Staining and osmotic properties of young gametophytes ofPolypodium vulgare L. and their bearing on rhizoid function

Summary The rhizoids of gametophytes ofPolypodium vulgare L. rapidly absorb vital stains whereas the protonemal cells are impermeable to these stains, which can only enter the cells from the rhizoids. The protonemal cells which bear rhizoids were found to have a slightly higher osmotic equivalent than did the rhizoids or the protonemal cells on either side. From the results of several staining procedures it was demonstrated that the rhizoid walls contain free carboxyl groups and thus possess cation exchange properties. Most of the carboxyl groups are probably present in a yellow-brown wall matrix substance, which shows high resistance to acid and alkali extraction. The precise nature of this substance has not been determined but it could be an acid mucopolysaccharide. Carboxyl groups are detectable in the protonemal cell walls only after saponification and are probably esterified in the untreated wall. Several other chemical and physiological differences were found between the rhizoids and the protonemal cells and it was concluded that the specific properties of the rhizoids are related to their function as organs of uptake.     

Studies of protonemal morphogenesis in mosses. IX. Discelium nudum: exquisite pioneer of unstable clay banks

Abstract

The protonemal system of Discelium nudum produces a sward of unicellular, colourless, starch-filled rhizoidal tubers ca 1 cm below the surface of unstable clay banks. These short-lived and desiccation-intolerant diaspores are exposed on new clay surfaces following winter exfoliation of the original substratum. Their abundance and rapid germination appears to be a reproductive strategy giving Discelium a competitive advantage in this highly unstable habitat. The rounded, thin-walled, non-gemmiferous chloronemal filaments and colourless rhizoids of Discelium suggest affinities with the Funariaceae and the Gigaspermaceae. An early report of multicellular tubers in Discelium is most probably due to misinterpretion of the large starch grains, up to 20 μm in diameter, as cells within the unicellular tubers.     

Protonemal Morphogenesis of the Moss Tetraphis pellucida Hedw. in Culture and in the Wild

In axenic culture, the protonemal filaments of Tetraphis pellucidaderived from either spores and gemmae, or excised stems andleaves, share a mixture of attributes of chloronemata and caulonemata.Indirect immunofluorescence reveals that the tip cells containcortical and endoplasmic arrays of microtubules at interphase,and phragmoplasts associated with cell plate formation, butpre-prophase bands are absent. Protonemal plates originate fromthe same sites as filamentous protonemal side branches or directlyfrom young gemmae or excised stem fragments. These plates havea cylindrical base, the latter producing a single gametophorebud, and a unistratose lamina. The gametophores produce gemmacups in culture with the vegetative life cycle taking approximately28 d. Gibberellic acid (GA₃) has no visible effect on protonemal morphogenesiswhereas the auxin naphthalene acetic acid (NAA) suppresses plateand side branch formation. In the presence of kinetin the platesare callus-like and produce supernumerary buds. Abscisic acid(ABA) induces malformed plates and filaments with swollen cells,similar to those found in ageing cultures. Rhizoids are produced in abundance from gametophores and protonemalplates in nature but were never seen in culture. In the wild,rhizoids produce numerous protonemal plates and occasional gametophorebuds. The former are the main source of new shoots. The filamentousprotonemal phase in nature mainly comprises upright filamentscontaining one or more abscission cells. The protonemal plates in Tetraphis are homologous with thosein the allied genus Tetrodontium but are very different fromthose in Diphyscium and Sphagnum. Differences between cultureand nature are attributed to lower nutrient levels and irradiancesin the wild. Tetraphis pellucida, protonema, moss, morphogenesis, immunocytochemistry, gemmae, tip growth, vegetative reproduction     

中国藓类植物无性繁殖体的初步观察

无性生殖在苔藓植物的生活史中起着重要的作用,并且常通过各种无性繁殖体来完成。无性繁殖体的形态常被用来辅助鉴定一些不育的藓类植物。本文通过对38种藓类植物的无性繁殖体进行显微观察,结果显示：无性繁殖体在不同的藓类植物之间已经过多次演化;无性繁殖体的形态在种内是相对稳定的,且与其着生位置、配子体的分枝方式密切相关,而与植物的系统位置以及生境并无直接的关系;无性繁殖体的颜色与其胞壁的厚度以及表面纹饰密切相关。此外,无性繁殖体的产生常常与假根、原丝体有共存关系。在研究中发现,藓类植物的无性繁殖体主要包括原丝体芽胞、无性芽胞（叶生芽胞、中肋芽胞、枝生芽胞）、芽体、假根芽胞和假根状块茎;其中原丝体芽胞和无性芽胞最为常见。     

