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Summary New results have added to our knowledge about the gametophyte-sporophyte junction in bryophytes, hornworts and pteridophytes and its significance for archegoniate land plant evolution. Bryophyta (liverworts and mosses) show a uniform structure: the sporophyte foot is separated from the surrounding gametophyte tissue by a placental space. At maturity the space is in most cases filled with residues of collapsed cells of gametophyte origin. The taxa with a placental space represent the bryophyte lineage of land plant evolution, indicating a common ancestor of the bryophyte groups Hepaticophytina and Bryophytina. To emphasize the separate position of Fossombronia within liverworts, the new class Fossombroniopsida is proposed. In Anthocerotophyta and Psilotopsida sporophyte haustorial cells intermingle resp. interdigitate with gametophyte transfer cells, and electron-dense fibrillar material fills the interface. In Lycopodiopsida, Equisetopsida and Pteridopsida, a direct contact exists between gametophyte and sporophyte placental layers. In some cases, sporophyte placental cells tend to interdigitate between gametophyte placental cells. No residues of collapsed gametophyte cells are found in the interface between the two generations.

Hornworts (Anthocerotophyta) are a main lineage of land plants but they are exceedingly rare as fossils. The only fossil hornwort described from amber has been interpreted as the best preserved fossil of this group. Reinvestigation of this fossil revealed that this Miocene amber inclusion represents a poorly preserved flower that shows some features of the Caesalpinioideae subfamily of the Fabaceae.

A hornwort is reported from Dominican amber (Eocene–Oligocene). The specimen shows the horn-like sporophytes typical for this group of plants and can be placed into the Dendrocerotaceae, although an exact placement in Dendroceros or Megaceros cannot be made, it is the first record of a fossil hornwort.

Hornworts are considered the sister group to vascular plants, but their fungal associations remain largely unexplored. The ancestral symbiotic condition for all plants is, nonetheless, widely assumed to be arbuscular mycorrhizal with Glomeromycota fungi. Owing to a recent report of other fungi in some non-vascular plants, here we investigate the fungi associated with diverse hornworts worldwide, using electron microscopy and molecular phylogenetics. We found that both Glomeromycota and Mucoromycotina fungi can form symbioses with most hornworts, often simultaneously. This discovery indicates that ancient terrestrial plants relied on a wider and more versatile symbiotic repertoire than previously thought, and it highlights the so far unappreciated ecological and evolutionary role of Mucoromycotina fungi.

In cyanobacteria-plant symbioses, the symbiotic nitrogen-fixing cyanobacterium has low photosynthetic activity and is supplemented by sugars provided by the plant partner. Which sugars and cyanobacterial sugar uptake mechanism(s) are involved in the symbiosis, however, is unknown. Mutants of the symbiotically competent, facultatively heterotrophic cyanobacterium Nostoc punctiforme were constructed bearing a neomycin resistance gene cassette replacing genes in a putative sugar transport gene cluster. Results of transport activity assays using 14C-labeled fructose and glucose and tests of heterotrophic growth with these sugars enabled the identification of an ATP-binding cassette-type transporter for fructose (Frt), a major facilitator permease for glucose (GlcP), and a porin needed for the optimal uptake of both fructose and glucose. Analysis of green fluorescent protein fluorescence in strains of N. punctiforme bearing frt::gfp fusions showed high expression in vegetative cells and akinetes, variable expression in hormogonia, and no expression in heterocysts. The symbiotic efficiency of N. punctiforme sugar transport mutants was investigated by testing their ability to infect a nonvascular plant partner, the hornwort Anthoceros punctatus. Strains that were specifically unable to transport glucose did not infect the plant. These results imply a role for GlcP in establishing symbiosis under the conditions used in this work.

The genus Notothylas in China contains four species. One new species, Notothylas yunnanensis, is described and illustrated. The new species is characterized by each proximal spore surface with a small central hollow, irregularly arranged, rectangular to quadrate epidermal cells of the capsule, and absence of a special dehiscence line in the capsule. A key to the species of Notothylas in China is provided.

