Species Of Ophioglossum Research Articles

Sequencing of the complete plastome of the thermal adder’s-tongue fern, Ophioglossum thermale Kom. (Ophioglossaceae)

The Ophioglossaceae family, one of the oldest orders of extant ferns, exhibits diverse morphological and chromosomal characteristics. This study presents the first complete plastome sequence of thermal adder’s-tongue fern (Ophioglossum thermale), a species renowned for its antioxidant properties in traditional Chinese medicine. Our analyses revealed 27 simple sequence repeats (SSRs) in the plastome, with variations in SSR frequencies compared to related genera. Our phylogenetic analyses placed O. thermale within the Ophioglossum s.s. clade, supporting previous studies and suggesting polyphyly within the genus Ophioglossum based on the sensu PPG I system. The enlarged noncoding regions in fern organelles (ENRFOs) resulting from foreign DNA insertions in O. thermale were identified in the ycf2-trnH and trnT-trnfM regions, similar to other Ophioglossum species. ENRFOs were found at the LSC and SSC, but not in IRs in Ophioglossaceae. Consequently, foreign DNA insertions and lineage-specific SSRs shed light on plastome evolution in the Ophioglossaceae family.

Ophioglossum isanense sp. nov. (Ophioglossaceae, Pteridophyta) from Thailand

A new species of Ophioglossum, O. isanense, from Northeast Thailand is described and illustrated. It may be diagnosed from other congeners by a combination of morphological characters including: its smaller size, cylindrical rhizome, stoloniferous roots, brownish green common stalk and trophophylls, the presence of persistent leaf sheath at the top of the rhizome and by the unique structure of spores. Molecular study also supported it as a distinct species. A summary of the ecology and an IUCN conservation status of the new species are provided.

Occurrence of <I>Ophioglossum rubellum</I> (Ophioglossaceae) in India

State of Gujarat is known for its different climatic conditions starting from moist deciduous to pure desert conditions. That could be one of the reasons that out of 22 species reported from India, nearly 16 species of Ophioglossum are found in the Gujarat state. In last monsoon's field survey, an interesting reddish coloured Ophioglossum was collected from the Jambughoda wildlife Sanctuary. After critical examination it is identified as O. rubellum (an African element) and reported as extended distribution record for India. Earlier it was misidentified as O. indicum, which is now corrected here. The detailed taxonomic account, distribution, conservation status, photographic evidences and comparative account is also provided herewith.

Comparative phylogenetics of some species of Ophioglossum L. (Ophioglossaceae: Pteridophyta) in India with comments on evolutionary significance of high palaeoploidy and rare morphological traits

The genomic constitution of the genus Ophioglossum is complicated because of its being geologically ancient and of long evolutionary history. A lot of plants of the same and different species resemble each other as well as show significant differences among morphological characters among themselves. Many of the new species described have exhibited several unknown features not observed in any species of the genus so far. In this paper, we wish to emphasize that mere observations on shape and size of trophophyll (leaf) and rhizome, should not be taken reliably in delimiting different species of the genus Ophioglossum because of several variations already reported for many species. Preference should be given to exine ornamentation of spores as emphasized by the present study. Detailed observations on exine ornamentation of spores under SEM have offered precious and distinctive features; semi-tuberculate, beaded strings, and stripped exines are a few forms of spore ornamentations offering clear distinction among species. Long chains of circulate-alete (round alete) spores, sometimes linear tetrads as described hereunder in Ophioglossum aletum are novel features exclusively confined to this species. Comparative chromosome profiles of many species described earlier do not offer any significant support to the identity except in O. eliminatum, which has the lowest chromosome count (n = 90). This appears that since almost all species possess intraspecific polyploidy, the intragenomic variability must be loaded with interspecific hybridization contents including chromosomal aberrations. Quite possibly, this may be one of the reasons that homologous chromosomes rarely form trivalents and multivalents during early meiotic stages, despite the fact that palaeoautoploidy must have resulted in copying homologous chromosomes. In recent years, repeated phylogenetic analysis of chloroplast rbcL have revealed that many species in India appear to be offshoots of a vulgatum clade which are likely to be the hybridization products involving O. costatum, O. vulgatum, O. reticulatum, and also including of other interspecific hybridizations. It is remarkable to mention that some of the new taxa published by us, viz. O. eliminatum, O. indicum, O. aletum and O. chalonerii (unpublished), explicitly show distinct phylogenetic relationship maintaining independent genomic identity. Furthermore, each new species shows some rare uniquely confined trait not possessed by any other species of the genus. These morphological traits also suggest that the plants may be expressing extremely rare genic-combinations which might have been brought forth due to autopolyploidy and/or allopolyploidy (hybridizations) during the past few decades. Obviously, we will need a multidisciplinary approach (morphological, anatomical, biochemical) in order to identify different species of Ophioglossum with new and unusual genomic identity and also to understand possible evolutionary mechanisms undergoing within the genome.

