Liverworts Fossil range: Upper Devonian to recent
"Hepaticae" from Ernst Haeckel's Kunstformen der Natur, 1904
Scientific classification
Kingdom: Plantae Division: Marchantiophyta Stotler & Stotl.-Crand., 1977 emend. 2000
Classes and Orders
Jungermanniopsida Stotler & Stotl.-Crand., 1977 For the Celtic language, see Southwestern Brythonic language; for the residents of the English county, see Devon. ... Image File history File links Size of this preview: 428 × 600 pixelsFull resolution (2378 × 3331 pixel, file size: 1. ... Ernst Haeckel. ... The 8th print, Discomedusae. ... Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. ... For other uses, see Plant (disambiguation). ... Metzgeriales (simple thalloids) Haplomitriales (Calobryales) Jungermanniales (leafy liverworts) Marchantiopsida Stotler & Stotl.-Crand., 1977 Families See text. ... Genera Haplomitrium Haplomitriales is an order of plants known as Liverworts. ... Families See text Jungermanniales is the largest order of Liverworts. ... Sphaerocarpales (bottle liverworts) Marchantiales (complex thalloids) Monocleales

The Marchantiophyta [mɑː(r)ˈkæntiɑːfɪtə] (help·info) are a division of bryophyte plants commonly referred to as hepatics or liverworts. Like other bryophytes, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information. Families Riellaceae Sphaerocarpaceae Monocarpaceae Sphaerocarpales is an order of plants known as liverworts. ... Genera Conocephalum Lunularia Preissia Marchantia Riccia Ricciocarpus Marchantiales is an order of thallose liverworts that includes species like Lunularia cruciata, a common and often troubleseome weed in moist, temperate gardens and greenhouses. ... Genera Monoclea Monocleales is an order of plants known as Liverworts. ... The bryophytes are those embryophytes (land plants) that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. ... For other uses, see Plant (disambiguation). ...

It is estimated that there are 6000 to 8000 species of liverworts. Some of the more familiar species grow as a flattened leafless thallus, but most species are leafy with a form very much like a flattened moss. Leafy species can most reliably be distinguished from the apparently similar mosses by their single-celled rhizoids. Other differences are not universal for all mosses and all liverworts, but the occurrence of leaves arranged in three ranks, the presence of deep lobes or segmented leaves, or a lack of clearly differentiated stem and leaves all point to the plant being a liverwort. Thallus is an undifferentiated vegetative tissue (without specialization of function) of some non-mobile organisms, which were previously known as the thallophytes. ... For other uses, see Moss (disambiguation). ... Rhizoids, in fungi, are small branching hyphae that grow downwards from the stolons that anchor the fungus. ...

Liverworts are typically small, usually from 2-20 mm wide with individual plants less than 10 cm long, and are therefore often overlooked. However, certain species may cover large patches of ground, rocks, trees or any other reasonably firm substrate on which they occur. They are distributed globally in almost every available habitat, most often in humid locations although there are desert and arctic species as well. Some species can be a nuisance in shady green-houses.

Physical characteristics

Description

Most liverworts are typically small, usually from 2-20 mm wide with individual plants less than 10 cm long;^[1] they are therefore often overlooked. The most familiar liverworts consist of a prostrate, flattened, ribbon-like or branching structure called a thallus (plant body); these liverworts are termed thallose liverworts. However, most liverworts produce flattened stems with overlapping scales or leaves in three or more ranks, the middle rank being conspicously different from the outer ranks; these are called leafy liverworts or scale liverworts.^[2][3] (See the gallery below for examples.) Thallus is an undifferentiated vegetative tissue (without specialization of function) of some non-mobile organisms, which were previously known as the thallophytes. ... Families See text Jungermanniales is the largest order of Liverworts. ...