Amino acid uptake and utilization of various nitrogen sources (amino acids, nitrite, nitrate and ammonia) were studied in Nostoc ANTH and i ts mu tant (Het(-)Nif(-)) isolate defective in heterocyst formation and N2-fixation. Both parent and its mutant grew at the expense of glutamine, asparagine and arginine as a source of fixed-nitrogen. Growth was better in glutamine-and asparagine-media as compared to that in arginine media. Glutamine and asparagine repressed heterocyst formation, N2-fixation and nitrate reduction in Nostoc ANTH, but arginine did so only partially. The poor growth in arginine-medium was not due to poor uptake rates, since the uptake rates were not significantly different from those for glutamine or asparagine. The glutamine synthetase activity remained unaffected during cultivation in media containing any one of the three amino acids tested. The uptake of amino acids was substrate-inducible, energy-dependent and required de novo protein synthesis. Nitrate and ammonium repressed ammonium uptake, but did not repress uptake of amino acids. In N2-medium (BG-11(0)), the uptake of ammonium and amino acids in the mutant was significantly higher than its parent strain. This was apparently due to nitrogen limitation since the mutant was unable to fix N2 and the growth medium lacked combined-N.

BACKGROUND: Land plants (embryophytes) are monophyletic and encompass four major clades: liverworts, mosses, hornworts and polysporangiophytes. The liverworts are resolved as the earliest divergent lineage and the mosses as sister to a crown clade formed by the hornworts and polysporangiophytes (lycophytes, monilophytes and seed plants). Alternative topologies resolving the hornworts as sister to mosses plus polysporangiophytes are less well supported. Sporophyte development in liverworts depends only on embryonic formative cell divisions. A transient basal meristem contributes part of the sporophyte in mosses. The sporophyte body in hornworts and polysporangiophytes develops predominantly by post-embryonic meristematic activity. SCOPE: This paper explores the origin of the sporophyte shoot in terms of changes in embryo organization. Pressure towards amplification of the sporangium-associated photosynthetic apparatus was a major driver of sporophyte evolution. Starting from a putative ancestral condition in which a transient basal meristem produced a sporangium-supporting seta, we postulate that in the hornwort-polysporangiophyte lineage the basal meristem acquired indeterminate meristematic activity and ectopically expressed the sporangium morphogenetic programme. The resulting sporophyte body plan remained substantially unaltered in hornworts, whereas in polysporangiophytes the persistent meristem shifted from a mid-embryo to a superficial position and was converted into an ancestral shoot apical meristem with the evolution of sequential vegetative and reproductive growth. CONCLUSIONS: The sporophyte shoot is interpreted as a sterilized sporangial axis interpolated between the embryo and the fertile sporangium. With reference to the putatively ancestral condition found in mosses, the sporophyte body plans in hornworts and polysporangiophytes are viewed as the product of opposite heterochronic events, i.e. an anticipation and a delay, respectively, in the development of the sporangium. In either case the result was a pedomorphic sporophyte permanently retaining juvenile characters.

There are 300 species belonging to the Anthocerotophyta (hornworts), but only a few species have been studied chemically. It is known that the chemical constituents of the Anthocerotophyta are very distinct from the other two classes, the Marchantiophyta and Bryophyta. Previously, several sesquiterpenes and sterols were detected only by GC/MS, while some lignans and cinnamic acid derivatives were isolated from certain hornworts (40). Although the chemical constituents of hornworts have not been investigated fully, Megaceros flagellaris is chemically quite different from the other five hornwort genera, Anthoceros, Dendroceros, Folioceros, Notothylas, and Paeroceros to have been studied so far (40). Furthermore, it is suggested from the presence of simple chemical constituents that the Anthocerotophyta are a more primitive class of plants than the Marchantiophyta (40, 140). Since 1995, several mono-, sesqui-, and phytane-type diterpenoids, rosmarinic glutamic acid derivatives, and chlorophyll degradation products have been isolated from a limited number of hornworts, as shown in Tables 6.1–6.6.