Revealing a new species of Ophioglossum (Ophioglossaceae-Pteridophyta) from India with palynological and phylogenetic implications

ABSTRACTIn recent years, Indian Ophioglossum L. taxonomy and systematic are receiving increasing interest from pteridologists as India has very rich germplasm of the genus. We present hereunder a new species of the genus Ophioglossum (Ophioglossaceae) from the marshy areas of southern region of Gujarat state, India. Ophioglossum hitkishorei sp. nov. can be diagnosed from other congeners by a combination of its smaller size, globose to subglobose, non-stoloniferous rhizome, number of trophophylls up to six, the absence of persistent leaf bases at top of rhizome and by very unique structure of spores. Spores are typically characterized by possessing granules deposition as exine strings bound around spores on the distal face and granulate assemblage on the proximal face of triradiate spores observed under SEM and also clearly distinct under light microscopic observations. As far as known, beaded strings of exine ornamentation have never been observed in any species of Ophioglossum in the world flora. Molecular study, based on two chloroplast DNA sequences trnL-F and psbA-trnH, also strongly supports O. hitkishorei sp. nov. as a distinct new species.

Taxonomic significance of morphological characters of spores in the family Ophioglossaceae (Psilotopsida)

Primary and secondary ornamentation of spores of ferns of the family Ophioglossaceae are important characters, used in the taxonomy of this group. Considering the small number of published data on those characters in the Ophioglossaceae from Central and Eastern Europe, this study aimed (1) to describe morphological characters of spores of Botrychium and Ophioglossum species and to assess their taxonomic significance; (2) to analyse variation in spore size between and within species of these genera, based on specimens from various habitats and geographic locations; and (3) to create a key to species identification based on the diagnostic characters of the spore ornamentation. We examined spores of 6 species from 16 localities in Central and Eastern Europe. Results of cluster analysis based on morphological characters of spores indicate that the species form well-defined groups, partly reflecting the systematics of the Ophioglossaceae. A comparison of our results with data from North-West Europe and North America shows differences in some species. The broad range of variation in the size of spores from European populations, in comparison with American ones, may be linked with polyploidy of the studied species. Our findings will help in identification of spores of the family Ophioglossaceae in palynological and palaeobotanical studies.

Genetic Diversity in the Homosporous Fern Ophioglossum vulgatum (Ophioglossaceae) from South Korea: Inference of Mating System and Population History

It is generally believed that the members of Ophioglossaceae have subterranean, potentially bisexual gametophytes, which favor intragametophytic selfing. In Ophioglossaceae, previous allozyme studies revealed substantial inbreeding within Botrychium species and Mankyua chejuense. However, little is known about the mating system in species of the genus Ophioglossum. Molecular marker analyses can provide insights into the relative occurrence of selfing versus cross-fertilization in the species of Ophioglossum. We investigated allozyme variation in 8 Korean populations of the homosporous fern Ophioglossum vulgatum to infer its mating system and to get some insight into the population-establishment history in South Korea. We detected homozygous genotypes for alternative alleles at several loci, which suggest the occurrence of intragametophytic self-fertilization. Populations harbor low within-population variation (% P = 7.2, A = 1.08, and H (e) = 0.026) and a high among-population differentiation (F (ST) = 0.733). This, together with the finding that alternative alleles were fixed at several loci, suggests that the number and size of populations of O. vulgatum might have been severely reduced during the last glaciation (i.e., due to its in situ persistence in small, isolated refugia). The combined effects of severe random genetic drift and high rates of intragametophytic selfing are likely responsible for the genetic structure displayed by this homosporous fern. Its low levels of genetic diversity in South Korea justify the implementation of some conservation measures to ensure its long-term preservation.

