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32-543: Embryophyta Charophyta ( UK : / k ə ˈ r ɒ f ɪ t ə , ˌ k ær ə ˈ f aɪ t ə / ) is a group of freshwater green algae , called charophytes ( / ˈ k ær ə ˌ f aɪ t s / ), sometimes treated as a division , yet also as a superdivision or an unranked clade . The terrestrial plants, the Embryophyta emerged deep within Charophyta, possibly from terrestrial unicellular charophytes, with

64-490: A and b to harvest the light energy in sunlight for carbon fixation from carbon dioxide and water in order to synthesize carbohydrates while releasing oxygen as a byproduct . The Embryophytes emerged either a half-billion years ago, at some time in the interval between the mid- Cambrian and early Ordovician , or almost a billion years ago, during the Tonian or Cryogenian, probably from freshwater charophytes ,

96-419: A and b , generally giving them a bright green color. Embryophyte cells also generally have an enlarged central vacuole enclosed by a vacuolar membrane or tonoplast, which maintains cell turgor and keeps the plant rigid. In common with all groups of multicellular algae they have a life cycle which involves alternation of generations . A multicellular haploid generation with a single set of chromosomes –

128-404: A gametophyte . In embryophytes (land plants) the zygote will instead give rise to a multicellular sporophyte . Except from land plants, retention of the zygote is only known from some species in one group of green algae; the coleochaetes . In these species the zygote is corticated by a layer of sterile gametophytic cells. Another similarity is the presence of sporopollenin in the inner wall of

160-470: A clade of multicellular green algae similar to extant Klebsormidiophyceae . The emergence of the Embryophytes depleted atmospheric CO 2 (a greenhouse gas ), leading to global cooling , and thereby precipitating glaciations . Embryophytes are primarily adapted for life on land, although some are secondarily aquatic . Accordingly, they are often called land plants or terrestrial plants. On

192-465: A microscopic level, the cells of charophytes are broadly similar to those of chlorophyte green algae, but differ in that in cell division the daughter nuclei are separated by a phragmoplast . They are eukaryotic , with a cell wall composed of cellulose and plastids surrounded by two membranes. The latter include chloroplasts , which conduct photosynthesis and store food in the form of starch , and are characteristically pigmented with chlorophylls

224-399: A single cell. In the bryophytes the sporophyte remains dependent on the gametophyte, while in all other embryophytes the sporophyte generation is dominant and capable of independent existence. Embryophytes also differ from algae by having metamers . Metamers are repeated units of development, in which each unit derives from a single cell, but the resulting product tissue or part is largely

256-416: Is a short, filamentous and unbranched algae surrounded by a mucilaginous sheath, which often disintegrates to diads and unicells. The cells in Charophyta algae are all haploid , except during sexual reproduction, where a diploid unicellular zygote is produced. The zygote becomes four new haploid cells through meiosis, which will develop into new algae. In multicellular forms these haploid cells will grow into

288-584: The Ordovician , streptophytes invaded the land and began the evolution of the embryophyte land plants. Present day embryophytes form a clade. Becker and Marin speculate that land plants evolved from streptophytes because living in fresh water pools pre-adapted them to tolerate a range of environmental conditions found on land, such as exposure to rain, tolerance of temperature variation, high levels of ultra-violet light, and seasonal dehydration. The preponderance of molecular evidence as of 2006 suggested that

320-570: The gametophyte – produces sperm and eggs which fuse and grow into a diploid multicellular generation with twice the number of chromosomes – the sporophyte which produces haploid spores at maturity. The spores divide repeatedly by mitosis and grow into a gametophyte, thus completing the cycle. Embryophytes have two features related to their reproductive cycles which distinguish them from all other plant lineages. Firstly, their gametophytes produce sperm and eggs in multicellular structures (called ' antheridia ' and ' archegonia '), and fertilization of

352-444: The mosses (Bryophyta), hornworts (Anthocerotophyta), and liverworts (Marchantiophyta), are relatively small plants, often confined to environments that are humid or at least seasonally moist. They are limited by their reliance on water needed to disperse their gametes ; a few are truly aquatic. Most are tropical, but there are many arctic species. They may locally dominate the ground cover in tundra and Arctic–alpine habitats or

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384-557: The Viridiplantae split 1,200  million years ago to 725  million years ago into two clades: chlorophytes and streptophytes . The chlorophytes, with around 700 genera, were originally marine algae, although some groups have since spread into fresh water . The streptophyte algae (i.e. excluding the land plants) have around 122 genera; they adapted to fresh water very early in their evolutionary history and have not spread back into marine environments. Some time during

