunda, Pseudocyclosorus andPteris. Polypodiaceous ferns are either epiphytes or lithophytes.Ceratopteris thallictroides is the only aquatic fern. From phytogeographical point of view it is observed that on the one hand the fern flora of this region bridges the floristics of eastern and western Himalaya, and on the other it resembles much with the fern flora of south China. About 70% ferns are common with Simla hills and 85% with Darjeeling and Sikkim himalaya.

EVIDENCE FOR POST‐TRANSLATIONAL MODIFICATION OF TRIOSE PHOSPHATE ISOMERASE (TPI) IN ISOËTES (ISOËTACEAE)

As part of an electrophoretic study on Isoites, a number of Neotropical and North American species were examined for allozyme variation in TPI. Three of these species-L storkii, L flaccida, and L mexicana-exhibit three distinct zones of TPI activity. The two most anodally migrating zones are comparable to the two zones found in most angiosperms and in several other species of Isoetes. The single or three-banded phenotypes produced at these loci correspond, respectively, to the homozygous and heterozygous pattems typical of a dimeric enzyme. The most cathodal zone (zone III) differs in producing either single or two-banded phenotypes. Analyses of these three zones indicate a nearly perfect correlation between zones II and III in putative allelic constitution and relative allelic mobility. Explanations involving TPI gene duplications and/or null alleles fail to account for the peculiar banding characteristics and origin of activity zone III. An altemative hypothesis involving a protease duplication and differential post-translational modification is postulated. This hypothesis adequately explains the zone III phenotypes and fixation of the third activity zone in the species examined. Amino acid sequencing is suggested as the most direct test of this hypothesis. The taxonomic distribution of TPI III generally supports a previous, morphologically-based, hypothesis on species relationships in Isoetes. The presence of this zone is regarded as an independent synapomorphy for a major clade of Neotropical Isoetes. TRIOSE PHOSPHATE ISOMERASE (TPI) is a glycolytic enzyme mediating the interconversion of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate. A majority of diploid angiosperms and certain pteridophytes typically exhibit two zones of banding activity on starch gels indicating that TPI is encoded by two loci. Genetic studies (Gottlieb, 1982) have shown that these two zones do in fact represent discrete loci, both of which are nuclear. Additional studies employing pollen exudates and cell fractionations (Gottlieb, 1982; Gastony and Darrow, 1983; Soltis, 1986) have shown that the products of these two genes are differentially expressed in the cytosol and the plastids. Because this enzyme is dimeric, individuals heterozygous at a TPI locus normally resolve as a three-banded pattern using standard starch gel electrophoretic techniques; individuals I Received for publication 1O November 1987; revision accepted 6 June 1988. This research was supported by NSFgrant BSR 86-0672. The authors thank Drs. Susan Bamum, Jan Jaworski, and Jack Vaughn for comments and assistance during the formulation of this paper. We also thank Elizabeth Southworth for her help in the laboratory. The authors are grateful to the three reviewers who provided helpful suggestions on and insights into novel interpretations of the TPI phenotypes observed. homozygous at TPI loci produce only a single band at each locus. Interlocus heterodimers are not known to occur in plants between TPI loci in different compartments (Gottlieb, 1982). Although TPI is normally encoded by two loci, a number of cases are known in which at least one of these TPI loci has been duplicated. Gottlieb (1982), for example, has shown that both cytosolic and plastid TPI have been duplicated subsequent to the origin of the genus Clarkia and that one or both of these duplications represent distinguishing features for most species in the genus. A characteristic of gene duplications in TPI and in other dimeric enzymes is the presence of one or more sets of three nonsegregating bands: a case of apparent fixed heterozygosity. Examples ofthis apparent fixed heterozygosity have been found in a large number of pteridophytes including Lycopodium (Soltis and Soltis, 1988), Equisetum (Soltis, 1986), and nearly all members of the Polypodiaceae sensu lato examined to date (see Haufler and Soltis, 1986). In Lycopodium and Equisetum, the additional TPI bands are compartmentalized in the plastids, whereas the extra bands of the polypodiaceous ferns are cytosolic. Three hypotheses have been put forth to explain the peculiar three-banded pattern

Influence of the carcinogenic pollutant benzo[a]pyrene on plant development: Fern gametophytes

Polycyclic aromatic hydrocarbons (PAHs), ubiquitous environmental pollutants, are known to be biologically active in mammalian systems and are accumulated by plants. A few reports suggest that PAHs stimulate growth in plants and induce morphogenesis in plant tissue in culture. To investigate the growth altering abilities of PAHs in plants, polypodiaceous fern gametophytes were grown under sterile conditions on media containing a biologically active PAH, benzo[ a]pyrene (BaP), at doses ranging from 0.1 to 10.0 μg/ml. The growth pattern of polypodiaceous fern gametophytes enables alterations in growth and morphogenesis to be observed at the cellular level in an intact plant. Doses of BaP in the range 0.1–3.2 μg/ml enhanced the onset of the morphological transitions from 1-dimensional (1D) to 2-dimensional (2D) growth. This transition for BaP treated plants occurred after fewer cell divisions than the corresponding solvent and untreated controls. The low (0.1 and 0.32 μg) and high (1.0 and 3.2 μg) doses of BaP were found to accelerate and inhibit cell proliferation, respectively. The 10.0 μg dose was toxic and resulted in decreased germination of spores and reduced survival of plants. A slight but significant decrease in survival was also observed in ferns treated with 3.2 μg. This is the first example of PAH influencing cell differentation in a whole plant system.

Polypodiaceous Ferns of India

Polypodiaceous Ferns of India

Fern constituents. Onoceroid,.ALPHA.-onoceradiene,serratene and onoceranoxide,isolated from Lemmaphyllum microphyllum varieties.

α-Onoceradiene (I) and serratene (IV) were isolated and identified from a Polypodiaceous fern, Lemmaphyllum microphyllum var. microphyllum, while a new compound, onoceranoxide (VII), was obtained from var. obovatum as a main triterpenoid and its structure was established.