Observations onOphioglossum eliminatum(Pteridophyta: Ophioglossaceae) with comments on the lowest chromosome number in the genus

Population biology data collected during 1995–2009 from more than a dozen localities in Central India have revealed that both the interspecific as well as intraspecific chromosome variations are inherent in many species of Ophioglossum L. The lowest count of chromosome recorded for any plant of Ophioglossum eliminatum Khandelwal et Goswami reported to be n = 30 chromosomes has not been confirmed even in a single spore mother cell or in any mitotically dividing root tip cell. This is emphatically emphasised to be characterised by n = 86±2 chromosomes little lower than originally suggested 90±2 chromosomes. Therefore this is reemphasised that lowest chromosome count for the genus is n = 86, not n = 30 as claimed earlier. Somatic chromosomes from root tip squashes and microtome sections of root tip cells stained with haematoxylin clearly reveal polysomaty (chromosome variations in multiples within the same tissue) in O. eliminatum and O. costatum, which have been probably ignored by earlier workers. Additionally, typical epidermal feature of linear splitting of cells to form several openings in the mesophyll, inherent and expressed only by leaves of O. eliminatum has been found to be a diagnostic trait of the species collected from original localities in Shivpuri forest in Central India and far away in Rajasthan in Western India. As far as known, no living or a fossil leaf has ever shown such natural tearing of the mesophyll tissue.

Chromosome evolution in the genus Ophioglossum L.

Cytological observations on eleven species of Ophioglossum revealed low gametic (n) chromosome numbers of 30, 34 and 60 in populations of O.eliminatum, contrasting with an earlier report of n= 90 in the same species. The rest of the species is based on n=120.Cytologically studied species of Ophioglossum exhibit a range of chromosome numbers from n = 30 in O.eliminatum to n=720 in O.reticulatum. The weighted highest common factor (HGF) from all the reported chromosome numbers in twelve species was found to be 30. This number is proposed as the palaeobasic chromosome number for the genuS. Reported chromosome numbers which are not multiples of 30 were subjected to sequential analysis, yielding three distinct ultimate base numbers, 4, 5 and 6, which can produce n= 30 in seven different ways. The neobasic number, n= 120, appears to have arisen through various combinations and permutations of these, theoretically 2401 routes; only a relatively few of these routes exist today, suggesting that extreme selection has been exerted against the majority, and further suggesting that Ophioglossum represents an evolutionary dead end through repeated cycles of polyploidy and is possibly at the verge of extinction. The stoichiometric model of evolution, which derives the various chromosome numbers possessed by the twelve species from the basic and ultimate basic chromosome numbers, is used to explain chromosomal evolution in the genus.

Germination of Helminthostachys Spores

For nearly a century the spores of the Ophioglossaceae have been sown, but few investigators have succeeded in germinating them (Boullard, 1963). Campbell (1895, 1907) was the most successful in germinating spores of the Ophioglossaceae on soil. He reported the early stages of germination of spores of Botrychium virginianum (Campbell, 1895) and of three species of Ophioglossum (Campbell, 1907). An earlier report on spore germination in B. ternatum by du Buysson (1889) remains in question (Whittier, 1981) because the gametophytes that developed had essentially the same morphology as gametophytes of leptosporangiate ferns. More recently, spores of Botrychium and Ophioglossum have been germinated in axenic culture (Whittier, 1972, 1981; Gifford & Brandon, 1978). These spores germinated in the dark on nutrient media containing minerals and sugar. In some cases, the spores took 3-4 months to germinate under these conditions (Whittier, 1981). The mature gametophyte of Helminthostachys, the third genus of the Ophioglossaceae, has been described from nature (Lang, 1902; Nozu, 1961; Pant et al., 1984). It usually has a long, thick, cylindrical axis with numerous short lobes at its base. The lobes have apical meristems and appear to be short branches (Pant et al., 1984). The basal region of the gametophyte contains the mycorrhizal fungus and the cylindrical portion bears the gametangia. Spore germination and early stages of gametophyte development are unreported for Helminthostachys. Since germination and gametophyte development in Botrychium and Ophioglossum have been studied with the techniques of axenic culture, the aim of this study was to use these techniques to determine the conditions that promote germination and early gametophyte development in Helminthostachys.

