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The vegetative cycle of the foliicolous lichen Phyllophiale, from propagule germination to propagule production, was studied by light microscope observation of thalli colonizing plastic cover slips placed within a lowland tropical forest. Discoid propagules germinated by growth of radially arranged fungal cells and developed directly into lichen thalli. The young lichen comprised a single disc of closely branched, radiating filaments of the algal symbiont Phycopeltis, covered by a network of fungal hyphae extending onto the substrate as a prothallus. The prothallic hyphae incorporated additional Phycopeltis thalli encountered on the substrate. The phycobiont formed a single layer, with individual algal thalli clearly distinguishable within the lichen. Radial growth ceased at points of contact between adjacent phycobiont thalli. The visible shape of the crustose lichen thallus corresponded to the perimeter of the phycobiont thalli within. Propagules were initiated at points corresponding to the margins of the phycobiont thalli, by vertical reorientation of horizontal algal filaments surrounded by fungal hyphae. The lichenized alga produced intercalary gametangia. Degeneration of propagules unsuccessful in lichen establishment sometimes resulted in free growth of the phycobiont. The alga generally maintained its shape, growth pattern, and reproductive independence within the lichen, while also participating in the formation of unique symbiotic propagules.

Cell division, the mating system, and auxosporulation were studied in the marine epipelic diatom Seminavis cf. robusta Danielidis & D. G. Mann. The interphase protoplast contains two girdle-appressed chloroplasts, each with an elongate bar-like pyrenoid, and also a central nucleus, located in a bridge between two vacuoles. Before cell division, the chloroplasts divide transversely and translocate onto the valves. The nucleus relocates to the ventral side for mitosis. After cytokinesis and valve formation, the chloroplasts move back to the girdle, showing a constant clockwise movement relative to the epitheca of the daughter cell. Seminavis cf. robusta is dioecious, and sexual reproduction is possible once cells are less than 50 μm. In crosses of compatible clones, gametangia pair laterally, without the formation of a copulation envelope, and produce two gametes apiece. The intensity of sexualization increases as cells reduce further in size below the 50-μm threshold. At plasmogamy, the gametangia dehisce fully and the gametes, which were morphologically and behaviorally isogamous, fuse in the space between the gametangial thecae. The auxospore forms a transverse and longitudinal perizonium. After expansion is complete, there is an unequal contraction of the protoplast within the perizonium, creating the asymmetrical shape of the vegetative cell. Apart from this last feature, almost all characteristics exhibited by the live cell and auxospores of Seminavis agree with what is found in Navicula sensu stricto, supporting the classification of both in the Naviculaceae. Haploid parthenogenesis and polyploid auxospores were found, lending support to the view that change in ploidy may be a significant mechanism in diatom evolution.

The prothallial development of gametophytes of Olfersia alata and Olfersia cervina (Dryopteridaceae) is described and compared. Spores are monolete, ellipsoid, and with broadly winged perispore. Germination is Vittaria-type and the prothallial development is Aspidium- type. Adult gametophytes are cordiform-spatulate to cordiform-reniform, with marginal and superficial trichomes. Gametangia are of the type commonly found on leptosporangiate homo- sporous ferns. Differences between the two species of genus include size of the spores, width of the perispore, germination time, size of the trichomes, and time of formation of the gametangia. These two species share some features with some species of Arachniodes, Cyrtomium, Dryopte- ris, Phanerophlebia, and Polystichum, such as type of germination and prothallial development and trichomes. They differ from Didymochlaena truncatula, which has prothallial development of the Adiantum-type and lacks trichomes on the sexual phase. The genus Olfersia Raddi (Dryopteridaceae), has two species: Olfersia alata C. Sanchez & Garco´a Caluff and Olfersia cervina (L.) Kunze. Olfersia alata is endemic to Cuba; its main characteristics are all sterile pinnae have decurrent bases, and fertile leaves which are smaller and have fewer pinna pairs than the vegetative leaves. It grows in mountainous mesophytic forests, between 350-400 m (Sanchez et al., 1991). Olfersia cervina is widely distrib- uted in the tropics, from Southern Mexico (Chiapas, Oaxaca, Veracruz), to Southeastern Brazil and the West Indies. In this species the bases of the ster- ile pinnae are not decurrent onto the rachis, and pinnae are short-petiolu- late. It grows between 450-1000 m in damp tropical forests, on rocky and very shady banks (Moran, 1986, 1995; Riba and Perez-Garco´a, 1999). Both taxa are usually terrestrial, rarely hemiepiphytic, with a short trailing rhi- zome. Leaves are markedly dimorphic, sori are exindusiate and linear to ob- long, and spores are monolete, echinulate with a broad perispore. This paper complements existing information about the morphogenesis of the gametophytic phase of dryopteriod ferns and, particulary, focuses on gametophytes of Olfersia. We hope to contribute in this way to the knowledge of the sexual phase of Mexican ferns.

Gametogenesis in male and female gametophytes was studied by light microscopy and EM in the dioecious multinucleate green alga Derbesia tenuissima (Moris & De Notaris) P. Crouan & H. Crouan, where male and female gametes differ in size. Gametogenesis was divided into five stages: 32 h (stage 1), 24 h (stage 2), 16 h (stage 3), 8 h (stage 4), and 0.5 h (stage 5) before gamete release. At stage 1, the first sign of gametogenesis observed was the aggregation of gametophyte protoplasm to form putative gametangia. At stage 2, gametangia were separated from the vegetative protoplasm of gametophytes. Morphological changes of nuclei and organelles occurred at this early stage of male gametogenesis, and organelle DNA degenerated. At stage 3, male organelle DNA had completely degenerated, whereas in female gametangia, organelle DNA continued to exist in both chloroplasts and mitochondria. Gametogenesis was almost completed at stage 4 and fully at stage 5. Small male gametes had a DNA-containing nucleus and a large mitochondrion and one or several degenerated chloroplasts. The mitochondria and plastids were devoid of DNA. The large female gametes had a nucleus and multiple organelles, all of which contained their own DNA. Thus, degeneration of chloroplast DNA along with morphological changes of organelles occurred at male gametogenesis in anisogamous green algae (Bryopsis and D. tenuissima), in contrast with previous studies in isogamous green algae (Chlamydomonas, Acetabularia caliculus, and Diclyosphaeria cavernosa) in which degeneration of chloroplast DNA occurred after zygote formation.