A thallose liverwort, Lunularia cruciata

Liverworts can most reliably be distinguished from the apparently similar mosses by their single celled rhizoids.^[4] Other differences are not universal for all mosses and all liverworts,^[3] but the lack of clearly differentiated stem and leaves in thallose species, or in leafy species the presence of deeply lobed or segmented leaves, and the presence of leaves arranged in three ranks all point to the plant being a liverwort.^[5][6] In addition, 90% of liverworts contain oil bodies in at least some of their cells, and these cellular structures are absent from most other bryophytes and from all vascular plants.^[7] However, the overall physical similarity of some mosses and leafy liverworts means that confirmation of the identification of some groups can only be performed with certainty with the aid of microscopy or an experienced bryologist. Download high resolution version (1644x1242, 733 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1644x1242, 733 KB) Wikipedia does not have an article with this exact name. ... Genera Conocephalum Lunularia Preissia Marchantia Riccia Ricciocarpus Marchantiales is an order of thallose liverworts that includes species like Lunularia cruciata, a common and often troubleseome weed in moist, temperate gardens and greenhouses. ... For other uses, see Moss (disambiguation). ... Rhizoids, in fungi, are small branching hyphae that grow downwards from the stolons that anchor the fungus. ... This article or section is not written in the formal tone expected of an encyclopedia article. ...

Liverworts have a gametophyte-dominant life cycle, with the sporophyte dependent on the gametophyte.^[7] That is, the plant's cells are haploid for the majority of its life cycle. Cells in a typical liverwort plant each contain only a single set of genetic information. This contrasts sharply with the pattern exhibited by nearly all animals and by most other plants. In the more familiar seed plants, the haploid generation is represented only by the tiny pollen and the ovule, whilst the diploid generation is the familiar tree or other plant.^[8] Another unusual feature of the liverwort life cycle is that sporophytes (i.e. the diploid body) are very short-lived, withering away not long after it releases its spores.^[9] Even in other bryophytes, the sporophyte is long persistent and disperses spores over an extended period. In plants that undergo alternation of generations, a gametophyte is the structure, or phase of life, that contains only half of the total complement of chromosomes: The sporophyte produces spores, in a process called meiosis. ... In plants that undergo alternation of generations, a sporophyte is the structure, or phase of life, that contains a total complement of chromosomes: The sporophyte produces spores, in a process called meiosis. ... Haploid (meaning simple in Greek) cells have only one copy of each chromosome. ... The spermatophytes comprise those plants that produce seeds. ... SEM image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis). ... This article or section does not adequately cite its references or sources. ... Diploid (meaning double in Greek) cells have two copies (homologs) of each chromosome (both sex- and non-sex determining chromosomes), usually one from the mother and one from the father. ... Diploid (meaning double in Greek) cells have two copies (homologs) of each chromosome (both sex- and non-sex determining chromosomes), usually one from the mother and one from the father. ... The bryophytes are those embryophytes (land plants) that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. ...

Life cycle

Life cycle of a typical liverwort

The life of a liverwort starts from the germination of a haploid spore to produce a protonema, which is either a mass of thread-like filaments or else a flattened thallus.^[10][11] The protonema is a transitory stage in the life of a liverwort, from which will grow the mature gametophore ("gamete-bearer") plant that produces the sex organs. The male organs are known as antheridia (singular: antheridium) and produce the sperm cells. Clusters of antheridia are enclosed by a protective layer of cells called the perigonium (plural: perigonia). As in other land plants, the female organs are known as archegonia (singular: archegonium) and are protected by the thin surrounding perichaetum (plural: perichaeta).^[3] Each archegonium has a slender hollow tube, the "neck", down which the sperm swim to reach the egg cell. Image File history File links Download high resolution version (1222x1239, 384 KB) Diagram of the life cycle of a tipical liverwort (Bryophyte) the diagram i did myself with adobe illustrator based on the diagrams found on this webpages:[1],[2], [3],[4],[5]. the diagram was finished one the 16... Image File history File links Download high resolution version (1222x1239, 384 KB) Diagram of the life cycle of a tipical liverwort (Bryophyte) the diagram i did myself with adobe illustrator based on the diagrams found on this webpages:[1],[2], [3],[4],[5]. the diagram was finished one the 16... This article or section is in need of attention from an expert on the subject. ... A protonema (plural: protonemata) is a thread-like chain of cells that forms the earliest stage (the haploid phase) of a bryophyte life cycle. ... A gamete is a specialized germ cell that fuses with another gamete during fertilization (conception) in organisms that reproduce sexually. ... Diagram of antheridium anatomy An antheridium (plural: antheridia) is a structure or organ of the gametophyte phase of certain plants producing and containing the spermatids or male gametes. ... An archegonium (pl: archegonia) (from the Greek arche = beginning and gonos = born) is a multicellular structure or organ of the gametophyte phase of certain plants producing and containing the ovum or female gamete. ...