The morphological nature of the fertile spike in the Ophioglossaceae

A study of a large collection of specimens belonging to 12 species of Ophioglossum revealed the presence of many abnormal structures in the tropophyll and the spike. These anomalous structures suggest that the fertile spike of Ophioglossum is derived from the modified pinnae of a compound leaf. Compound vegetative leaves are possessed by its allies Botrychium and Helminthostachys.

Gametophytes and Young Sporophytes of Ophioglossum crotalophoroides Walt

The lens-shaped, dorsiventral gametophytes of Ophioglossum crotalophoroides are superficially different from the cylindrical gametophytes of other species of Ophioglossum. However, they have the same features as other Ophioglossum gametophytes (fundamentally axial organization, radially symmetrical apical meristem, radial distribution of gametangia) except that the cylindrical axis is reduced in length. Young sporophyte development is unique in the genus: all primary organs clearly arise from the embryo and develop simultaneously. The length of the life cycle of O. crotalophoroicles is considerably shorter than that of some other species in the Ophioglossaceae. A timetable for gametophyte and young sporophyte development is postulated. Spores germinate soon after they are released in the spring, and mature gametophytes develop by the next growing season. Fertilization occurs approximately one year after spore dispersal, and after two years, the photosynthetic first leaf of the young sporophyte emerges.

GAMETOPHYTES AND YOUNG SPOROPHYTES OF OPHIOGLOSSUM CROTALOPHOROIDES WALT.

The lens‐shaped, dorsiventral gametophytes of Ophioglossum crotalophoroides are superficially different from the cylindrical gametophytes of other species of Ophioglossum. However, they have the same features as other Ophioglossum gametophytes (fundamentally axial organization, radially symmetrical apical meristem, radial distribution of gametangia) except that the cylindrical axis is reduced in length. Young sporophyte development is unique in the genus: all primary organs clearly arise from the embryo and develop simultaneously. The length of the life cycle of O. crotalophoroicles is considerably shorter than that of some other species in the Ophioglossaceae. A timetable for gametophyte and young sporophyte development is postulated. Spores germinate soon after they are released in the spring, and mature gametophytes develop by the next growing season. Fertilization occurs approximately one year after spore dispersal, and after two years, the photosynthetic first leaf of the young sporophyte emerges.

The Gametophytes of Ophioglossum palmatum L.

Gametophytes of the epiphytic species Ophioglossum palmatum L. are described for the first time, bringing the number of Ophioglossum species with known gametophytes to 11. Although somewhat unusual in terms of (a) degree of branching, (b) the marked expansion of the basically cylindrical axis in some cases, and (c) production of stout, papilla-like rhizoids, the gametophytes of O. palmatum are more similar to other Ophioglossum gametophytes than they are to the gametophytes of Botrychium or Helminthostachys. Gametophyte characters do not provide strong evidence for placing O. palmatum into a separate genus, viz., Cheiroglossa. The gametophytes of O. palmatum most closely resemble those of the other epiphytic species in the genus, O. pendulum. This similarity suggests a need for a revaluation of modern taxonomies which, in general, treat the two species as only distantly related.

THE GAMETOPHYTES OF OPHIOGLOSSUM PALMATUM L.