Sporophyte production in Sphagnum was followed annually in 80 permanent 1-m2 plots at the bog expanse of a pristine mire during 1993–1999 and in 60 plots in peat pits abandoned 50 years ago during 1996–1999 in east central Sweden. The nine most abundant Sphagnum species produced sporophytes, with mean annual production ranging from 0.64 to 20 sporophytes/dm2 of cover among species. An estimated mean of 16 million Sphagnum spores/m2 mire area was produced annually at both mires. At the pristine mire, sporophyte production was positively related to the amount of precipitation the previous summer, suggesting that gametangium formation is especially sensitive to summer droughts. At the wetter peat pits, the amount of precipitation during spring in the year of sporophyte formation appeared more important, probably by positively affecting male gamete dispersal and fertilization. Larger patches had a higher probability of producing sporophytes at least once, showing areas with both sexes present among dioecious species, and thus giving an indication of clone size. Only slight differences in sporophyte production were found between the two mires, apart from effects of hydrological conditions and patch size. This indicates numerous colonizations at the peat pits. Summer droughts affected sporophyte maturation negatively by drying out sporophytes prematurely. Spore release phenology differed among species by up to a month and lasted from the beginning of July until the end of August. The early timing of spore dispersal in the most drought-sensitive, lawn-inhabiting sphagna should reduce the risk of sporophytes drying out prematurely during summer droughts.Key words: bryophyte, long-term study, mire, model, sexual reproduction, strategy.

Other than general statements about ‘fruiting’ seasons, published floras provide little or no instructive information on moss phenology. Moreover, detailed primary data on reproductive cycles are limited to a very few mosses and remain unknown for the majority of the commonest species. Thus we recorded, over a three year period, the reproductive stages of five very common mosses ( Bryum capillare, B. radiculosum, Grimmia pulvinata, Schistidium crassipilum and Tortula muralis ) growing on walls in London, England, relying throughout on freshly observed materials rather than dried specimens used in most previous studies. In addition to all the stages visible to the naked eye, which we photographed at regular intervals, specimens were examined microscopically for the presence of viable gametangia, young embryos and the condition of the stomata. Each species had its own distinct phenology and an unique sequence of capsule colour changes. In the two Bryum species, gametangium ontogeny, followed by fertilization, takes place in the spring but the embryos remain dormant until the autumn whereas these stages are autumnal in Grimmia pulvinata, Schistidium crassipilum and Tortula muralis with sporophyte development following immediately. Most stages in sporophyte ontogeny occur over the winter months. The time from embryo formation to spore release ranges from over fifteen months in the two Bryum species down to eight months in Schistidium. In all but this last species there is a delay of up to several months between sporophyte maturation and spore release. In Bryum, hygroscopic movements of the annular cells following heavy rain eventually leads to lid shedding. Over the three years of this study the reproductive cycles were generally the same except that damp weather in the autumn promoted capsule expansion in Grimmia and Schistidium and warm dry weather in the spring hastened capsule maturation in Bryum . Whatever the weather conditions, the stomata of the two Bryum species, Grimmia and Tortula were always open suggesting a primary role in capsule desiccation leading to spore discharge rather than the regulation of gaseous exchange.

While examining specimens of Fissidens Hedw. collected from the Nile Valley, I came across one unusual collection. This voucher, namely IV-B(8), was collected by Refai in 1986 and labelled as Fissi...

Specimens of Fallacia tenera were collected from the surface sediment at in a river estuary in Japan. Auxosporulation occurred in a rough culture. Morphological structures of vegetative cells and auxospores were observed in detail. The vegetative cells have one H-shaped chloroplast. The striae were interrupted by two depressed lateral sterna internally and partly covered by a finely porous conopeum on the external surface. The lateral sterna and porous conopea formed two more or less curved longitudinal canals connecting with the exterior via opening pores on both sides of a terminal fissure. This combination of characteristics is unique to the genus Fallacia. The cingulum was composed of three bands, such as an open valvocupula and two comparatively thin pleurae. The two pleurae could be distinguished by the shape of their ligulae. The second band had a triangular ligula, whereas the ligula of the third band is arc-shaped. The auxosporulation was type IA1a in Geitler’s classification. Two paired gametangia formed two anisogametes in each of them. Two auxospores formed in the thecae of the gametangia after a trans physiological anisogamy. The perizonium of the auxospore consisted of a set of transverse bands and five longitudinal bands. The primary transverse band was about twice wider than the secondary ones. The circular incunabular scales were present on the two terminals of the auxospore and on the surface of the primary transverse band. The primary longitudinal band had an acute terminal and was flanked by secondary longitudinal bands. Each side had two secondary longitudinal bands. All longitudinal bands were immediately beneath the transverse bands. Morphological comparison between Fallacia and Pseudofallaica, and the taxonomic position of F. tenera is also discussed.

The reproductive biology of three sympatric species of Dicranoloma Ren. was investigated: D. billardierei (Brid. ex anon) Paris, D. menziesii (Taylor) Renauld, and D. platycaulon Dixon. The developmental stages of gametangia and sporophytes were identified for each species and a maturity index value assigned. Although archegonia were initiated after antheridia, archegonia matured within two months while antheridia took five to six months to reach maturity. Antheridia were initiated during winter and archegonia in spring in D. menziesii and D. platycaulon. In contrast, antheridia were initiated during late spring-summer and archegonia in autumn in D. billardierei. Fertilization occurred in late summer in D. menziesii, mid autumn in D. platycaulon, and early winter in D. billardierei. An overlap in sporophyte generations occurred in D. billardierei and D. platycaulon. Maturation of the sporophyte took 18–24 months in these species, whereas sporophytes of D. menziesii matured within 12 months.

Eighteen collections of red-coloured Audouinella from Central Mexico and southeastern Brazil detected three species. The most common species, A. eugenea, is characterized by macroscopic thalli, the erect system consisting of filaments with cylindrical cells, undifferentiated into proximal and distal parts, and relatively large monosporangia (≥12.0 µm long). Spermatangia and possible propagules were observed in some Mexican populations. This is the third Audouinella species observed to have gametangia and the first member of the Acrochaetiales with putative propagules. The second species, from Central Mexico, was characterized by the following features : macroscopic thalli, the erect system differentiated into proximal parts with cylindrical cells, unbranched or rarely branched, and distal parts with barrel-shaped cells, abundantly branched to form dense fascicles, with alternate or dichotomous branching, some at right-angles to the axis, and relatively large monosporangia (≥12.0 µm long). The morphologica...

