Species Of Polypodium Research Articles

Electrophoretic Evidence for Allopolyploidy in the Fern Polypodium virginianum

Polypodium virginianum comprises three morphologically similar cytotypes: diploid (2n = 74), triploid (2n = 111), and tetraploid (2n = 148). Previous cytological and morphological analyses suggested that tetraploid P. virginianum was actually of allopolyploid origin resulting from hybridization between diploid P. virginianum and another diploid Polypodium species. To test this, an electrophoretic investigation of diploid, triploid, and tetraploid populations of P. virginianum was undertaken. Analysis of eight enzymes showed 15 loci common to all three cytotypes. Fixed heterozygosity due to the presence of two additional isozymes was detected in triploid and tetraploid P. virginianum. This increase in isozyme number in the tetraploid is suggestive of the addition of two divergent genomes in its formation. One of the parental genomes involved in the formation of tetraploid P. virginianum clearly is diploid P. virginianum; the second parental genome appears to be P. amorphum. Electrophoretic data are in agreement with 1) an allopolyploid origin of tetraploid P. virginianum, and 2) formation of the triploid cytotype via hybridization between diploid and tetraploid P. virginianum.

Notes on XPleopodium and Pleopeltis in Tropical America

Interpretation of the polypodioid ferns has been a classic problem for pteridologists. The groupings are, with some exceptions, fairly clear, but whether they should be treated as subgenera of Polypodium or as distinct genera is a matter of considerable disagreement. There seems to be growing acceptance of their recognition as distinct genera (Smith 1981, 1985; Tryon & Tryon, 1982; Lellinger, 1985; Mickel & Beitel, in press), although some authors continue to recognize Polypodium in a broad sense (Proctor, 1977, 1985; Stolze, 1981). Some of the splinter genera in America (e.g., Campyloneurum, Niphidium) stand well apart from Polypodium s.s., but others are apparently very closely allied to Polypodium. This is especially so in regard to Pleopeltis, some members of which hybridize with species of Polypodium s.s. The best known example of this is Polypodium x leucosporum (=Polypodium lanceolatum x P. thyssanolepis), which was pointed out by Vareschi (1969) and described in detail by Wagner and Wagner (1975), who treated it and its parents within Polypodium. Recently, Anthony and Schelpe (1985) described a similar case in southern Africa, in which Pleopeltis macrocarpa (Bory ex Willd.) Kaulf. (=Polypodium lanceolatum) crosses with Polypodium polypodioides var. ecklonii (Kunze) Schelpe. The authors gave a hybrid intergeneric name to their hybrid species, x Pleopodium simianum Anthony & Schelpe. In our studies on the ferns of Oaxaca, Mexico (in press), we have seen specimens from various parts of Mexico that involve several members of these two genera. Most of the hybrids have binomials under Polypodium. The purpose of this paper is to make several new combinations under x Pleopodium and Pleopeltis, and to clarify the putative parentage of the hybrids.

Fern constituents: Eupha-7,24-diene and (20R)-dammara-13(17),24-diene, tetracyclic triterpenoid hydrocarbons isolated from Polypodium species.

From the fresh leaves of polypodium someyae eupha-7, 24-diene and from the fresh rhizomes of P. fauriei (20R)-dammara-13 (17), 24-diene were obtained and characterized. These hydrocarbons are the first derivation from a natural source. They are rather unstable in the air.

The perispore in Polypodium and related genera (Polypodiaceae)

Light and scanning electron microscopy (SEM) have been used in a study of spore surface features in Polypodium and in the related genera Crypsinus, Solanopteris, and Synammia. Under SEM, spores of nearly all taxa exhibit deposits interpretable as perispore. Spores of Polypodium species are characterized by an exospore which varies from smooth to verrucose or with knoblike verrucae, and by perispore deposits which vary from thin, tightly affixed layers to thick, platelike, highly ornamented layers. Folded or "winged" perispores are present in several species and some species exhibit two perisporial layers which are dissimilar in structure. Sporoderm features of Synammia are similar to those exhibited within Polypodium; however, the perispores of Crypsinus and Solanopteris are spinulose. Although the majority of species investigated do not have elaborate or well-developed perispores, sufficient diversity is present to suggest that this feature could be useful in delineating some of the natural groups in this complex family.

Notes on Some Pleopeltis and Polypodium Species of the Chihuahuan Desert Region

Notes on Some Pleopeltis and Polypodium Species of the Chihuahuan Desert Region

A New Species of Microgramma from Argentina

The systematic revision of Argentine Polypodiaceae (s. str.) and Grammitidaceae that was published some years ago (de la Sota, 1960) included in the genus Microgramma three species: M. lindbergii (Mett.) de la Sota, M. squanzulosa (Kaulf.) de la Sota, and M. vacciniifolia (Langsd. & Fisch.) Copel. Investigations have continued concerning the naturalness of the genus Microgramma, its delimitation, and its relationships with other groups of neotropical Polypodiaceae, especially with Pleopeltis and certain other simple-bladed species of Polypodium. All this will be discussed in a future publication, giving various morphological details for as many species as possible of this problematical genus. De la Sota (1960, pp. 69-71) mentioned the heterogeneity of M. vacciniifolia specimens, especially those found in the forests along the banks of the Rio de La Plata and its minor tributaries. Between those specimens and the ones from the remainder of the species' area (Brazil, Paraguay, eastern Bolivia, and northeastern Argentina) there are differences in rhizome scale morphology and in frond size, texture, dimorphism, and venation. A recent, careful analysis of the specimens growing in the forest communities along the Rio de La Plata, or on cultivated trees in its vicinity, has led to the conclusion that these specimens are a new species directly related to M. squamulosa and M. vacciniifolia. This newly recognized entity is fertile and is entirely intermediate in morphology between the aforementioned species. This fact, coupled with its geographic distribution and with a significant difference in stomate and spore size, are arguments in favor of a hybrid origin for this taxon, followed presumably by chromosome doubling. The characters which distinguish the hybrid and its putative parents are as follows:

Occurrence of a Winged Perispore in a New World Species of Polypodium

Spores ofPolypodium chnoodes Spreng. were found to possess a large winged perispore surrounding the exospore. This character had hitherto been found only in the closely related families of the aspidioid-dennstaedtioid complex. Its presence in a species ofPolypodium is another example of the remarkable parallelisms which occur in ferns.

