? Liverwort
A thallose liverwort, Lunularia cruciata
Scientific classification
Kingdom: Plantae Division: Hepaticophyta Class: Hepaticopsida
Orders
Haplomitriales Sphaerocarpales Marchantiales Metzgeriales Monocleales Jungermanniales Takakiales Download high resolution version (1644x1242, 733 KB) Wikipedia does not have an article with this exact name. ... Genera Conocephalum Lunularia Pressia Marchantia Riccia Ricciocarpus Marchantiales is an order of thallose liverworts which includes the species Lunularia cruciata, a common and often troubleseome weed in moist temperate gardens and greenhouses. ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Divisions Land plants (embryophytes) Non-vascular plants (bryophytes) Hepatophyta - liverworts Anthocerophyta - hornworts Bryophyta - mosses Vascular plants (tracheophytes) Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongues Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants Adiantum pedatum (a fern... Haplomitriales is an order of plants known as Liverworts. ... Sphaerocarpales is an order of plants known as liverworts. ... Genera Conocephalum Lunularia Pressia Marchantia Riccia Ricciocarpus Marchantiales is an order of thallose liverworts which includes the species Lunularia cruciata, a common and often troubleseome weed in moist temperate gardens and greenhouses. ... Metzgeriales is an order of Liverworts. ... Monocleales is an order of plants known as Liverworts. ... Jungermanniales is the largest order of Liverworts. ... Takakiales is an order of plants. ...

Liverworts are non-vascular plants, also called hepatics (scientific name Hepaticophyta). Originally such plants were grouped together as the Division Bryophyta, within which the liverworts made up the class Marchantiopsida (also called Hepaticae). However, since this makes the Bryophyta paraphyletic, the liverworts are now usually given their own division, Hepaticophyta, with a single class, Hepaticopsida. Liverworts appear to have diverged from all other embryophyte plants near the beginning of their evolution. Divisions Simple nonvascular plants     Green algae Complex nonvascular plants     Bryophyta - mosses     Hepatophyta - liverworts     Anthocerophyta - hornworts Non-vascular plants are plants that lack water-conducting vessels in their tissue known as tracheids. ... Paraphyletic - Wikipedia /**/ @import /skins-1. ... The embryophytes are the most familiar group of plants, including trees, flowers, ferns, mosses, and various others. ...

Liverworts can be found in almost all ecosystems across the planet except the sea and particularly inhospitable terrestial ecosystems (desert, permanent ice etc.) They are most common, both in numbers and species, in moist tropical areas.

The most familiar liverworts consist of a prostrate, flattened, 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. Thallus is an undifferentiated vegetative tissue (without specialization of function) of some non-mobile organisms, which were previously known as the thallophytes. ...

They can 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 lack of clearly differentiated stem and leaves, 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. Confirmation of the identifiaction of a moss or a leafy liverwort can only be performed with certainty by microscopical investigation. Subclasses Andreaeidae Sphagnidae Tetraphidae Polytrichidae Buxbaumiidae Bryidae Archidiidae Moss on a rock Mosses are a type of simple or non-vascular plant. ... Rhizoids, in fungi, are small branching hyphae that grow downwards from the stolons that anchor the fungus. ... 1852 microscope Compound microscope made by John Cuff in 1750 A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. ...

Aside from lacking a vascular system, liverworts have a gametophyte-dominant life cycle, i.e. the plant's cells are haploid for most of its life cycle. Sporophytes (i.e. the diploid body) are short-lived and dependent on the gametophyte. This is in contrast to the pattern exhibited by most higher plants and animals. In higher plants, for example, the haploid generation is represented by the pollen and the ovule while the diplod generation is the familiar flowering plant. Divisions Non-seed-bearing plants Equisetophyta Lycopodiophyta Psilotophyta Pteridophyta Superdivision Spermatophyta Pinophyta Cycadophyta Ginkgophyta Gnetophyta Magnoliophyta The vascular plants are those plants that have specialized cells for conducting water and sap within their tissues, including the flowering plants, conifers and other gymnosperms, but not mosses, algae, and the like (nonvascular... A gametophyte is the haploid structure or phase of life of a sexually reproducing plant. ... A life cycle includes the major sexual stages of a species, especially in regard to its ploidy. ... Haploid (meaning simple in Greek) cells have only one copy of each chromosome. ... A sporophyte is the diploid structure or phase of life of a sexually reproducing plant. ... 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. ... SEM image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomea purpurea), hollyhock (Sildalcea malviflora), lily (Lilium auratum), primrose (Oenothera fruticosa), and castor bean (Ricinus communis). ... Structure found in seed plants that develops into a seed after fertilization. ...

Life cycle

Life cycle of a typical Liverwort

The life of a liverwort starts from a haploid spore, which germinates to produce a protonema, which is either a mass of filaments or thalloid (flat and thallus-like). This is a transitory stage in the life of a liverwort. From the protonema grows the gametophore ("gamete-bearer") that produces the sex organs of the liverworts. The female organs are known as archegonia (singular archegonium) and are protected by the perichaetum (plural perichaeta). The archegonia have necks called venters which the male sperm swim down. The male organs are known as antheridia (singular antheridium) and are enclosed by the perigonium (plural perigonia). The term spore have several different meanings in biology. ... 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. ... Antheridium (plural: antheridia) is a structure or organ of the gametophyte phase of certain plants producing and containing the sperm or male gametes. ...

Liverworts can be either dioecious or monoecious. In dioecious liverworts, male and female sex organs are borne on different plants. In monoecious liverworts, they are borne on the same plant. In the presence of water, sperm from the antheridia swim to the archegonia and fertilisation occurs, leading to the production of a diploid sporophyte. The sperm of liverworts is biflagellate, i.e. they have two flagellae that aid in propulsion. Without water, fertilisation cannot occur. After fertilisation, the immature sporophyte pushes its way out of the archegonial venter. It takes about a quarter to half a year for the sporophyte to mature. The sporophyte body comprises a long stalk, called a seta, and a capsule capped by a cap - the operculum. The capsule and operculum are in turn sheathed by a haploid calyptra which is the remains of the archegonial venter. The calyptra usually falls off when the capsule is mature. Within the capsule, spore-producing cells undergo meiosis to form haploid spores, upon which the cycle can start again. Plant sexuality deals with the wide variety of sexual reproduction systems found across the plant kingdom. ... Plant sexuality deals with the wide variety of sexual reproduction systems found across the plant kingdom. ... In Biology operculum (Latin for little lid) has been used to describe several completely separate features. ... In biology, meiosis is the process that transforms one diploid cell into four haploid cells in eukaryotes. ...

In ancient times, it was believed that liverworts cured diseases of the liver, hence the name. This probably stemed from the superficial appearance of some thalloid liverworts, which resemble a liver in outline. An unrelated flowering plant, Hepatica, is sometimes also refered to as liverwort because it was once also used in treating diseases of the liver. The liver is an organ in vertebrates, including humans. ... Species Hepatica acutiloba Hepatica americana Hepatica nobilis Hepatica transsilvanica Hepatica (Hepatica) is a genus of herbaceous perennial plants belonging to the buttercup family, Ranunculaceae. ...

References

• Bold, Alexopoulos, and Delevoryas, 1987, Morphology of Plants and Fungi, Harper-Collins, NY.

External links

• Additional information on Liverworts
• Liverworts
• Liverwort structure in pictures
• Moss-Liverwort connection
• Liverwort classification scheme
• Inter-relationships of Mosses, Liverworts, and Hornworts