Sematophyllum subpinnatum (Brid.) E.Britton is an autoicous species of moss with a pantropical distribution. Two populations of S. subpinnatum from a Tropical Lowland Forest remnant were sampled monthly over a period of 2 years. The results were similar in the two populations. The average number of antheridia produced per perigonium ranged from eight to 20, and of archegonia per perichaetium from three to 26. Antheridial and archegonial initiation, maturation and fertilized archegonia occur throughout the year, but increased in frequency during the rainy season. The initial stages of sporophyte development were most common between the months of June and September, indicating that, although S. subpinnatum produces gametangia all year round, the rainy season is the most favourable period for fertilization.

Recent field-based studies in the Bryopsidales have provided a wealth of reproductive information for several ecologically dominant genera, yet inconspicuous members of the order often remain poorly described. Here we report reproductive events for aquarium-grown populations of Rhipidosiphon javensis and provide statistical size ranges for vegetative and reproductive features for the first time. Hawaiian representatives of the genus develop gametangia over a three-day period, and follow the typical reproductive pattern found in other members of the suborder Halimedineae, being holocarpic and releasing gametes in predawn hours.

The present paper reports on the study of French and Danish strains of Acinetospora crinita (Harvey) Kornmann and their responses in growth and reproduction to various combinations of temperature and salinity. The distribution of the species in both hemispheres may be explained by the temperature requirements for growth and reproduction. The limit at lower latitudes in both hemispheres is a lethal limit, at higher latitudes it is probably a growth and reproduction limit. Acinetospora crinita is a stenohaline species and only occurs in high salinity areas in Danish waters. This paper also discusses the status of the genus Acinetospora, which has been considered to be a phase in the life history of some Feldmannia and Hincksia species. We conclude that there are several characters that justify independent status at the genus and species level. The large variation in reproductive patterns is enigmatic and adds to the taxonomic confusion. In A. crinita various reproductive structures occur: megasporangia/acinetosporangia, unilocular sporangia (some are apomeiotic), monosporangia, plurilocular sporangia which are presured to be gametangia, and a strain is known from the United States with reproduction solely by fragmentation. The combination of reproductive structures appears to be unique to specific strains.

Water motion did not inhibit gamete release in cultures of the coenocytic green alga Bryopsis plumosa (Hudson) C. Agardh; however, the number of gametangia that released gametes increased significantly under transiently calm conditions. This stimulatory effect of calm conditions in the laboratory was found in isolates from two different areas of the Maine coast. The isolates were all monoecious, but strong differences in levels of fertilization, numbers of male and female gametes remaining following fertilization, and levels of polygamy (=zygotes formed by fusions of more than two gametes) were observed among isolates. These data support the hypothesis that organisms with external fertilization are able to sense and respond to water motion in ways that favor reproductive success.

The allogamous raphid diatom Achnanthes longipes C. A. Agardh possesses a complex breeding system involving interactions between three types of clone: monoecious, unisexual and bisexual. Previous studies showed that these three types can be crossed with each other, with a tendency for sexual characteristics to be inherited: inbred monoecious lineages gave rise to monoecious or, very rarely, to bisexual clones, while inbred unisexual lineages yielded unisexual and bisexual clones. The current paper reports on the progeny of crosses between monoecious and unisexual clones and their inbred offspring. All three types of clone appeared in the F1 and F2, although unisexual clones of opposite sex to the parental clone were not found. Inbreeding depression was observed and also a tendency for ‘normal’ auxosporulation (producing two auxospores per pair of gametangia) to be replaced by ‘reduced’ or ‘intermediate’ auxosporulation (producing one auxospore per pair). In addition, patterns of incompatibility were obser...

Mature, gametangia-bearing photosynthetic gametophytes of Phylloglossum can be grown from the nonphotosynthetic, cylindrical, negatively gravitropic immature stages in illuminated axenic culture on a nutrient medium with or without 0.2% glucose. The gametangial-bearing region of these gametophytes, the photosynthetic crown, grows horizontally from the apex of the immature cylindrical stage. At maturity the photosynthetic crown is thickened and bilaterally symmetrical. It is usually narrow and bean-shaped with dorsal and ventral regions. Occasionally, the ventral region becomes thicker and the crown is deltoid in cross section. The dorsal edge or ridge of the crown is the gametangial region with archegonia and antheridia. The gametangia are often hidden because they are interspersed among numerous uni- or bicellular paraphyses. The lateral surfaces below the gametangial region lack outgrowths, and the ventral region is covered with long rhizoids. The apical meristem at the anterior end of the crown is overarched by the developing dorsal tissue of the gametangial ridge. The lower derivatives of the meristem form the ventral region with rhizoids. Phylloglossum gametophytes are unusual because their mode of organic nutrition changes from mycorrhizal to photosynthetic during ontogeny.

Two species of the genus Vaucheria, V. lii Rieth and V. racemosa (Vaucher) DC., are reported from Connecticut and New England for the first time. Despite sampling over 150 freshwater habitats in Connecticut, each species has been located only at a single site. Culture conditions in the laboratory stimulated growth and, after extended periods of time, the production of gametangia allow- ing for the identification of each species. Despite its worldwide distribution, V. lii is shown to be a rarely collected species throughout its range.

Gametangial distribution patterns on gametophores of Physcomitrella (Aphanoregma) patens were studied. Plants were grown axenically under controlled laboratory conditions. Some gametophores produced clusters of archegonia at their apices or in the axils of their uppermost leaves. Of these gametophores, some possessed a few antheridia located at the periphery of the archegonial clusters. Other gametophores produced apical and axillary antheridial clusters unadulterated by archegonia. Thus, this P. patens isolate, ‘maintained in culture since 1962, is paroicous or autoicous depending upon which gametophores are considered. Typically, filiform paraphyses were associated with archegonial clusters and clavate paraphyses with antheridial clusters. Archegonia, solitary or in clusters, also developed from internodal surface cells of the gametophores. Such ectopic archegonia had no associated paraphyses. Many immature sporophytic stages were noticed within archegonia but their development into mature sporo...