† Background Molecular phylogeny has resolved the liverworts as the earliest-divergent clade of land plants and mosses as the sister group to hornworts plus tracheophytes, with alternative topologies resolving the hornworts as sister to mosses plus tracheophytes less well supported. The tracheophytes plus fossil plants putatively lacking lignified vascular tissue form the polysporangiophyte clade. † Scope This paper reviews phylogenetic, developmental, anatomical, genetic and paleontological data with the aim of reconstructing the succession of events that shaped major land plant lineages. † Conclusions Fundamental land plant characters primarily evolved in the bryophyte grade, and hence the key to a better understanding of the early evolution of land plants is in bryophytes. The last common ancestor of land plants was probably a leafless axial gametophyte bearing simple unisporangiate sporophytes. Water-conducting tissue, if present, was restricted to the gametophyte and presumably consisted of perforate cells similar to those in the early-divergent bryophytes Haplomitrium and Takakia. Stomata were a sporophyte innovation with the possible ancestral functions of producing a transpiration-driven flow of water and solutes from the parental gametophyte and facilitating spore separation before release. Stomata in mosses, hornworts and polysporangiophytes are viewed as homologous, and hence these three lineages are collectively referred to as the ‘stomatophytes’. An indeterminate sporophyte body (the sporophyte shoot) developing from an apical meristem was the key innovation in polysporangiophytes. Poikilohydry is the ancestral condition in land plants; homoiohydry evolved in the sporophyte of polysporangiophytes. Fungal symbiotic associations ancestral to modern arbuscular mycorrhizas evolved in the gametophytic generation before the separation of major present-living lineages. Hydroids are imperforate water-conducting cells specific to advanced mosses. Xylem vascular cells in polysporangiophytes arose either from perforate cells or de novo. Food-conducting cells were a very early innovation in land plant evolution. The inferences presented here await testing by molecular genetics.

The bryophytes contain the Marchantiophyta (liverworts), Bryophyta (mosses) and Anthocerotophyta (hornworts) among which the Marchantiophyta contain cellular oil body and they produce a number of terpenoids, aromatic compounds and acetogenins, several of which show interesting biological activity such as allergenic contact dermatitis, insecticide, insect antifeedant, cytotoxic, piscicidal, muscle relaxing, plant growth regulatory, anti-HIV, DNA polymerase beta inhibitory, anti-obesity, neurotrophic, NO production inhibitory, antimicrobial and antifungal activities. The isolation and chemical structures of biologically active compounds and their total synthesis are reviewed.

The presence of Nostoc in longitudinally oriented schizogenous canals is a feature that separates Leiosporoceros from all other hornworts and represents a novel symbiotic arrangement in land plants. In surface view, Nostoc canals are visible as elongated, dichotomously branched blue-green strands. All other hornworts develop numerous discrete globose colonies through continuous production of mucilage clefts as avenues for multiple invasions within a single thallus. To elucidate the anatomy and development of the unusual Nostoc strands in Leiosporoceros, we examined sporeling development in culture and the structure of strands in field-collected plants using light and electron microscopy. Rosette-like sporelings have mucilage clefts scattered along swollen apices. All field specimens were strap-shaped, contained Nostoc, and lacked mucilage clefts. Nostoc strands are located in the center of the thallus and develop behind the apical cell by separation of the middle lamella between apical derivatives. Strands elongate and branch in synchrony with apical growth, and thus only a single invasion is required for strand production. Two distinct ultrastructural morphotypes in the collections suggest nonspecificity of Nostoc. We speculate that Nostoc enters the thallus in the sporeling stage through mucilage clefts, and once colonies are established, cleft production ceases.

PREMISE OF THE STUDY: We present here new bryophyte-specific primers that permit retrieval of 17 slowly evolving plastid genes and their associated introns and intergenic spacers. These regions were chosen to facilitate accurate phylogenetic inference across a broad range of mosses and other bryophytes. METHODS AND RESULTS: We developed 78 new primers for the targeted regions using an initial sampling of exemplar bryophytes and other green plants, to complement those used in vascular plants. We assessed the ability of the new primers to amplify and sequence these regions using a test set of 11 additional exemplar bryophytes. CONCLUSIONS: We show that the newly designed primers facilitate ready retrieval of 14 of 17 targeted regions from a broad range of bryophyte taxa. These primers should prove useful for future studies of bryophyte phylogeny.