Liverwort species may be either dioicous or monoicous. In dioicious liverworts, female and male sex organs are borne on different and separate gametophyte plants. In monoicious liverworts, the two kinds of reproductive structures are borne on different branches of the same plant.^[12] In either case, the sperm must swim from the antheridia where they are produced to the archegonium where the eggs are held. The sperm of liverworts is biflagellate, i.e. they have two tail-like flagellae that aid in propulsion.^[13] Their journey is further assisted either by the splashing of raindrops or the presence of a thin layer of water covering the plants. Without water, the journey from antheridium to archegonium cannot occur. The bryophytes are those embryophytes (land plants) that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. ... The bryophytes are those embryophytes (land plants) that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. ... For other uses, see Sperm (disambiguation). ... // A flagellum (plural: flagella) is a long, slender projection from the cell body, composed of microtubules and surrounded by the plasma membrane. ...

In the presence of such water, sperm from the antheridia swim to the archegonia and fertilisation occurs, leading to the production of a diploid sporophyte. After fertilisation, the immature sporophyte within the archegonium develops three distinct regions: (1) a foot, which both anchors the sporophyte in place and receives nutrients from its "mother" plant, (2) a spherical or ellipsoidal capsule, inside which the spores will be produced for dispersing to new locations, and (3) a seta (stalk) which lies between the other two regions and connects them.^[13] When the sporophyte has developed all three regions, the seta elongates, pushing its way out of the archegonium and rupturing it. While the foot remains anchored within the parent plant, the capsule is forced out by the seta and is extended away from the plant and into the air. Within the capsule, cells divide to produce both elater cells and spore-producing cells. The elaters are spring-like, and will push open the wall of the capsule to scatter themselves when the capsule bursts. The spore-producing cells will undergo meiosis to form haploid spores to disperse, upon which point the life cycle can start again. A sperm cell fertilizing an ovum This article is about reproduction in organisms. ... In plants that undergo alternation of generations, a sporophyte is the structure, or phase of life, that contains a total complement of chromosomes: The sporophyte produces spores, in a process called meiosis. ... An elater is a cell (or structure attached to a cell) that is hygroscopic, and therefore will change shape in response to changes in moisture in the environment. ... Not to be confused with miosis. ... This article or section is in need of attention from an expert on the subject. ...

Ecology

Today, liverworts can be found in many ecosystems across the planet except the sea and excessively dry environments, or those exposed to high levels of direct solar radiation.^[14] As with most groups of living plants, they are most common (both in numbers and species) in moist tropical areas.^[15] Liverworts are more commonly found in moderate to deep shade, though desert species may tolerate direct sunlight and periods of total dessication.

Classification

Relationship to other plants

Traditionally, the liverworts were grouped together with other bryophytes (mosses and hornworts) in the Division Bryophyta, within which the liverworts made up the class Hepaticae (also called Marchantiopsida).^[16][3] However, since this grouping makes the Bryophyta paraphyletic, the liverworts are now usually given their own division.^[17] The use of the division name Bryophyta sensu latu is still found in the literature, but more frequently the Bryophyta now is used in a restricted sense to include only the mosses. The bryophytes are those embryophytes (land plants) that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. ... For other uses, see Moss (disambiguation). ... Families & Genera Anthocerotaceae Anthoceros Folioceros Leiosporoceros Phaeoceros Sphaerosporoceros Dendrocerotaceae Dendroceros Megaceros Notoceros Notothyladaceae Notothylas Hornworts are a group of bryophytes, or non-vascular plants, comprising the division Anthocerotophyta. ... Paraphyletic - Wikipedia /**/ @import /skins-1. ... Subclasses Andreaeidae Sphagnidae Tetraphidae Polytrichidae Buxbaumiidae Bryidae Archidiidae Moss on a rock Mosses belong to the non-vascular plants. ...