The present paper deals with growth and attachment of isolated utricles from various parts of thalli in Codium fragile (Suringar) Hariot, with utricles from different stages being studied in laboratory culture in order to select suitable utricles for conducting assays on seaweed attachment. Clavate utricles were observed in the thalli at three stages: utricles without a gametangium, those with a gametangium before and after gamete release, and slender utricles without a gametangium. The clavate utricles were abundant except for the basal parts of the thalli, so that these utricles were used in the present study. The utricles isolated from six parts of the thalli and those at three different stages had the ability to form medullary filaments and attach to the substratum by their elongated filaments. However, the ability of the isolated utricles to elongate their filaments differed among the parts of the thalli used for isolating the utricles, and the ability of the utricles to form and elongate their filaments differed among the stages of the utricles. Furthermore, utricles with a gametangium were obtained only in a certain period when the thalli were fertile. Therefore, the clavate utricles without a gametangium isolated from the higher orders of axes are more suitable for use in assays on seaweed attachment.

Sexual reproduction in the domoic acid–producing pennate diatom Pseudo-nitzschia multiseries (Hasle) Hasle is dioecious and involves pairing of two morphologically isogamous parent cells (gametangia) and the production of two gametes per gametangium. Gamete fusion leads to the formation of zygotes, which elongate into auxospores. Within each auxospore, a long initial cell is formed, thereby restoring the longer cell sizes in the population. Mating experiments were performed by mixing active “male” and passive “female” cells from pairs of clones and growing them under different light : dark (L : D) cycle regimes. Two pairs of clones were studied: one pair was ontogenetically older and therefore shorter than the other. After mating, the relative abundance of gametes, zygotes, auxospores, and initial cells was determined for a minimum of four consecutive days. Cell size, which reflects population age, influences sexualization. The short-celled clones had a lower maximum proportion of gametes per vegetative cell (4%) than the long-celled clones (49%), suggesting that the former were nearing the minimal cell length capable of sexualization. The size range within which P. multiseries is able to reproduce sexually is 23–70% of the maximum cell length. A positive correlation was found between hours of light exposure per 24 h at approximately 100 μmol photons m⁻² s⁻¹ and sexual cell production of the ontogenetically younger clones. Greatest production of initial cells per female gamete (26%) occurred in 10 h of light. Results from this study indicate that the most biologically successful light regimen in culture corresponds in nature to the day length of the fall bloom from which these clones were isolated.

Two combinations of features exist in species of the Pseudobryopsis/Trichosolen complex (Bryopsidales, Chlorophyta): (1) gametangia are separated from the supporting branch by a plug and are emptie...

Male and female gametes were formed within the same gametangiurn on reproductive plants of Codium fragile (Sur.) Hariot ssp. tomentosoides (Van Goor) Silva growing off Appledore Island in the Gulf of Maine, USA. The female gametes were approximately twice the diameter of male gametes and outnumbered male gametes in the same gametangium by approximately six times. Fusion appears to require gametes from different gametangia if not different plants.

This paper continues a series of studies of the allogamous raphid diatom Achnanthes longipes, which has a complex reproductive system combining unisexual, bisexual and monoecious behaviour. Following earlier work on the effects of inbreeding in the progeny of crosses between two unisexual clones, we studied the progeny of clones that are capable of a high degree of selfing in monoclonal culture (‘monoecious clones’). Three generations of selfed progeny were examined. In addition, we investigated the F1 generation obtained after crossing two different monoecious clones. Monoecious clones produced monoecious or, more rarely, bisexual progeny, but did not give rise to unisexual progeny. As in inbred lineages made by crossing closely related unisexual clones, inbreeding in monoecious lineages leads to a reduction in the number of gametes formed by the gametangia, from two to one. Inbred clones exhibit marked inbreeding depression and only three inbred generations were possible in monoecious lineages. In the t...

Microspectrophotometry with the DNA-localizing fluorochrome 4′,6-diamidino-2-phenylindole (DAPI) was used to estimate nuclear genome sizes in 12 species representing two families of the Dasycladales. Estimated 2C DNA contents in these taxa range from 0.7–1.4 pg in the family Dasycladaceae and from 0.9–2.4 pg in the family Acetabulariaceae. In both families, species exhibiting characteristics considered to be primitive appear to have 2C DNA contents that approximate 50% of values found in species exhibiting characteristics considered to be more advanced. Results suggest that polyploidy events have accompanied evolution in the order but apparently have been infrequent and conservatively preserved, leading to a narrow range of relatively small genome sizes. Limitations on genome size increase are discussed in terms of constraints imposed by a prolonged uninucleate stage. Interspecific comparisons of genome size and gametangium volume suggest an inverse relationship. Gametangium volume appears to hav...

Oedogonium pluviale Nordstedt is nannandrous, described as possessing single-celled dwarf males. In some studies the dwarf males appear to have a reduced, lens-shaped pedicular portion whose nature and structure remain unclear. The present study aims to: 1) establish whether dwarf males of O. pluviale are single- or two-celled, 2) describe the different developmental stages of dwarf males, and 3) understand the nature of the pedicular portion. Mitotic division of the dwarf male was observed, but neither upwards phycoplast migration nor synthesis of a gametangial cell wall occurred. Instead, the phycoplast and cell plate migrated downwards, producing a small pedicular portion whose content then degenerated. The antheridium occupied most of the dwarf male wall. Gametogenesis thus took place inside the wall of the young dwarf male (internal gametangium). Because the pedicular cell degenerated, we define this type of dwarf male as pseudo-single-celled to differentiate it from a true single-celled dwarf male. The antheridial nucleus underwent one mitotic division to give rise to two gametes. Instead of a true wall between gametes, mucilage condensed and was observed as a discrete layer that disappeared during gamete release.

During the induction of gamete-producing gametangia, induced gametophytes were collected at 4 days intervals (0,4,8,12 d) and total RNAs were isolated by CsCl gradient ultracentrifugation. Some stage-specific expressed mRNAs were identified by differential display of mRNAs from different developing stages of the gametophytes. The cDNA of one specific mRNA was verified, cloned and sequenced. This gene was specifically expressed during 4 days of induction, and had partial homologous sequence with tobacco IAA-binding protein gene. It suggests that this cDNA may represent a gene which is related to the IAA regulating function during the development of the gametophytes.

Shoots of Dicranum majus were collected monthly during the snow-free period from permanent plots to study the reproductive phenology in a boreal spruce forest in central Norway. Numbers of sporophytes (current and previous years), gametangia and dwarf males on each shoot and the reproductive stage of gametangia and sporophytes were registered. Gametangia are formed either in late autumn or in early spring, fertilization occurs in June and July and spores are dispersed during August to October in the following year.Mature archegonia were present only during a restricted period (June-July) while mature antheridia were found throughout the summer and autumn.Dwarf males were found only in a region about one cm below the apex. There was no trace of old male gametophores below, indicating that gametophores are annual. However, from this study it is not possible to conclude whether the gametophyte is annual or new males are formed through, for instance, perennial protonema.Fertilization frequency in the ...