Uptake 14CO2 from air and accumulation of 14C in the hornwort were studied by using the isotope-tracer techniques in order to get a better understanding of the environmental behavior of 14CO2. And the possibility of hornwort used as the indicator plant in the supervisor of 14CO2 air pollution was discussed. The results show that the hornwort could uptake 14CO2 from the air by some way and formed an accumulating trend. The main way was that the hornwort absorbed free 14CO2 and H 14CO3- from the water through photosynthesis. During the introducing 14CO2, the increasing rate of 14C specific activity in dry hornwort and fresh hornwort were between 91.9-95.6 Bq/(g x d) and 6.1-6.3 Bq/(g x d), respectively, which was roughly equal to the increasing rate in the wheat. The results indicate that the hornwort had strong ability of absorbing 14CO2 indirectly through water. The hornwort has an certain concentration of 14CO2. And the concentration factor (CF) values rise with the introduction of 14CO2 and decline slowly after it reached the maximum value. Owing to its accumulation of 14CO2, hornwort can be used as the indicator plant in the supervisor of 14CO2 air pollution.

The physiological effects of 4 herbicides (butachlor, quinclorac, bensulfuron-methyl and atrazine) on 3 submerged macrophytes (Ceratophyllum demersum, Vallisneria natans and Elodea nuttallii) were tested in laboratory. The variables of the relative growth rate and the photosynthetic pigment content showed that all of the tested herbicides affected the growth of the plants obviously, even at the lowest concentration (0.0001 mg/L). Except for the C. demersum treated with quinclorac at 0.005 and 0.01 mg/L, the relative growth rates of the plants were inhibited significantly (p < 0.01). Statistical analysis of chlorophyll a (Chl-a) contents was carried out with both the t-test and one-way ANOVA to determine the difference between the treatment and control. The results showed that Chl-a contents of the plants in all treatment groups were affected by herbicides significantly, except for the C. demersum treated with bensulfuron-methyl at 0.0005 mg/L. The decrease in Chl-a content was positively correlated to the dosage of the herbicides in most treatment groups. It was suggested that herbicides in water bodies might potentially affect the growth of aquatic macrophytes. Since the Chl-a content of submerged macrophytes responded to the stress of herbicides sensitively and directly, it could be used as a biomaker in environmental monitoring or in the ecological risk assessment of herbicide contamination.

Foram identificados 22 táxons de antóceros e hepáticas que são novas ocorrências para o Estado do Rio Grande do Sul (1 antócero e 21 hepáticas). Oito famílias e 15 gêneros pertencem à Marchantiophyta e um gênero e uma família à Anthocerotophyta. As famílias mais bem representadas são Lejeuneaceae, Aneuraceae e Metzgeriaceae. Neesioscyphus argillaceus (Nees) Grolle e Lejeunea cancellata Nees & Mont. tiveram sua distribuição geográfica ampliada. Estão sendo apresentadas ilustrações e distribuição geográfica para todos os táxons. Twenty two taxa (1 hornwort and 21 liverworts) were identified with new records to Rio Grande do Sul State. Eight families and 15 genera belong to Marchantiophyta and one genus and one family belong to Anthocerotophyta. The most representative families are Lejeuneaceae, Aneuraceae and Metzgeriaceae. Neesioscyphus argillaceus (Nees) Grolle and Lejeunea cancellata Nees & Mont. were cited for new sites. All species are illustrated and geographic distributions are presented.

Foram identificados 22 táxons de antóceros e hepáticas que são novas ocorrências para o Estado do Rio Grande do Sul (1 antócero e 21 hepáticas). Oito famílias e 15 gêneros pertencem à Marchantiophyta e um gênero e uma família à Anthocerotophyta. As famílias mais bem representadas são Lejeuneaceae, Aneuraceae e Metzgeriaceae. Neesioscyphus argillaceus (Nees) Grolle e Lejeunea cancellata Nees & Mont. tiveram sua distribuição geográfica ampliada. Estão sendo apresentadas ilustrações e distribuição geográfica para todos os táxons.