New Vice-County Records

Abstract

Bryophytes and vascular plants used in traditional home-made nativity sets were studied in an area of the Asturian Region, northern Spain. The results revealed a surprising plant diversity, with 66 bryophytes, three ferns and 37 flowering plants utilized. Most species, collected among more attractive mosses, were used only occasionally or accidentally, whereas only four large pleurocarpous mosses, Thuidium tamariscinum, Eurhynchium striatum, Hypnum cupressiforme and Pseudoscleropodium purum, were widely used, providing the moss base of all the sets. Additionally, eleven mosses and four native flowering plants were frequently selected. The diversity of the bryophytes used in nativity sets of different sizes is analysed, and the deliberate selection of moss species during the collecting is discussed. Finally, it is verified that the collection of certain showy mosses from forests and peat bogs could affect local populations of these mosses and entails the accidental removal of rare or endangered species.     

Conserved function of Rho-related Rop/RAC GTPase signaling in regulation of cell polarity in Physcomitrella patens

Cell polarity is fundamentally important to growth and development in higher plants, from pollen tubes to root hairs. Basal land plants (mosses and ferns) also have cell polarity, developing protonemal apical cells that show polar tip growth. Flowering plants have a distinct group of Rho GTPases that regulate polarity in polarized cell growth. Rop/RAC signaling module components have been identified in non-flowering plants, but their roles remain unclear. To understand the importance and evolution of Rop/RAC signaling in polarity regulation in land plants, we examined the functions of PpRop and PpRopGEF in protonemal apical cells of the moss Physcomitrella patens. Inducible overexpression of PpRop2 or PpRopGEF3 caused depolarized growth of tip-growing apical cells. PpRop2 overexpression also caused aberrant cross wall formation. Fluorescent protein-tagged PpRop2 localized to the plasma membrane, including the cross wall membrane, and fluorescent-tagged PpRopGEF3 showed polarized localization to the tip region in apical cells. Thus, our results suggest common functions of PpRop and PpRopGEF in the tip-growing apical cells and the importance of a conserved Rop/RAC signaling module in the control of cell polarity in land plants.     

Gametophyte development and reproduction of the Asian fern Polystichum polyblepharum (Roem. ex Kunze) C. Presl (Dryopteridaceae,Polypodiopsida)

Abstract

The gametophytic generation of Polystichum polyblepharum (Dryopteridaceae), including spore germination, morphological development of the gametophytes, major vegetative features and reproduction strategies, was studied. Spore germination was of the Vittaria model and the developmental pattern was of the Aspidium model. Adult gametophytes were cordate and hairy, with unicellular hairs located at the margins and at the prothallus surface. The marginal ones were secretory. The gametophytes produced archegonia located in the central area between the notch and the rhizoids, but antheridia were never detected. Archegonia were of the normal type described for leptosporangiate ferns. Apogamous sporophytes appeared from a cellular outgrowth developed just under the apical notch. Initially, the outgrowth appeared completely surrounded by glandular hairs and scales, which persisted throughout the subsequent stages of leaf development.     

Circular arrangement of cortical microtubules around the subapical part of a tip-growing fern protonema

Summary Cortical microtubule arrays in tip-growing protonemal and rhizoid cells of the fernAdiantum gametophytes were observed by immunofluorescence microscopy. A circular arrangement of cortical microtubules was demonstrated around the subapical part of protonemal cells growing under red light conditions. However, such an arrangement was not found in growing rhizoids either by immunofluorescence microscopy or by electron microscopy. The different patterns of microtubule arrays around the apices of tip-growing protonemal and rhizoid cells suggest the possible existence of different mechanisms in regulating the cell diameter in the two types of cylindrical cell.     