Gametogenesis in Atractomorpha porcata Hoffman was initiated b the synchronous mitotic division of nuclei within a multinucleate gametangium. Uninucleate gametes were subsequently produced following two series of cytokinetic divisions. The first series involved the formation of phycoplast microtubules (phycoplastic cytokinesis), whereas the second series did not (nonphycoplastic cytokinesis). Centrioles were connected by a rudimentary striated distal fiber by the time they migrated to the planes of division preceding the first series of cytokinetic division. These first divisions produced binucleate gametocytes. A well-developed flagellar apparatus lay near the cell surface in close proximity to each nucleus of the gametocyte prior to the second series of cytokinetic divisions that produced the uninucleate gametes. As seen in apical view, the paired basal bodies were directly opposed, with no lateral displacement of their longitudinal axes. In lateral view, the paired basal bodies diverged from one another at an angle of 130–180° (female) or 170–180° (male) and were connected by an arched, distal striated fiber about 670–750 nm long and 600 nm at its widest part. Four electron-opaque, pyramid-shaped lateral bodies flanked the basal bodies in close contact with their undersurfaces. The flagellar roots demonstrated a cruciate arrangement, with s = 6–9 over 1 (female gametes) or 7–10 over 1 (male gametes) microtubules and d= 2 microtubules. In male gametes, one of the multistranded roots was located close to the eyespot, and a second system of cytoskeletal microtubules was detected internally. Based on gamete ultrastructure, Atractomorpha porcata appears to be the most undifferentiated member of the genus.

The morphology of gametangia was examined in 43 pairs of isolates (mating types A1‹A2; 11 A1 and 24 A2 isolates; five isozyme}electrophoretic types) of Phytophthora cinnamomi. An amphigynous antheridium always formed with each oogonium. However, in 41 of the crosses a proportion (39 had 0‐2‐10% and two had " 30%) of oogonia also consistently had single or multiple paragynous antheridia. Single or multiple paragynous antheridia formed concurrently with amphigynous ones during the period of gametangial production in paired colonies. Where there were multiple paragynous antheridia associated with an oogonium, sometimes additional antheridia formed after fertilization or even after oospores were visible. Developmental studies showed that when meiosis in amphigynous and paragynous antheridia was simultaneous, fertilization tubes developed synchronously from both. However, cytological examination indicated that either a nucleus from an amphigynous or a paragynous antheridium fertilized the oosphere. Observations of paragynous and amphigynous, and amphigynous-only associations suggested that fertilization from either type of antheridium only occurred when meiosis in the oogonium was nearly synchronous with that of the antheridium. Asynchronous meiosis between oogonia and antheridia may contribute to failed fertilization and aborted oospore development. This appears to be the first description of paragynous antheridia in P. cinnamomi and the second observation of oogonia with both paragynous and amphigynous antheridia in a heterothallic Phytophthora species. Moreover, the development of both paragynous and amphigynous antheridia with an oogonium is rare in Phytophthora, as is the development of multiple antheridia. Antheridial variation is a characteristic to be taken into account in isolate identification. Nuclei from paragynous antheridia appear able to fertilize oospheres and therefore, have a role in sexual reproduction.

The reproductive strategy of a marine alga with a heteromorphic biphasic life cycle was studied by analyzing various sexual reproductive characters in light of the evolution of anisogamy. Gametophytes of Monostroma angicava were dioecious and their gametes were slightly anisogamous. Volume of gametangium, density of gametangia and area of mature gametangial parts on each gametophyte did not differ from male to female. Therefore, the reproductive biomass investment for gamete production was considered to be the same for each sex. Anisogamy in this alga appeared to be derived from the difference in the number of cell divisions during gametogenesis, because the majority of male gametangia each produced 64 (26) gametes and the female produced 32 (25) gametes. This corresponded with measurements of cell size in male and female gametes. Further, the sex ratio was 1:1 for sexually mature plants sampled at Charatsunai. Therefore, it was suggested that in the field twice as many male gametes are released as female gametes. Liberated gametes of both sexes showed positive phototaxis. The swimming velocity of freshly liberated male gametes was a little higher than that of female gametes. Male gametes had the potential to swim for ca. 72 h and female gametes for ca. 84 h. The difference in gamete motility between the two sexes seemed to be related to cell size. Planozygotes were negatively phototactic and swam more rapidly than gametes of either sex.

Examination of type material, comparative studies on vegetative characters and data from published accounts of sporangia, gametangia and spermatozoids are used here to further develop and strengthen generic and species concepts in Zonaria and Homoeostrichus. Zonaria is characterized by octosporangia which lack a stalk cell and occur among whitish paraphyses, by the presence of cortical cells in indusiate sporangial and oogonial sori, and by slightly elongate sterile cells bordering the antheridial sori. Other characters (mucilage in sporangial and oogonial sori, biflagellate sperm with a row of many tall spines along the anterior flagellum) may also be diagnostic of Zonaria but have not been demonstrated in the generitype. Eight species are retained in Zonaria. Generic placement of Zonaria stipitata, described on vegetative characters, requires confirmation. Homoeostrichus, as typified by Homoeostrichus sinclairii, is defined by the presence of brown paraphyses in nonindusiate sporangial and oogonial sori...

Regeneration from Platycerium bifurcatum scales in vitro was observed for the first time. Regeneration was obtained from scales detached from in vitro grown juvenile shoots. Regeneration began as rhizoids or as a proliferation of one or more scale cells into undifferentiated outgrowths distinguishable from adjacent cells by their shape and colour. Outgrowths developed into adventitious buds, aposporous gametophytes, or remained undifferentiated. Numerous outgrowths formed rhizoids on their surfaces. Aposporous gametophytes produced gametangia. Sucrose enhanced scale viability and regeneration, and promoted rhizoid development on outgrowths, but sucrose concentrations greater than 0.1% tended to inhibit apospory.