416-752: The West of Scotland, Eire, parts of Wales and of the Lake District. Klebsormidium , the type of the Klebsormidiophyceae , is a simple filamentous form with circular, plate-like chloroplasts, reproducing by fragmentation, by dorsiventral, biciliate swarmers and, according to Wille, a twentieth-century algologist, by aplanospores . Sexual reproduction is simple and isogamous (the male and female gametes are outwardly indistinguishable). The Charales (Charophyceae), or stoneworts, are freshwater and brackish algae with slender green or grey stems;

448-478: The absence of phycobilins , the presence of chlorophyll a and chlorophyll b , cellulose in the cell wall and the use of starch , stored in the plastids, as a storage polysaccharide. The charophytes and embryophytes share several traits that distinguish them from the chlorophytes, such as the presence of certain enzymes (class I aldolase , Cu/Zn superoxide dismutase , glycolate oxidase , flagellar peroxidase ), lateral flagella (when present), and, in many species,

480-629: The base of charophytes (streptophytes). The cladograms below show consensus phylogenetic relationships based on plastid genomes and a new proposal for a third phylum of green plants based on analysis of nuclear genomes. Chlorophyta Mesostigmatophyceae s.l. Klebsormidiophyceae Charophyceae Coleochaetophyceae Zygnematophyceae Embryophytes (land plants) Palmophyllophyceae Prasinodermophyceae Chlorophyta Mesostigmatophyceae s.l. Klebsormidiophyceae Charophyceae Coleochaetophyceae Zygnematophyceae Embryophytes (land plants) Mesostigmatophyceae s.l. in

512-524: The cladograms corresponds to a clade of a narrower circumscription, Mesostigmatophyceae s.s., and a separate class Chlorokybophyceae, as used by AlgaeBase . The Mesostigmatophyceae are not filamentous, but the other basal charophytes (streptophytes) are. Embryophyta Traditional groups: The embryophytes ( / ˈ ɛ m b r i ə ˌ f aɪ t s / ) are a clade of plants , also known as Embryophyta ( / ˌ ɛ m b r i ˈ ɒ f ə t ə , - oʊ ˈ f aɪ t ə / ) or land plants . They are

544-769: The class Zygnematophyceae as a sister group . With the Embryophyta now cladistically placed in the Charophyte, it is a synonym of Streptophyta. The sister group of the charophytes are the Chlorophyta . In some charophyte groups, such as the Zygnematophyceae or conjugating green algae, flagella are absent and sexual reproduction does not involve free-swimming flagellate sperm. Flagellate sperm, however, are found in stoneworts ( Charales ) and Coleochaetales , orders of parenchymatous charophytes that are

576-606: The closest relatives of the land plants, where flagellate sperm are also present in all except the conifers and flowering plants . Fossil stoneworts of early Devonian age that are similar to those of the present day have been described from the Rhynie chert of Scotland. Somewhat different charophytes have also been collected from the Late Devonian (Famennian) Waterloo Farm lagerstätte of South Africa. These include two species each of Octochara and Hexachara , which are

608-463: The corresponding organs in other algae. As a result of fertilization, a protonema is formed, from which the sexually reproducing algae develops. A new terrestrial genus found in sandy soil in the Czech Republic , Streptofilum , may belong in its own class due its unique phylogenetic position. A cell wall is absent, instead the cell membrane consists of many layers of specific scales. It

640-569: The development of a septum between the two cell-halves or semi-cells (in unicellular forms, each daughter-cell develops the other semi-cell afresh) and sexually by conjugation, or the fusion of the entire cell-contents of the two conjugating cells. The saccoderm desmids and the placoderm or true desmids, unicellular or filamentous members of the Zygnematophyceae, are dominant in non-calcareous, acid waters of oligotrophic or primitive lakes (e.g. Wastwater), or in lochans, tarns and bogs, as in

672-878: The epiphyte flora in rain forest habitats. Protonema Moss spores germinate to form an alga -like filamentous structure called the protonema. It represents the juvenile gametophyte . While the protonema is growing by apical cell division, at some stage, under the influence of the phytohormone cytokinin , buds are induced which grow by three-faced apical cells. These give rise to gametophores , stems and leaf like structures. Bryophytes do not have true leaves ( megaphylls ). Protonemata are characteristic of all mosses and some liverworts but are absent from hornworts. Protonemata of mosses are composed of two cell types: chloronemata , which form upon germination, and caulonemata , which later differentiate from chloronemata and on which buds are formed, which then differentiate to gametophores . This plant morphology article

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704-425: The grey colour of many species results from the deposition of lime on the walls, masking the green colour of the chlorophyll. The main stems are slender and branch occasionally. Lateral branchlets occur in whorls at regular intervals up the stem, they are attached by rhizoids to the substrate. The reproductive organs consist of antheridia and oogonia , though the structures of these organs differ considerably from