Land plants possess some of the most unusual mitochondrial genomes among eukaryotes. However, in early land plants these genomes resemble those of green and red algae or early eukaryotes. The question of when during land plant evolution the dramatic change in mtDNAs occurred remains unanswered. Here we report the first completely sequenced mitochondrial genome of the hornwort, Megaceros aenigmaticus, a member of the sister group of vascular plants. It is a circular molecule of 184,908 base pairs, with 32 protein genes, 3 rRNA genes, 17 tRNA genes, and 30 group II introns. The genome contains many genes arranged in the same order as in those of a liverwort, a moss, several green and red algae, and Reclinomonas americana, an early-branching eukaryote with the most ancestral form of mtDNA. In particular, the gene order between mtDNAs of the hornwort and Physcomitrella patens (moss) differs by only 8 inversions and translocations. However, the hornwort mtDNA possesses 4 derived features relative to green alga mtDNAs--increased genome size, RNA editing, intron gains, and gene losses--which were all likely acquired during the origin and early evolution of land plants. Overall, this genome and those of other 2 bryophytes show that mitochondrial genomes in early land plants, unlike their seed plant counterparts, exhibit a mixed mode of conservative yet dynamic evolution.

This paper is a survey of the current state of molecular studies on bryophyte phylogeny. Molecular data have greatly contributed to developing a phylogeny and classification of bryophytes. The previous traditional systems of classification based on morphological data are being significantly revised. New data of the authors are presented on phylogeny of Hypnales pleurocarpous mosses inferred from nucleotide sequence data of the nuclear DNA internal transcribed spacers ITS1-2 and the trnL-F region of the chloroplast genome.

Prior to the publication of the world checklist of hornworts and liverworts (Söderström et al., in press) some taxa still need to be validated, transferred or synonymized. We are here dealing with the remaining nomenclatural issues among the Anthocerotophyta. Several taxa have not been typified properly and we are here suggesting several new lectotypes to stabilize the nomenclature.

The anatomy and morphology of six species of Anthoceros found in central Mexico are described. Anthoceros hispidus is reported new to Mexico. A key to the species of the genus in the region is provided.

RNA editing alters the nucleotide sequence of an RNA molecule so that it deviates from the sequence of its DNA template. Different RNA-editing systems are found in the major eukaryotic lineages, and these systems are thought to have evolved independently. In this study, we provide a detailed analysis of data on C-to-U editing sites in land plant chloroplasts and propose a model for the evolution of RNA editing in land plants. First, our data suggest that the limited RNA-editing system of seed plants and the much more extensive systems found in hornworts and ferns are of monophyletic origin. Further, although some eukaryotic editing systems appear to have evolved to regulate gene expression, or at least are now involved in gene regulation, there is no evidence that RNA editing plays a role in gene regulation in land plant chloroplasts. Instead, our results suggest that land plant chloroplast C-to-U RNA editing originated as a mechanism to generate variation at the RNA level, which could complement variation at the DNA level. Under this model, many of the original sites, particularly in seed plants, have been subsequently lost due to mutation at the DNA level, and the function of extant sites is merely to conserve certain codons. This is the first comprehensive model for the evolution of the chloroplast RNA-editing system of land plants and may also be applicable to the evolution of RNA editing in plant mitochondria.

Cell suspension cultures of the hornwort Anthoceros agrestis Paton (Anthocerotaceae) were cultivated and characterized in CB-media containing 2 and 4% sucrose. The suspension cells accumulated rosmarinic acid up to 5.1% of the cell dry weight as well as caffeoyl-4'-hydroxyphenyllactate. Moreover, a more hydrophilic compound was detected which was isolated and identified as rosmarinic acid 3'-O-beta-D-glucoside, a new rosmarinic acid derivative. This new rosmarinic acid derivative was found up to 1.0% of the cell dry weight in suspension cells of A. agrestis.

Nesse levantamento foram encontrados 133 táxons no Estado de Mato Grosso do Sul, sendo um pertencente à divisão Anthocerotophyta em um gênero e uma família, 83 pertencentes à divisão Bryophyta, distribuídos em 54 gêneros e 27 famílias, e 49 à divisão Hepatophyta, distribuídos em 27 gêneros e 13 famílias. Destes, 100 (1 antócero, 59 musgos e 40 hepáticas) são novas citações para o Estado. In this taxonomic survey 133 taxa were found in Mato Grosso do Sul State, one belonging to Anthocerotophyta, distributed into one genus and one family, 83 belonging to Bryophyta, distributed into 54 genera and 27 families, and 49 belonging to Hepatophyta, distributed into 27 genera and 13 families. Of these, 100 (one hornworts, 59 mosses and 40 hepatics) are new records for the State.