Comparative spermatogenesis in the Jungermanniales (Hepaticae) I. Observations on the structure of the young spermatids of Cephalozia lunulifolia and Chiloscyphus pallescens

Abstract

A comparative analysis of the young spermatids of Cephalozia and Chiloscyphus reveals the organisation of the Jungermannialian blepharoplast to be basically the same as in other hepatics and mosses. Common features include the four-layered multilayered structure, the spatulate, asymmetrical anterior portion of the spline, and the staggered subapical insertion of the basal bodies, each with proximal triplet extensions. The range of spline widths in the Jungermanniales appears to be as great as in other groups of bryophytes and of no major taxonomic significance, but the position of the spline aperture may be more variable in hepatics than mosses. The lengths of the basal bodies are intermediate between those from unrelated taxa in other orders of hepatics.

However, the data also suggest the Jungermannialian spermatids exhibit many taxonomic variations and novel features. Whereas the left-lateral expansion of the spline in Cephalozia is common to most other bryophytes, a right-lateral expansion is peculiar to Marsupella. Chiloscyphus manifests an intermediate condition: its spline is unequally bilateral, the left-lateral expansion wider than the right. Lateral extensions of the lamellar strip beyond the spline in Cephalozia, Chiloscyphus and Marsupella have been previously recorded only in Anthocerotae. A posterior notch on the right hand side of the lamellar strip in Marchantiales is absent in Chiloscyphus and Cephalozia and has not been observed in the Metzgeriales.     

A review of the Gymnostomum calcareum Nees & Hornsch. complex (Bryopsida: Pottiaceae) in southern Europe and the Macaronesian Islands,including G. calcareum var. atlanticum var. nov.

Abstract

New taxonomic observations, based on rhizoidal and protonemal gemmae of material from southern Europe and the Macaronesian Islands, are given in this work for sibling taxa of the Gymnostomum calcareum Nees & Hornsch. complex. Gymnostomum calcareum var. atlanticum Sérgio from the Iberian Peninsula, Madeira and Azores is described as a new variety, and its diagnostic characters are described and illustrated. This moss has a bistratose margin in the upper parts of the perichaetial and vegetative leaves, and the perichaetial leaves are markedly acute. It is closely related to Gymnostomum lanceolatum Cano, Ros & J. Guerra, here reduced to a variety of G. calcareum. The occurrence of fusiform or claviform protonemal gemmae provides a diagnostic feature for the different taxa.     

Sinephropteris,a new genus of scolopendrioid ferns

A new genus of ferns,Sinephropteris, is described from southeast Asia. Its one species,S. delavayi (Franch.) Mickel, has most recently been placed inSchaffneria, an otherwise monotypic Mexican genus, but there is evidence that they are not closely related.     

Life on a deadly trap: Buckleria paludum,a specialist herbivore of carnivorous sundew plants,licks mucilage from glands for defense

Caterpillars of Buckleria spp. (Lepidoptera: Pterophoridae) have a unique feeding habit of eating trap leaves of carnivorous sundew plants (Drosera spp.). We observed the foraging behavior of Buckleria paludum on trap leaves of Drosera spp. and discussed how the moth species avoided being caught by trap leaves. In 81.5% (66/81) of encounters with glandular hairs on adaxial surfaces of Drosera trap leaves, B. paludum larvae licked mucilage and crawled on the processed hairs. The frequency of licking mucilage was significantly higher than the frequency of other behaviors such as eating glandular hairs, chewing bases of them without eating and ignoring when encountering secreted mucilage. Licking mucilage enables the caterpillars to move safely on trap leaves and prevents bending of glandular hairs.     

The development of the mucilage gland of two Japanese species ofAlaria

The genusAlaria possesses a structure known as the mucilage gland which appears mainly on the frond. This is also true ofUndaria. The mucilage gland ofUndaria usually originates from some of the epidermal cells. However, observations of plants ofAlaria at various stages indicate that glands originate not only in the surface layer. There are still other glands which are initiated by some cortical cells situated directly beneath the epidermis. In both, a refractive substance is gradually accumulated as these cells enlarge. The mucilage glands starting in the surface (the primary mucilage glands) resemble those ofUndaria in their development, whereas those in the cortex (the secondary mucilage glands) are quite analogous to the secretory cells ofLaminaria, etc., which secrete mucilage into a mucilage canal in the first stage. Thus,Alaria seems to constitute a link betweenUndaria andLaminaria, etc.     