Another reason that liverworts are now classified separately is that liverworts appear to have diverged from all other embryophyte plants near the beginning of their evolution. The strongest line of supporting evidence is that liverworts are the only living group of land plants that do not have stomata on the sporophyte generation.^[18] The earliest fossils believed to be liverworts are compression fossils of Pallaviciniites from the Upper Devonian of New York.^[19] These fossils resemble modern species in the Metzgeriales.^[20] Another Devonian fossil called Protosalvinia also looks like a liverwort, but its relationship to other plants is still uncertain, so it may not belong to the Marchantiophyta. Image File history File links Bryo_cladogram. ... Divisions Non-vascular land plants (bryophytes) Marchantiophyta - liverworts Anthocerotophyta - hornworts Bryophyta - mosses †Horneophytopsida Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta - ferns and horsetails Ophioglossophyta - adders-tongues Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants The embryophytes... This article is about evolution in biology. ... Stoma of a leaf under a microscope. ... In plants that undergo alternation of generations, a sporophyte is the structure, or phase of life, that contains a total complement of chromosomes: The sporophyte produces spores, in a process called meiosis. ... For other uses, see Fossil (disambiguation). ... A compression fossil is a fossil preserved in sedimentary rock that has undergone physical compression. ... For the Celtic language, see Southwestern Brythonic language; for the residents of the English county, see Devon. ... “NY” redirects here. ... Families See text. ... Species Protosalvinia arnoldii † Protosalvinia braziliensis † Protosalvinia furcata † Protosalvinia ravenna † Protosalvinia is a prehistoric plant found commonly in shale from shoreline habitats of the Upper Devonian period. ...

Internal classification

Bryologists classify liverworts in the division Marchantiophyta. This divisional name is based on the name of the most universally recognized liverwort genus Marchantia.^[21] In addition to this taxon-based name, the liverworts are often called Hepaticophyta. This name is derived from their common Latin name as Latin was the language in which botanists published their descriptions of species. This name has led to some confusion, partly because it appears to be a taxon-based name derived from the genus Hepatica which is actually a flowering plant of the buttercup family Ranunculaceae. In addition, the name Hepaticophyta is frequently misspelled in textbooks as Hepatophyta, which only adds to the confusion. Bryologie is the branch of botany concerned with the scientific study of mosses. ... Species See text. ... A taxon (plural taxa), or taxonomic unit, is a grouping of organisms (named or unnamed). ... For other uses, see Genus (disambiguation). ... Species Hepatica acutiloba Hepatica americana Hepatica nobilis Hepatica transsilvanica Hepatica is a genus of herbaceous perennial plants belonging to the buttercup family, Ranunculaceae. ... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants or angiosperms are the most widespread group of land plants. ... genera see text Ranunculaceae is the botanical name for a family of flowering plants. ...

The Marchantiophyta is subdivided into two classes. The Jungermanniopsida includes primarily the two orders Metzgeriales (simple thalloids) and Jungermanniales (leafy liverworts), as well as a smaller order Haplomitriales. The Marchantiopsida includes primarily the orders Marchantiales (complex-thallus liverworts) and Sphaerocarpales (bottle hepatics), as well as the problematic genus Monoclea, which is sometimes placed in its own order Monocleales.^[22] In scientific classification used in biology, the order (Latin: ordo, plural ordines) is a rank between class and family (termed a taxon at that rank). ... Families See text. ... Families See text Jungermanniales is the largest order of Liverworts. ... Genera Haplomitrium Haplomitriales is an order of plants known as Liverworts. ... Genera Conocephalum Lunularia Preissia Marchantia Riccia Ricciocarpus Marchantiales is an order of thallose liverworts that includes species like Lunularia cruciata, a common and often troubleseome weed in moist, temperate gardens and greenhouses. ... Families Riellaceae Sphaerocarpaceae Monocarpaceae Sphaerocarpales is an order of plants known as liverworts. ... Species Monoclea forsteri Monoclea gottschei Monoclea is a genus of two species, of liverworts. ...