p.437-458 Submitted by Texeira Ana (atanateixeira@gmail.com) on 2012-08-31T17:06:17Z No. of bitstreams: 1 Yano, Olga.pdf: 119644 bytes, checksum: 11614f4cc22ca670a711202e662527c4 (MD5) Made available in DSpace on 2012-08-31T17:06:17Z (GMT). No. of bitstreams: 1 Yano, Olga.pdf: 119644 bytes, checksum: 11614f4cc22ca670a711202e662527c4 (MD5) Previous issue date: 2004-07 Nesse levantamento foram encontrados 133 táxons no Estado de Mato Grosso do Sul, sendo um pertencente à divisão Anthocerotophyta em um gênero e uma família, 83 pertencentes à divisão Bryophyta, distribuídos em 54 gêneros e 27 famílias, e 49 à divisão Hepatophyta, distribuídos em 27 gêneros e 13 famílias. Destes, 100 (1 antócero, 59 musgos e 40 hepáticas) são novas citações para o Estado. São Paulo

RNA editing affecting chloroplast and mitochondrial genomes has been identified in all major clades of land plants. The frequency of edited sites varies greatly between lineages but hornworts represent an extreme in propensity for editing in both their chloroplast and mitochondrial genomes. cDNA sequences from seven taxonomically diverse hornwort rbcL sequences combined with a survey of 13 additional DNA sequences for potential edited sites demonstrate the presence of 62 edited sites and predict a minimum of 10 additional sites. These 72 total edited sites represent 43 C-to-U and 28 U-to-C nucleotide conversions, with 1 site exhibiting editing in both directions. With one exception, all taxa are heavily edited, with each having from 20 to 34 edited sites. However, a single sample, Leiosporoceros, is shown to lack edited sites. Phylogenetic reconstruction of hornworts results in ambiguous resolution of Leiosporoceros depending on whether edited sites are maintained or eliminated from the analyses. Depending on the inferred relationship of Leiosporoceros to the hornworts, at least two explanations for the origin and maintenance of pervasive editing in hornworts are possible. The absence of edited sites in Leiosporoceros could represent either the absence or a low level of editing ability in the common ancestor of hornworts, as represented by Leiosporoceros, or the loss of editing sites in this lineage after the primary diversification events in the group.

In phylogenetic trees generated from partial trnL(UAA) intron sequences, the hornworts (represented by nine species from the genera Anthoceros, Dendroceros, Megaceros, Notothylas and Phaeoceros) are resolved as a monophyletic group and are separated from the clades of mosses, liverworts and tracheophytes. A secondary structure of the trnL(UAA) intron of Anthoceros agrestis is presented, displaying the arrangement of the stem-loop regions P1-P9. Compensatory base-pair changes (coevolutionary sites) are detected in regions P4/5 and P9 within the hornwort sequences. The original homology of the most variable region, P8, cannot be detected anymore due to the extremely fast divergent evolution of this segment in the major land plant groups. Similarly, a high sequence divergence occurs in the trnL-trnF intergenic spacer. Apart from synapomorphic substitutions in the trnL(UAA) intron, the hornworts are characterised by a large P6 region consisting of many repetitive elements. The molecular data therefore support the hornworts as representing an independent land plant lineage (Anthocerotophyta). Although relationships between hornworts and the other land plant groups remain unresolved in the trnL(UAA) intron trees, it is rather unlikely that bryophytes are monophyletic in their traditional circumscription, i.e. comprising hornworts, mosses and liverworts.

Bryophytes consisting of three division, there are Bryophyta (mosses), Marchantiophyta (liverworts) dan Anthocerotophyta (hornworts). Marchantiophyta are divided in two types, leafy liverworts and thallose liverworts. Mount Ungaran which has many diversity of Bryophytes but research about Bryophytes in this area are sparse. The aim of this research was to observe diversity of Marchantiophyta on tree trunks in montane zone (altitudes 1300 to 2050 meters above sea level). Sampling was conducted in April and May 2012 at three different altitudes ( 1355, 1660, and 2040 meters above sea level). Identification of Bryophytes was carried out at Laboratorium of Ecology and Biosistematics, Department Biology, Faculty of Science and Mathematics, Diponegoro University, Semarang, Indonesia. The results shown there are 9 families with 26 species belonging to the division Marchantiophyta. Keywords: Epiphytic Marchantiophyta, Mount Ungaran, diversity, montana zone.