Monoecious, bisexual and unisexual clones of Achnanthes longipes were isolated from the Black Sea and studied in laboratory culture. Clones differed in their growth characteristics : in monoecious clones the cells formed tufted aggregations while in other clones they were more dispersed. Bisexual and unisexual clones exhibited intraclonal (monoecious) reproduction, but only at a very low frequency and usually within a more restricted size range than in monoecious clones. Interclonal crosses were made in all possible pairwise combinations. Abundant auxosporulation took place in all crosses, except where unisexual clones of the same sex were incubated together. Auxosporulation was more vigorous and occurred over a wider size range in interclonal crosses than during monoecious reproduction. Sexual reproduction is isogamous. In the commonest pattern of auxosporulation, two paired gametangia each produce two gametes, which fuse to give two auxospores. More rarely (9% of pairs), the gametangia produce only one ...

Mating interactions in Phytophthora infestans, a heterothallic oomycete, are regulated by sexual compatibility loci and a system of sexual preference. The development of gametangial associations in this species were examined using matings between strains containing a β-glucuronidase (GUS) transgene and nontransformed strains. The GUS gene enabled the facile assessment of whether oospores resulted from hybridization between isolates or from self-interactions and allowed measurements of the sexual preference of strains. Depending on the strains being mated, from 5 to 99% of the total oospores formed resulted from outcrossing. In such hybrid pairings, A1 and A2 field isolates generally acted as predominant females and males, respectively. Nevertheless, genetic analyses indicated that sexual preference and compatibility type were determined by unlinked loci. The sexual preference of most strains varied depending on the relative preference of their mating partners. Both sexual preference and the frequency of outcrossing versus self-interactions varied with the position of gametangia within the mating culture.

A comparative study of fertile sporophytes has been carried out on seven dictyotalean species from Australia. Patterns of sporangial distribution and development are similar in Zonaria angustata, Zonaria diesingiana, Zonaria spiralis, Zonaria turneriana and Lobophora variegata but they differ in Homoeostrichus olsenii and Homoeostrichus sinclairii. In Zonaria and Lobophora, sporangia occur in indusiate sori, are embedded in a mucilaginous matrix and, in Z. diesingiana, Z. spiralis and Z. turneriana, are surrounded by whitish paraphyses. In contrast to Zonaria, the indusiate sporangial sori of H. olsenii form adjacent to concentric rows of brown paraphyses but they lack both mucilage and paraphyses. Sporangia of H. sinclairii occur among dense brown paraphyses which cover the terminal thallus segments. Sporogenesis in species of Zonaria and Lobophora differs conspicuously from other Dictyotalean genera in that nuclear divisions occur when the developing sporangium is quite small, a sporangial stalk cell is...

SUMMARY Gamete discharge by the coenocytic green alga Bryopsis plumosa (Hudson) C. Agardh is induced by light. The mature male gametangia consist of a mass of quiescent male gametes and a large central vacuole. Within a few minutes after the onset of irradiation, breakdown of the tonoplast of the central vacuole and initiation of gamete motility occur simultaneously. This is followed by a forced discharge of moving gametes through a hole ruptured at the subapical region of the gametangium. The action spectrum for the light-induced gamete discharge was determined from a series of fluence-response curves. This action spectrum, having two major maxima at 370 and 450 nm, indicates the involvement of a blue light/UV-A-absorbing photoreceptor previously described as ‘cryptochrome’.

Blade cells of Ulva mutabilis Foyn (Chlorophyta) excrete regulatory factors into their cell walls and into the environment. These factors are essential for the maintenance of the vegetative state. “Sporulation inhibitor-1a” (SI-1a) is a glycoprotein that was isolated from the culture medium of axenic Ulva growing as an undifferentiated callus. This protein was unusually stable to denaturing treatments and showed an extremely high apparent molecular mass (Mr) of 1–4 × 107 daltons estimated by size exclusion chromatography. The glycosylation was not essential for activity. SI-1a suppressed gametogenesis completely at concentrations lower than 10−14 M. When Ulva developed normally in the presence of their symbiotic bacteria, smaller forms of SI-1 accumulated in the medium (104–106 daltons). Sporulation inhibitors of the same size spectrum and with similar properties were also extracted from crude cell walls of nonaxenic Ulva. A class of different nonprotein sporulation inhibitors (SI-2) of very low Mr and yet unknown structure was isolated from the inner space between the two blade cell layers. Excretion of all SI-1 forms decreased with maturation of the thallus, whereas the overall concentration of SI-2 in the thallus stayed constant throughout the life cycle. The SI-2 affected different Ulva species whereas SI-1 was species-specific. Gametogenesis was induced upon removal of both Sporulation inhibitors from small single-layered fragments of mature blades. After a “determination phase” of 23–46 h, dependent on the time of induction within the cell cycle, the cells became irreversibly committed to differentiation and were no longer susceptible to SI-1 or SI-2. Subsequently, during a 28-h “differentiation phase,” 16 progametes were formed by synchronous genome doublings and cell divisions and differentiated into mature gametes. These became motile and were released from the gametangia when the concentration of a “swarming inhibitor” of low Mr, excreted mainly during the “determination phase,” declined below a threshold concentration. The biochemical properties of these regulatory factors and their effects on gametogenesis and gamete release are described.

The sexual development of the fungus Phycomyces is inhibited by light. The action spectra for this photoinhibitory effect were determined for 48 h continuous exposure between 350 and 700 nm wavelengths during the mating process. Effective wavelengths were shorter than 490 nm, but the most effective wavelengths depended on the stage of sexual development. In early stages of progametangium formation, the major peaks appeared near 360 nm with small shoulders at 410 nm, but in later stages, after gametangium formation, only single peaks were detected in the UVA range (350–390 nm). Low-fluence irradiation in the later stage, however, revealed inhibitory effectiveness at 370–410 nm, implying the existence of a dual photoresponse and multiple regulatiory systems in the mating process of Phycomyces.

We present the first experimental results on salinity tolerance and regulation mechanisms in the genus Tolypella. The two species investigated, T. nidifica and T. glomerata, regulate turgor pressure with almost complete effectiveness by adjustment of K + and Cl - concentrations. Sucrose is also involved. The mechanism is basically identical to the mechanism of turgor pressure regulation previously identified in representatives of the genera Chara and Lamprothamnium. Since Chara and Lamprothamnium on the one hand and Tolypella on the other belong to different phylogenetic branches that separated early in the geological history of the Characeae, the K + regulation mechanism can be assumed to represent an ancient pattern derived from a salt-tolerant common ancestor. Furthermore, our experiments provide evidence that salinity is a limiting factor for fertility in both T. nidifica and T. glomerata. Although the onset of gametangia covers the whole range of salinities tested here (0-29 psu), 12 psu was the inhibitory level for the formation of mature oospores. Fertilization is probably disturbed by an increase in salinity. An inability to reproduce sexually under euryhaline conditions could explain why the distribution of the two species is restricted to oligo- and mesohaline environments, despite the wide range of salinity tolerance of their vegetative apparatus.