Gametophytes of the epiphytic species Ophioglossum palmatum L. are described for the first time, bringing the number of Ophioglossum species with known gametophytes to 11. Although somewhat unusual in terms of (a) degree of branching, (b) the marked expansion of the basically cylindrical axis in some cases, and (c) production of stout, papilla‐like rhizoids, the gametophytes of O. palmatum are more similar to other Ophioglossum gametophytes than they are to the gametophytes of Botrychium or Helminthostachys. Gametophyte characters do not provide strong evidence for placing O. palmatum into a separate genus, viz., Cheiroglossa. The gametophytes of O. palmatum most closely resemble those of the other epiphytic species in the genus, O. pendulum. This similarity suggests a need for a revaluation of modern taxonomies which, in general, treat the two species as only distantly related.

Sexual Reproduction in Ophioglossum crotalophoroides

In contrast to Botrychium and Helminthostachys, which reproduce solely by sexual means, the genus Ophioglossum is characterized by the formation of clones. Individual plants may give rise to several others by the process of root budding. Sexual reproduction, on the other hand, is considered a relatively rare event. In this paper I wish to discuss a species of Ophioglossum which apparently lacks the ability to reproduce asexually and must rely entirely on the formation of gametophytes to produce new individuals. The Bulbous Adder's-tongue, Ophioglossum crotalophoroides Walt., is a plant of disturbed, sandy habitats with a geographical range extending from South Carolina to the Falkland Islands (Clausen, 1938, 1948). The structure and development of the sporophyte of this species easily qualify it as one of the most remarkable, yet little-known, pteridophytes in the world. Its most distinctive feature involves growth of the tuberous rhizomes in an overall downward direction (Fig. 1), in contrast to the more usual condition of upward or horizontal growth characteristic of the stems of ferns and other vascular plants. This peculiar phenomenon can readily be observed in the field by examining the under-surfaces of the stems. Light, tan-colored streaks (Figs. 2, 3) indicate areas of tissue eruption and emergence. Young tissues, formed by the activity of an apical region that is sunken deep within the stem, push outward and downward as growth proceeds (Fig. 1). In contrast to the apparently active stem bases, the upper, older regions are dark in color and partially necrotic. New roots are initiated near the bases of the stems. This type of upside down growth strongly contrasts with that of most other species of Ophioglossum. Petry (1913) provided the only existing account of the growth and development of the stems of this interesting species.2 In March, 1972, I visited several localities in north central Louisiana with R. Dale Thomas and W. H. Wagner, Jr., in search of 0. crotalophoroides. My primary objective was to collect a series of rhizomes of different ages for use in developmental studies. I was also anxious to discover the previously undescribed gametophytes of this species. It seemed likely that gametophyte characters would compliment those from the sporophyte in elucidating the evolutionary relationships of the species. Furthermore, there is a general need for more information about the gametophytic generation of Ophioglossum. Gametophytes are known from a mere seven of the approximately 30 to 40 species in the genus (Boullard, 1963; Mesler, 1972).

Cytology of some species of the Ophioglossaceae in India

Chromosome numbers in six species ofOphioglossum available in Poona and inHelminthostachys zeylanica L. obtained from Kerala are given.O. nudicaule L.,O. gramineum Willd.,O. pedunculosum Prantl (sensu non-Desv.) andO. fibrosum Schum. were found to haven=120 chromosomes.O. aitchisoni d’Alm. had 210–215 bivalents, andO. reticulatum L. hadn=420. Of these the chromosome number inO. peduculosum was not reported before. Meiotic cycle in this species showed some irregularities such as bridge formation in some cases at anaphase I. The paper further discusses the significance of polyploidy observed inO. nudicaule and traces the evolutionary trends seen in the genus on the basis of the chromosome numbers. There exists some sort of correlation between the size of plants and their chromosome numbers. No variation in the number of chromosomes in different plants of the same species growing in different localities was observed. On the basis of the chromosomal analysis, it seems thatO. nudicaule, O. gramineum group is more primitive andO. aitchisoni, O. reticulatum groups more advanced. This agrees with the conclusion drawn by one of us (Mahabale, 1965) in this regard, on the basis of the morphology of species.