Background Whether male and female gametes are produced by single or separate individuals shapes plant mating and hence patterns of genetic diversity among and within populations. Haploid-dominant plants (“bryophytes”: liverworts, mosses and hornworts) can have unisexual (dioicous) or bisexual (monoicous) gametophytes, and today, 68% of liverwort species, 57% of moss species, and 40% of hornwort species are dioicous. The transitions between the two sexual systems and possible correlations with other traits have been studied in liverworts and mosses, but not hornworts. Here we use a phylogeny for 98 of the 200 species of hornworts, the sister group to vascular plants, representing roughly equal proportions of all monoicous and all dioicous species, to test whether transitions in sexual systems are predominantly from monoicy to dioicy as might be expected based on studies of mosses. We further investigate possible correlations between sexual system and spore size, antheridium number, ploidy level, and diversification rate, with character selection partly based on findings in mosses and liverworts. Results Hornworts underwent numerous transitions between monoicy and dioicy. The transition rate from dioicy to monoicy was 2× higher than in the opposite direction, but monoicous groups have higher extinction rates; diversification rates do not correlate with sexual system. A correlation important in mosses, that between monoicy and polyploidy, apparently plays a small role: of 20 species with chromosome counts, only one is polyploid, the monoicous Anthoceros punctatus. A contingency test revealed that transitions to dioicy were more likely in species with small spores, supporting the hypothesis that small but numerous spores may be advantageous for dioicous species that depend on dense carpets of gametophytes for reproductive assurance. However, we found no evidence for increased antheridium-per-chamber numbers in dioicous species. Conclusions Sexual systems in hornworts are labile, and the higher number of extant monoicous species (60%) may be largely due to frequent transitions to monoicy.

Riassunto Methodological difficulties encountered in preparing the new checklist and the new red list of the 279 liverworts and hornworts existing currently in Italy are explained. Special difficulties for their observation and collection in the field and for their identification are detailed. The main obstacles to a better knowledge of the Italian hepaticological flora are discussed. A synthetic view of the threatened species is given, drawing attention to the special importance of Italy for the protection of many species at the European level.

The genus Anthoceros (Anthocerotaceae, Anthocerotopsida) in China is reviewed. Five species and one variety are recognized. Anthoceros alpinus , A. bharadwajii , and A. subtilis , are reported new to China. Aspiromitus areolatus and Anthoceros esquirolii are proposed as new synonyms of Folioceros fuciformis and Phaeoceros carolinianus , respectively. A key to the species of Anthoceros in China is provided.