SUMMARY Morphology of field material and life history in culture were studied in Scytosiphon canaliculatus (Setchell et Gardner) comb. nov. from northern Japan. Erect gametophytes of S. canaliculatus are cylindrical, tubular, up to 7 mm wide and 40 cm long, and without regular constrictions. S. canaliculatus has pronounced anisogamy and ascocysts accompanied with plurilocular gametangia. The life history of S. canaliculatus showed an alternation between erect gametophytes and crustose prostrate sporophytes bearing unilocular sporangia. Since field sporophytes of S. canaliculatus were found to be identical with Hapterophycus canaliculatus Setchell et Gardner (Ralfsiaceae, Phaeophyceae), it is proposed to transfer H. canaliculatus to the genus Scytosiphon. In the field, gametophytes with plurilocular gametangia appeared in spring and disappeared in summer. Sporophytes with unilocular sporangia were collected in late autumn and winter. Unilocular sporangia were produced at 15°C in short-day culture conditions and unispores developed into erect gametophytes at 5–15°C. It is suggested that the seasonal Occurrence of gametophytes in the field is due to the seasonal formation of unilocular sporangia, which is regulated by temperature and photoperiod.

SUMMARY The life history of Cladophora surera sp. Nov., described from the south of the province of Buenos Aires, Argentina, was found to be diplobiontic and isomorphic with haploid gametophytic (n= 24) and sporophytic (2n= 48) plants. Other freshwater species, namely C, suhriana Kutz, and C. callicoma Kutz. have also been reported to be diplobiontic and isomorphic but differing from C. surera by their ploidy level. Plants exhibit great morphological variation, as the number of branches/mm2 tends to increase with higher water velocity, thus adopting morphotypes that resemble very different species, that is, C. vagabunda (L.) Hoek, C. glomerata (L.) Kutz., C, laetevirens (Dillw.) Kutz., C. brasiliana Martens, C. dalmatica Kutz., C. vadorum (Aresch.) Kutz. and C. rivularis (L.) Hoek., but clearly differing from them by other morphological parameters; apical cell diameters, The ploidy level 24/48 has not been established for a species of Cladophora. Autogamy is the normal conjugation method and can take place even inside the gametangia before the gametes are released. Isogametes conjugate in a slow behavioral anisogamy, in which the contents of one migrate to the other. Tetra-flagellate zoospores result from meiosis.

Branching of the stalk of Acetabularia acetabulum L. (Silva) was investigated by inbreeding and by a brief treatment of gametangia with a variety of antibiotics. The position of the branch along the stalk varied, implying that branching was not restricted to any one time in development (base is oldest and apex is youngest). The branching phenotype was not inherited in Mendelian fashion. Although three microscopic structures (“bubbles,”“pustules,” and “scars”) occurred on the stalks of cells that had branched, these structures were not statistically correlated with branching in the population (n=699 cells). However, brief treatment of gametangia with a new antibiotic mixture did eliminate all macro- and microscopic structures associated with branching of the stalk in the subsequent generation. We could not fulfill Koch's postulates or provide clear evidence for the pathogenic nature of cell branching. Our brief antibiotic treatment of gametangaa of Acetabularia acetabulum was rapid, had no adverse effects, and virtually eliminated branching (and any potential pathogens) from laboratory cultures in the subsequent generations. Our method allows biochemical and molecular analyses to proceed uncomplicated by the possible presence of other organisms and provides a clean baseline for the future selection of mutations that may induce heritable branching.

SUMMARY The vegetative morphology and life history of Halopteris filicina (Grateloup) Kutzing, collected from Korea, were examined in laboratory culture. Field plants attaining 3–5 cm in height were epilithic, tufted, yellowish-brown, and produced numerous erect axes with alternately distichous branches from compact basal discs. They were cultured under a 12:12 h LD photoperiod at 10°-C, 15°C and 20°C to observe the influence of temperature on reproduction. At 10°C plants grew only vegetatively, whereas at 15°C and 20°C they produced unilocular sporangia. Unispores released from sporangia developed into monoecious, anisogamous gametophytes that formed plurilocular female and male gametangia on the same lateral branches. The zygotes, by fusion of female macrogametes and male microgametes, developed into sporophytes bearing unilocular sporangia, whereas the unfused female gametes germinated parthenogenetically. This species was confirmed to have an isomorphic life history, basically similar to the other species of Sphacelariales.

The life history, reproduction and development of Desmarestia menziesii J. Agardh from Antarctica is described. Unilocular sporangia occur singly or in small groups in the outermost cortical layer of the sporophyte. They are formed by periclinal division of cortex cells into a stalk cell and the sporangium initial. Meiospores germinate into dioecious microscopic filamentous gametophytes. As in other perennial Antarctic species of the Desmarestiales, gametangia are formed in culture under short-day conditions or in darkness. In nature, juvenile sporophytes should therefore be formed in winter. They develop only attached to the oogonium. At first they are uniseriate and elongate by means of an intercalary meristem located in their middle part. Laterals are formed predominantly in this region, and they subsequently give rise to secondary laterals. The branching pattern is opposite to alternate in both young and adult plants. Cortication of the main axis is initiated by filaments growing out from the lowermost cells of the primary laterals. In sporophytes of this developmental stage the meristem of the main axis is confined to a small region where cortication starts and above. Lateral branches elongate and become corticated in the same way as the main axis. In mature plants, cells of the inner cortex can become meristematic again and form a meristoderm which contributes to axis thickness by periclinal and anticlinal divisions. The observations are discussed in relation to possible evolutionary relationships in the genus Desmarestia and in the order Desmarestiales.