Development of Stomata in some Ophioglossum Species

Development of Stomata in some Ophioglossum Species

Studies on the Cytology and Phylogeny of the Pteridophytes

1. A critical cytological investigation of nine species of Ophioglossum (including several cytological and geographic races), one species of Botrychium and the monotypic Helminthostachys has been made.2. The lowest haploid number for Ophioglossum is n=120 and for Helminthostachys, n=94.3. Almost all the species of Ophioglossum investigated in the present study (excepting the aneuploid series in O. reticulatum and perhaps O. vulgatum) are found to form a polyploid series based on the haploid number n=120.4. O. reticulatum L. is shown to have the highest chromosome number yet recorded in any species (n=c. 630, 2n=c. 1260).5. The basic chromosome number of the Ophioglossaceae is postulated to be 15.6. Evidences of chromosome numbers obtained from this study show the probability that there is some parallelism in the cytological evolution of the Ophioglossaceae and the Schizaeaceae. Both Ophioglossum and Schizaea exhibit very high chromosome numbers. The basic number 15, characteristic of the Ophioglossaceae, is also shared by Lygodium, the most primitive genus of the Schizaeaceae.7. Cytological evidence is in favour of regarding Botrychium as the most primitive of the three genera while Helminthostachys is intermediate and Ophioglossum the most specialised.8. There is no cytological support for the segregation of species of Botrychium and Ophioglossum into subgenera or for raising these subgenera to generic status.9. It is suggested that the greater percentage of polyploids as well as higher grades of polyploidy encountered in South Indian races of Ophioglossum may be related to the fact that Peninsular India is geologically one of the oldest land masses with a continued vegetation cover for a very long geological period. This suggestion is incidentally supported by evidences of chromosome numbers from ancient genera like Tmesipteris and Phylloglossum from Australia which also represents a very old geological formation.10. The taxonomic delimitation in species like O. reticulatum, O. petiolatum and O. vulgatum is seen to be very artificially drawn.11. Taxonomic revision in the light of cytology is necessary for O. nudicaule.

Cytology of <i>Ophioglossum coriaceum</i> A. Cunn

Studies into the cytological behaviour in the genus Ophioglossum have been undertaken especially from a cytogeographical and cytotaxonomical bias. The present investigation reveals the haploid chromosome number in an Australian population of Ophioglossuon coriaceum A. Cunn. to be 510 and it includes 10-14 very small bivalents. This number is incidently a mul-tiple of 15 and lends further support to Ninan's (1956a) suggestion that 15 is probably the common base number of the family Ophioglossaceae. -However, keeping in view the discrepancies in chromosome numbers in some Ophioglossum species, in particular O. polyphyllum (cf. Table 1) and Helminthostachys (n=94, Ninan Lc) it seems desirable to make further enquiries in this direction especially as Stebbins (1950) has also pointed out that the higher the number the more are the ways in which it can be compounded. Apart from repeated allopolyploidy the present writer, on the basis of the existence of multivalents in a form of O. vulgatum (Verma 1956), emphasizes also the role of autopolyploidy. Furthermore, vegetative reproduction is responsible for supporting diverse chromosomal constitution and the initial sterility arising out of autopolyploidy.Taxonomic status of Ophioglossum coriaeemn is discussed in the light of Claussen's (1938) morphological observations and the available cytological data on the related species O. lusitanicum (Manton 1950b and Ninan 1956a) as well as other widely distributed species like O. vulgatum (Verma 1956). It is suggested that O. coriaceum should not be treated as a distinct species but rather be merged within the polymorphic O. lusitanicum. Pending fur-ther studies on more parts of its range, it is at present regarded as a distinct cytogeographical race and thus be treated as a ssp. of O. lusitanicum, as pro-posed earlier by Claussen on the basis of morphology and geographical distribution.Based on observations on O. vulgatum and O. lusitanicum (sensu Claussen, 1938), it is suggested that the genus Ophioglossum as a whole be regarded as a group of facultative apomicts. Furthermore, the species concept in the genus should be on more or less similar lines as adopted for apomictic angiosperms (cf. Stebbins 1950).Present cytological data reveals that the species with wider distribution show numerous cytological races as well as high number. Furthermore, there is probably a gradual increase in the chromosome number from Northern to Southern latitudes. This formulation, however, needs further study on widely distributed species.