When Linnaeus (Sp. PI.: 1139. 1753) named the genus Anthoceros he included three species, namely, A. punctatus, A. laevis, and A. multifidus. Anthoceros multifidus was later removed from the genus and transferred to Riccardia by Gray (Nat. Arr. Brit. PI.: 684. 1821 'Riccardius') leaving two of the original species in the genus Anthoceros. Anthoceros punctatus was selected as the generitype by Proskauer (Ann. Bot., n.s. 12: 259. 1948). His selection remained uncontested until Schuster (J. Hattori Bot. Lab. 26: 299. 1963) suggested that Proskauer should have selected A. laevis as the type rather than A. punctatus. That is because Proskauer later decided (Bull. Torrey Bot. Club 78: 346, 1951) that these two original species of Anthoceros actually represented two different genera. Since he had selected A. punctatus as the type, it had to remain with Anthoceros, so he transferred A. laevis to his new genus Phaeoceros (Proskauer I.c., 1951). Anthoceros punctatus had long been considered to be conspecific with Aspiromitus husnotii Steph., the generitype of Aspiromitus Steph. (Proskauer, I.c., 1948: 262), and Schuster (I.c., 1963) stated that "Aspiromitus, typified by A. husnotii (= A. punctatus) must be used for one of the two elements originally included in Anthoceros by Linnaeus, and Anthoceros must be retained for the other ('law of residues')". Following his logic, the two species of Linnaeus would then be Anthoceros laevis and Aspiromitus punctatus; he did not, however, make any new combinations in 1963. Schljakov (Novosti Sist. Niz. Rast. 13: 225. 1976) agreed with Schuster (I.c., 1963) and implicitly lectotypified Anthoceros with Anthoceros laevis, making the new combination Aspiromitus punctatus (L.) Schljak. Grolle (Acta Bot. Fenn. 121: 5. 1983) pointed out that such a later lectotypification was contrary to the provisions of the ICBN, particularly with the removal of any appeal to the "law of residues" in the edition adopted at the Sydney Congress of 1981 (Voss & al., Regnum Veg. 111. 1983) and had to be rejected. That would have been the case except for the provision of the ICBN, first adopted at the Seattle Congress in 1969 (cf. Art. 8 (last clause) in Stafleu & al., Regnum Veg. 82. 1972), and now expressed as Article 10.5(b) of the ICBN (Greuter & al., Regnum Veg. 138. 2000) that a choice of lectotype for the name of a genus or subdivision of a genus may be superseded if ". . . it was based on a largely mechanical method of selection". The selection by Proskauer (l.c., 1948: 262) was obviously mechanical since he wrote: "Anthoceros punctatus was described by Linne (1753) as the first species of Anthoceros. It is here, therefore, considered as the type of the genus". Although the actions of Schuster (l.c., 1963) and Schljakov (l.c.) do not represent formal designation of a type as required by Art. 7.11 of the ICBN, more recently Schuster (Hepaticae and Anthocerotae of North America 6: 745. 1992), following his description of Anthoceros, wrote: "Type. Anthoceros laevis L. The reasons for the present type designation are discussed at length, below". Although this later designation was based solely upon the "law of residues" with no mention whatsoever of the mechanical choice by Proskauer (l.c. 1948: 262), Art. 10 Ex. 7, a "voted example", makes clear that any later type designation that meets the requirements of Art. 7.11 supersedes a choice "based on a largely mechanical method of selections". Therefore, unless the Proskauer designation of A. punctatus is conserved as the type of the name Anthoceros, it must be considered to have been superseded by Schuster's (I.c. 1992: 745) choice of A. laevis. With A. laevis as the generitype, the species of Phaeoceros must either be returned to or transferred to Anthoceros and all species now considered to be members of Anthoceros must be transferred to Aspiromitus. Schuster (l.c., 1992) and Schljakov (l.c.) have already begun this lengthy task to a very limited extent. Not only will the number of new combinations be high, including well over 100 of the 293 binomials listed by Bonner (in Index Hepat. 2. 1962) under Anthoceros, the confusion this will cause will be unprecedented. This will likewise result in changing the generic name for 131 sequences

A recent investigation on the bryophytes of Darjeeling has revealed the occurrence of 12 taxa of hornworts (anthocerotes) in this region. Of these, Anthoceros punctatus, Folioceros assamicus, Phaeoceros himalayensis, Notothylas indica, N. khasiana, N. levieri are new to Darjeeling, while Anthoceros alpinus, a critically endangered species, is new to eastern Himalaya and Notothylas khasiana is an extremely rare species.

The bryophytes contain the Marchantiophyta (liverwort), Bryophyta (moss) and Anthocerotophyta (hornwort) among which the Marchantiophyta contain cellular oil body and they produce a number of mono-, sesqui- and diterpenoids, aromatic compounds like bibenzyl, bis(bibenzyls) and acetogenins. Several of these compounds show interesting biological activity such as insecticide, insect antifeedant, cytotoxic, piscicidal, muscle relaxing, allergenic contact dermatitis, anti-HIV, DNA polymerase p, 5-lipoxygenase, calmodium inhibitory, anti-obesity, neurotrophic, cyclooxygenase, hyaluronidase and NO production inhibitory, antimicrobial and antifungal activities. Each liverwort biosynthesizes peculiar components, which are valuable for classification of liverworts. The typical chemical structures and bioactivity of the selected liverwort constituents as well as chemosystematics of several species of the Marchantiophyta are surveyed.

Four species within the hornwort genus Phaeoceros are recognized and described for Australia: the cosmopolitan P. carolinianus (Michx.) Prosk.; two new combinations of taxa endemic to Australia—P. evanidus (Steph.) Cargill & Fuhrer comb. nov., P. inflatus (Steph.) Cargill & Fuhrer comb. nov.; and a species new to science, P. engelii Cargill & Fuhrer sp. nov. A key to all four species is also given.