Zygorhizidium planktonicum (Chytridiales) an obligate, epibiotic parasite of freshwater diatoms was recently isolated from Lake Lanier, Georgia. Host specificity and ultrastructural morphology of clones infecting Synedra acus were investigated to further evaluate the life history and taxonomic significance of host-specific strains. Host range studies revealed that germination and sporangium development were con- fined to Synedra sp., S. acus, and S. ulna. On occasion, zoospores loosely adhered to Asterionellaformosa; how? ever, subsequent growth did not ensue despite efforts to induce parasitism in mixed cultures and altered environmental conditions. Ultrastructural studies of conjugating gametangia demonstrated the fusion of thalli by means of a narrow, smooth-walled tube and the apparent migration of the nucleus and other or- ganelles from the donor gametangium to the larger, recipient thallus. The resulting resting spore possessed a thick multilayered wall, either one or two nuclei, and electron opaque bodies of unknown composition. Zoospores contained discrete morphological features including a rumposome-associated fibrillar vesicle, dis- persed ribosomes, and a dense particulate body. Our findings regarding this disjunct population confirm the occurrence of host-specific variants in Z. plankton? icum. Host selection indicates a conserved ontogeny which further suggests that host-selective strains have coevolved with their respective diatom hosts.

Sexual reproduction and protoplast structure are used to check the classification of the naviculoid genus Placoneis Mereschkowsky (Bacillariophyta). The gametangia are closely associated within a robust mucilage capsule throughout auxosporulation, and pairing is ± random with respect to asymmetries of the frustule and protoplast. Two gametes are produced per gametangium, which are morphologically identical but differentiated into active and passive (physiological anisogamy). The supernumerary nuclei from meiosis II begin to degenerate soon after telophase II, but can still be detected in the initial cells. The gametes become rearranged within the gametangia after meiosis II and plasmogamy takes place via a single, simple aperture. The auxospores expand parallel to the apical axes of the gametangia. The classification of Placoneis in the Cymbellales, as the sister group to the cymbelloid and gomphonemoid diatoms, is supported by valve and protoplast structure, the method ofchloroplast division, an...

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:43:15Z No. of bitstreams: 1 S1676-06032012000200019.pdf: 520469 bytes, checksum: 5fc34f8688f77bf3d4b5a437fc567902 (MD5) Made available in DSpace on 2013-08-22T18:43:15Z (GMT). No. of bitstreams: 1 S1676-06032012000200019.pdf: 520469 bytes, checksum: 5fc34f8688f77bf3d4b5a437fc567902 (MD5) Previous issue date: 2012-06-01 Made available in DSpace on 2013-09-30T19:30:51Z (GMT). No. of bitstreams: 2 S1676-06032012000200019.pdf: 520469 bytes, checksum: 5fc34f8688f77bf3d4b5a437fc567902 (MD5) S1676-06032012000200019.pdf.txt: 36829 bytes, checksum: d90ecb19cc0ed10eac7442bc64e39e0b (MD5) Previous issue date: 2012-06-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:08:28Z No. of bitstreams: 2 S1676-06032012000200019.pdf: 520469 bytes, checksum: 5fc34f8688f77bf3d4b5a437fc567902 (MD5) S1676-06032012000200019.pdf.txt: 36829 bytes, checksum: d90ecb19cc0ed10eac7442bc64e39e0b (MD5) Made available in DSpace on 2014-05-20T15:08:28Z (GMT). No. of bitstreams: 2 S1676-06032012000200019.pdf: 520469 bytes, checksum: 5fc34f8688f77bf3d4b5a437fc567902 (MD5) S1676-06032012000200019.pdf.txt: 36829 bytes, checksum: d90ecb19cc0ed10eac7442bc64e39e0b (MD5) Previous issue date: 2012-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) (O gênero Vaucheria D.C. [Vaucheriaceae, Xanthophyceae] no Sul do Brasil: aspectos taxonômicos e ecológicos). O levantamento taxonômico e ocorrência ambiental do gênero Vaucheria foram investigados em 105 riachos do sul do Brasil. As variáveis abióticas foram correlacionadas com a ocorrência das espécies. Três espécies foram identificadas de acordo com as características do gametângio: V. geminata (Vauch.) D.C., V. taylorii Blum e V. sessilis (Vauch.) D.C., este último sendo relatado pela primeira vez no Brasil. Os resultados deste estudo sugerem que Vaucheria é influenciada pelas características ambientais, ocorrendo principalmente em pH neutro a levemente ácido, baixa turbidez, velocidade da correnteza lenta e em riachos parcialmente sombreados. Esta combinação de variáveis parece ser a mais favorável para o estabelecimento da população de Vaucheria em ambientes lóticos, independentemente do bioma. (The genus Vaucheria D.C. [Vaucheriaceae, Xanthophyceae] in Southern Brazil: taxonomic and ecology aspects). Taxonomic survey and environmental occurrence of the genus Vaucheria were investigated in 105 streams from Southern Brazil. Abiotic variables were correlated to species occurrence. Three species were identified according to gametangia characteristics: V. geminata (Vauch.) D.C., V. taylorii Blum and V. sessilis (Vauch.) D.C.; the latter is reported for the first time in Brazil. The results of this survey suggest that Vaucheria is influenced by environmental characteristics, occurring mainly, in neutral to slightly acidic pH, low turbidity, slow current velocity and in partly shaded streams. This combination of variables seems to be the most favorable in the Vaucheria population establishment in lotic habitats independently of biome. Universidade Estadual Paulista FCL Universidade Federal da Integração Latino-Americana Universidade Estadual Paulista FCL

Species traits, such as breeding system, phylum and growth form and habitat characteristics are shown to influence reproductive performance of liverworts and mosses in the Brazilian Atlantic Rainforest, and drive life-history differentiation among species and populations., Background and aims Short life cycles and trade-offs linked to breeding systems make bryophytes good models for the study of plant reproductive strategies. Our aim was to test if differences in sexual reproductive performance of bryophytes in tropical rainforests are driven by the breeding system of the species (monoicous or dioicous) or are mainly affected by the habitat. Methodology The reproductive performance (sexual branches, gametangia (sex organs), fertilization and sporophyte production) of 11 species was repeatedly monitored and analysed from populations at sea-level and montane sites of a Brazilian Atlantic rainforest over 15 months. Principal results Monoicous species had the highest reproductive performance, particularly for sexual branches, fertilized gametangia and sporophyte production. Species at the sea-level site produced more sexual branches and had more female-biased sex ratios of gametangia than species in the montane site. Fertilizations were more frequent at the montane site, but sporophyte frequency was similar between the two sites. Fertilization tended to occur mostly in the periods of heavy rain (October to December). Conclusions Breeding system is not the only major influence on the reproductive performance of bryophytes. We show that habitat is also an important factor determining life-history differentiation. Female-biased sex ratios and low rates of fertilization are seen to be compensated for by high production of reproductive structures at the initial phases of the reproductive cycle.