Hymenostylium xerophilum,sp. nov., and H. gracillimum,comb. nov., two neglected European mosses and their molecular affinities

Abstract

Hymenostylium xerophilum is described as a new species from the European Alps. Molecular rps4 and ITS data support its recognition and elucidate its affinities to other species of the tribe Pleuroweisieae. It is closely related to H. gracillimum, comb. nov., which is based on the old and neglected Gymnostomum gracillimum, which replaces the recent name G. boreale. Both species share non-coloured to pale yellowish-brown rhizoids, stem central strand and indistinct sclerodermis, keeled leaves, and concave laminae in abaxial view. They differ from each other in leaf shape and several essentially quantitative characters. Sporophytes have never been found in H. xerophilum, but they are known from several localities in H. gracillimum. The former colonizes rather dry, sunny to half-shaded calcareous rocks, whereas the latter needs moist and shaded rock habitats and shows a preference for subneutral slate. At present, H. xerophilum is known only from the Alps (Austria, and a single site in Germany), where it is rather widespread in calcareous regions. H. gracillimum seems to be a distinctly rarer plant, to date known only from eight Austrian sites and one locality in Russian Karelia. Other published records under the name G. boreale have been wrongly attributed to this species. Lectotypes are designated for G. gracillimum and Gyroweisia acutifolia. A key to Hymenostylium and the genera of Pleuroweisieae in Europe is presented.

Thicker rhizoids of both species are covered with a thick, non-coloured protective layer and filled with oil-droplets and leucoplasts. They represent a subterranean secondary protonema, which plays an important role in the survival and propagation of these mosses, vital especially in the case of the non-sporulating H. xerophilum.     

Protonemal gemmae on Amblystegium serpens (Hedw.) B., S. & G. from Macquarie Island

Abstract

Amblystegium serpens, collected on Macquarie Island, formed protonemal gemmae in laboratory culture. The gemmae germinated to form leafy shoots. They are presumed to be vegetative reproductive structures.     

Spore Germination and Rhizoid Differentiation in Onoclea sensibilis: A Two-Dimensional Electrophoretic Analysis of the Extant Soluble Proteins

Following a geometrically asymmetrical cell division during germination of spores of the fern Onoclea sensibilis L., the small cell differentiates into a rhizoid and the large cell divides to form the protonema. Using silver-staining of two-dimensional gels, we have examined the soluble proteins of spores during germination and of separated rhizoid protoplasts and protonemal cells. Of over 500 polypeptides followed, nearly 25% increased or decreased in prominence during spore germination and the initial phases of rhizoid elongation. Soluble proteins from purified protoplasts of young rhizoids were quantitatively different from those of protonemal cells and germinated spores. Nine polypeptides which appeared after cell division were substantially more prominent in rhizoid protoplasts than in whole germinated spores and have been putatively designated rhizoid-specific polypeptides. The differences in the soluble protein composition of young rhizoids and protonemal cells probably reflect the differential organelle distribution between the two cells as well as differential net protein synthesis in the cytoplasms of the two cells.     

Funaria Rhizoids infected with Pleotrachelus wildermani

Abstract

The recolonisation of bryophytes on soil during 3½ years following fire in a mixed forest in south-west Tasmania is characterised by the presence of Marchantia berteroana, Funaria hygrometrica, Ceratodon purpureus and Polytrichum juniperinum, while limited cover is provided by Campy lop us introjlexus, Tortella calycina and Bryum sauteri. It has been verified that the protonemal growth of the early colonising mosses is more rapid than non-colonising specles. The preference for spores of Funaria hygrometrica, Ceratodon purpureus and Marchantia berteroana to germinate on burnt soil is confirmed. However, it has been shown that burnt substrates do not inhibit the germination of non-colonising species. Therefore, the rapid development of protonemata and gametophytes in the colonising species may be a critical factor for their success.     

The ecology of mosses on a sand dune in Victoria,Australia

Abstract

The ability of eight mosses to with stand the harsh environment of a coastal sand-dune in Victoria (Australia) has been investigated. It is shown that some species are able to re-vegetate areas which have been disturbed by wind, rabbits and vehicles. Their differing performances in relation to growth, rhizoid strength, and withstanding salt spray and sand burial, equip them for different niches. The ratio of dry weights of gametophore/rhizoids is suggested as an indicator of stage of revegetation.     

Notes on the nomenclature of British mosses. I

Abstract

Gemmae found on the protonema of Barbula trifaria are described. The protonemal gemmae of this species and of Gyroweisia tenuis and Eucladium verticillatum, in addition to those recently reported in Schistostega pennata, seem to be adaptations for survival and propagation at low light intensities.