736-465: The groups making up the embryophytes are related as shown in the cladogram below (based on Qiu et al. 2006 with additional names from Crane et al. 2004). Liverworts [REDACTED] Mosses [REDACTED] Hornworts [REDACTED] Lycophytes [REDACTED] ( ferns and horsetails ) [REDACTED] Angiosperms ( flowering plants ) [REDACTED] Gymnosperms [REDACTED] An updated phylogeny of Embryophytes based on

768-466: The land plants in the streptophyte lineage, some species within their relatives Coleochaetales , Charales and Zygnematales , as well as within subaerial species of the algae order Trentepohliales , and appears to be essential in the adaptation towards a terrestrial life style. The green algae and land plants form a clade , the Viridiplantae . According to molecular clock estimates,

800-909: The most familiar group of photoautotrophs that make up the vegetation on Earth 's dry lands and wetlands . Embryophytes have a common ancestor with green algae , having emerged within the Phragmoplastophyta clade of freshwater charophyte green algae as a sister taxon of Charophyceae , Coleochaetophyceae and Zygnematophyceae . Embryophytes consist of the bryophytes and the polysporangiophytes . Living embryophytes include hornworts , liverworts , mosses , lycophytes , ferns , gymnosperms and angiosperms ( flowering plants ). Embryophytes have diplobiontic life cycles . The embryophytes are informally called "land plants" because they thrive primarily in terrestrial habitats (despite some members having evolved secondarily to live once again in semiaquatic / aquatic habitats ), while

832-665: The oldest fossils of Charophyte axes bearing in situ oogonia . The name comes from the genus Chara , but the finding that the Embryophyta actually emerged in them has not resulted in a much more restricted meaning of the Charophyta, namely to a much smaller side branch. This more restricted group corresponds to the Charophyceae . The Zygnematophyceae , formerly known as the Conjugatophyceae, generally possess two fairly elaborate chloroplasts in each cell, rather than many discoid ones. They reproduce asexually by

864-437: The ovum takes place within the archegonium rather than in the external environment. Secondly, the initial stage of development of the fertilized egg (the zygote ) into a diploid multicellular sporophyte, takes place within the archegonium where it is both protected and provided with nutrition. This second feature is the origin of the term 'embryophyte' – the fertilized egg develops into a protected embryo, rather than dispersing as

896-450: The related green algae are primarily aquatic. Embryophytes are complex multicellular eukaryotes with specialized reproductive organs . The name derives from their innovative characteristic of nurturing the young embryo sporophyte during the early stages of its multicellular development within the tissues of the parent gametophyte . With very few exceptions, embryophytes obtain biological energy by photosynthesis , using chlorophyll

928-405: The same for each cell. The whole organism is thus constructed from similar, repeating parts or metamers . Accordingly, these plants are sometimes termed 'metaphytes' and classified as the group Metaphyta (but Haeckel 's definition of Metaphyta places some algae in this group ). In all land plants a disc-like structure called a phragmoplast forms where the cell will divide , a trait only found in

960-644: The use of phragmoplasts in mitosis . Thus Charophyta and Embryophyta together form the clade Streptophyta , excluding the Chlorophyta. Charophytes such as Palaeonitella cranii and possibly the yet unassigned Parka decipiens are present in the fossil record of the Devonian . Palaeonitella differed little from some present-day stoneworts. There is an emerging consensus on green algal relationships, mainly based on molecular data. The Mesostigmatophyceae (including Spirotaenia , and Chlorokybophyceae) are at

992-980: The work by Novíkov & Barabaš-Krasni 2015 and Hao and Xue 2013 with plant taxon authors from Anderson, Anderson & Cleal 2007 and some additional clade names. Puttick et al./Nishiyama et al. are used for the basal clades. Anthocerotophytina (Hornworts) Bryophytina (Mosses) Marchantiophytina (Liverworts) † Horneophytopsida [Protracheophytes] † Cooksoniaceae † Aglaophyton † Rhyniopsida † Catenalis † Aberlemnia † Hsuaceae † Renaliaceae † Adoketophyton †? Barinophytopsida † Zosterophyllopsida † Hicklingia † Gumuia † Nothia Lycopodiopsida (Clubmosses, Spikemosses & Quillworts) † Zosterophyllum deciduum † Yunia † Eophyllophyton † Trimerophytopsida † Ibyka † Pauthecophyton † Cladoxylopsida Polypodiopsida (ferns) † Celatheca † Pertica † Progymnosperms (paraphyletic) Spermatophytes (seed plants) The non-vascular land plants, namely

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1024-417: The zygote. In at least one species, it receives nourishment from the gametophyte through placental transfer cells. Charophyta are complex green algae that form a sister group to the Chlorophyta and within which the Embryophyta emerged. The chlorophyte and charophyte green algae and the embryophytes or land plants form a clade called the green plants or Viridiplantae , that is united among other things by

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