It is estimated that there are 6000 to 8000 species of liverworts, at least 85% of which belong to the leafy group.^[23]

Economic importance

In ancient times, it was believed that liverworts cured diseases of the liver, hence the name.^[24] In Old English, the word liverwort literally means liver plant.^[25] This probably stemmed from the superficial appearance of some thalloid liverworts (which resemble a liver in outline), and led to the common name of the group as hepatics, from the Latin word hēpaticus for "belonging to the liver". An unrelated flowering plant, Hepatica, is sometimes also referred to as liverwort because it was once also used in treating diseases of the liver. This archaic relationship of plant form to function was based in the "Doctrine of Signatures".^[26] The liver is an organ present in vertebrates and some other animals. ... Old English (also called Anglo-Saxon[1], Old English: ) is an early form of the English language that was spoken in parts of what is now England and southern Scotland between the mid-fifth century and the mid-twelfth century. ... For other uses, see Latin (disambiguation). ... Species Hepatica acutiloba Hepatica americana Hepatica nobilis Hepatica transsilvanica Hepatica is a genus of herbaceous perennial plants belonging to the buttercup family, Ranunculaceae. ... The doctrine of signatures refers to two separate concepts. ...

Liverworts have little direct economic importance today. Their greatest impact is indirect, though the reduction of erosion along streambanks, their collection and retention of water in tropical forests, and the formation of soil crusts in deserts and polar regions. However, a few species are used by humans directly. The species Riccia fluitans and Monosolenium tenerum are aquatic thallose liverworts sold for use in aquaria. Their thin, slender branches float on the water's surface and provide habitat for both small invertebrates and the fish that feed on them. In more arid regions, vegetative cover is generally sparse. ... Binomial name Riccia fluitans Riccia fluitans whose common name is crystalwort is an aquatic floating plant of the liverwort family which is popular among aquarists as a retreat for young fry and is used in live-bearing tanks. ... “Aquaria” redirects here. ...

Media

A small collection of images showing liverwort structure and diversity:

Marchantia polymorpha, with antheridial and archegonial stalks.	The archegonium of Porella.	A sporophyte emerging from its archegonium.	Porella platyphylla clump growing on a tree.
Pellia epiphylla, growing on moist soil.	Plagiochila asplenoides, a leafy liverwort.	Riccia fluitans, an aquatic thallose liverwort.	Conocephalum conicum, a large thallose liverwort.

Species See text. ... An archegonium (pl: archegonia) (from the Greek arche = beginning and gonos = born) is a multicellular structure or organ of the gametophyte phase of certain plants producing and containing the ovum or female gamete. ... Families See text Jungermanniales is the largest order of Liverworts. ... Binomial name Riccia fluitans Riccia fluitans whose common name is crystalwort is an aquatic floating plant of the liverwort family which is popular among aquarists as a retreat for young fry and is used in live-bearing tanks. ... Genera Conocephalum Lunularia Preissia Marchantia Riccia Ricciocarpus Marchantiales is an order of thallose liverworts that includes species like Lunularia cruciata, a common and often troubleseome weed in moist, temperate gardens and greenhouses. ... A horned liverwort (Anthocerotae) photographed on the Island of Hawaii by Eric Guinther and released under the GNU Free Documentation License. ...

See also

• Bryophyte
• Embryophyte

The bryophytes are those embryophytes (land plants) that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. ... Divisions Non-vascular land plants (bryophytes) Marchantiophyta - liverworts Anthocerotophyta - hornworts Bryophyta - mosses †Horneophytopsida Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta - ferns and horsetails Ophioglossophyta - adders-tongues Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants The embryophytes...

References

External links

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Category:Marchantiophyta

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Marchantiophyta

Look up liverwort in
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• Picture Gallery of Mosses & Liverworts
• Liverwort structure in pictures
• Liverwort classification scheme
• LiToL: Assembling the Liverwort Tree of Life (note: for 500,000 million years ago read "480 million years ago".)
• Inter-relationships of Mosses, Liverworts, and Hornworts
• Moss-Liverwort connection
• Additional information on Liverworts
• Liverworts