New Chromosome Numbers in Polypodium L.

species of Polypodium occur. Manton (1951) reported diploid (n=37) counts for three of them, P. glycyrrhiza, P. hesperium, and P. scouleri, and a tetraploid count (n=74) for the fourth, P. californicum. Knobloch (1962) recently reported a tetraploid count for P. hesperium. New counts of P. californicum and P. hesperium from areas removed from the localities where earlier counts were made are presented here. METHODS AND MATERIALS Methods of slide preparation were identical with Manton's (1950) except that aceto-orcein was used instead of acetocarmine. Both boiling and squashing were used on each slide to good advantage. Living rhizomes were collected in the field and cultivated in the greenhouse until suitable fertile fronds appeared. Material was fixed in a 6:3:1 solution of absolute ethanol:chloroform: glacial acetic acid. All stages of division were found in material fixed in the afternoon. RESULTS

Contributions to the cytology and taxonomy of species of Polypodium in Europe and America. I. Cytology

The paper summarizes the present state of cytogenetic knowledge of Polypodium in Europe and some parts of America, and discusses the evidence regarding the phyletie relations of the various taxa. New observations on wild European hybrids include (a) descriptions and analysis of chromosome pairing in two tetraploids believed to represent crosses between diploid and hexaploid, and (6) further observations on chromosome pairing in triploids. All possible types of hybrid between the three European taxa have been synthesized and chromosome pairing in them seen. In every case there is close agreement with the corresponding observations on wild plants. It is concluded that the hexaploid is in origin an amphidiploid hybrid between the European tetraploid and the European diploid as previously postulated, and that the two parental types are not otherwise closely related. Specific recognition for the three European cytotypes is recommended and names for them have been found in accordance with the International Rules of Nomenclature. A parallel study of Polypodium virginianum from eastern America has shown that diploid P. virginianum is able to pair chromosomes with one of the genomes present in European tetraploids and hexaploids. This genome is also present in tetraploid P. virginianum from eastern America as half the nuclear content. It is therefore concluded that not more than four different genomes are present, separately or combined, among the various taxa discussed, two of which have been identified singly in existing diploid species on opposite sides of the Atlantic. Preliminary observations on a diploid from western America (P. glycyrrhiza) have shown that this also is related to at least one of the European polyploids although the exact nature of the relationship is still under study.

Contributions to the cytology and taxonomy of species of Polypodium in Europe and America. II. Taxonomy

GENERAL SUMMARY 1 The nomenclatural problems involved in carrying out the recommendations made in part I that specific rank be given to the three European cytotypes of Polypodium are discussed and reasons are given for the names selected. 2 The names recommended are: P. vulgare L. sens. strict. for the tetraploid, P. australe F6e for the diploid and P. interjectum sp.nov. for the hexaploid. 3 A Latin diagnosis is provided for P. interjecturn and a recommended paratype for it is no. 4757 in the Hortus Cliffortianus in London of which a photograph is reproduced. Holo- and isotypes from a cytologically worked specimen have been deposited in the national herbaria at the British Museum (Natural History) and Kew under the collector's number: Shivas 342 from St Cyrus, Kincardineshire. 4 The various morphological criteria available for distinguishing these species in the field or herbarium are discussed in the light of experience of many plants grown in culti- vation as well as in the wild state. The more important morphological criteria are sum- marized in the form of a key. 5 Maps are provided to record the present state of knowledge regarding the geo- graphical distributions of the three species in Europe.

The Problem of Polypodium virginianum

linas to Nova Scotia and Canada. It is perhaps less commonly known that it is distinguished from all other temperate species of Polypodium by the presence of very peculiar glandular organs (paraphyses) among its sporangia. These can be detected with a hand-lens, though they require the low power of a microscope for details to be properly seen, since each paraphysis is about the size of a sporangium but with a number of glandular hairs on its head (pl. XIV). The function of these curious organs is not well understood, but they were discovered to be of very constant occurrence of Martens2 and his collaborators who have not only used them for taxonomic purposes but have also plotted their geographical distribution. Besides eastern North America, where they are always to be found, populations of Polypodium with similiar paraphyses occur again in China, providing a

An Overlooked North American Fern

Hooker called this very peculiar species of Polypodium (sect. Drynaria, Fee, but probably a Microgramma of Presl). It does have more resemblance to Microgramma than to anything else, and this may be its affinity, but the rather fleshy, herbaceous texture, and the laxly and irregularly anastomosing veins, and the paucity of included veinlets make it seem unreasonable to include it in that genus. The tubers are remarkable; but I would not regard them as by themselves justifying generic distinction for the species, no more than do those of Nephrolepis cordifolia.

On the Names of Three Jamaican Species of Polypodium

On the Names of Three Jamaican Species of Polypodium