52-398: Riccia is a genus of liverworts in the order Marchantiales . These plants are small and thalloid , i.e. not differentiated into root, stem and leaf. Depending on species, the thallus may be strap-shaped and about 0.5 to 4 mm wide with dichotomous branches or may form rosettes or hemirosettes up to 3 cm in diameter, that may be gregarious and form intricate mats. The thallus
104-412: A mutant of Marchantia polymorpha lacking oil-bodies was studied for palatability to herbivores, and it was found that a loss of the organelles was associated with far greater grazing by pill-bugs. In general, herbivore grazing on extant liverworts seems to be quite low, and this is likely not due to an un-worthwhile caloric content but the secondary metabolites likely stored in the oil bodies of
156-424: A protonema , which is either a mass of thread-like filaments or a flattened thallus. 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
208-597: A synapomorphy for the phylum , the ontogeny of complex oil bodies across liverworts remains uncertain. Uncertainty arises as to the conservation of development between the Marchantiopsida and Jungermanniopsida . Working with light and electron microscopy , the oil bodies of various Jungermanniopsida species were observed to be derived from dilations of endoplasmic reticulum cisternae . In certain Marchantiopsida species, again based upon light and electron microscopy, oil bodies were hypothesized to result from
260-684: A lack of clearly differentiated stem and leaves all point to the plant being a liverwort. Liverworts are distinguished from mosses in having unique complex oil bodies of high refractive index. Liverworts are typically small, usually from 2–20 mm (0.079–0.787 in) wide with individual plants less than 10 cm (3.9 in) 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
312-526: A monophyletic clade ("Bryophyta sensu lato " or "Bryophyta Schimp.") alongside mosses and hornworts. Hence, it has been suggested that the liverworts should be de-ranked to a class called Marchantiopsida. In addition, there is strong phylogenetic evidence to suggest that liverworts and mosses form a monophyletic subclade named Setaphyta . vascular plants hornworts mosses liverworts vascular plants hornworts mosses liverworts An important conclusion from these phylogenies
364-525: A nuisance in shady greenhouses or a weed in gardens. Most liverworts are small, measuring from 2–20 millimetres (0.08–0.8 in) wide with individual plants less than 10 centimetres (4 in) long, so they are 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 two or more ranks,
416-415: A number of features, including their single-celled rhizoids . Leafy liverworts also differ from most (but not all) mosses in that their leaves never have a costa (present in many mosses) and may bear marginal cilia (very rare in mosses). Other differences are not universal for all mosses and liverworts, but the occurrence of leaves arranged in three ranks, the presence of deep lobes or segmented leaves, or
468-1128: 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. Although there is no consensus among bryologists as to the classification of liverworts above family rank, the Marchantiophyta may be subdivided into three classes: Haplomitriales Treubiales Blasiales Marchantiales Sphaerocarpales Metzgeriales (part) Metzgeriales (part) Jungermanniales Haplomitriales Treubiales Blasiales Neohodgsoniales Sphaerocarpales Lunulariales Marchantiales Pelliales Fossombroniales Pallaviciniales Metzgeriales Pleuroziales Jungermanniales Porellales Ptilidiales An updated classification by Söderström et al. 2016 Complex oil bodies The oil bodies of liverworts , occasionally dubbed complex oil bodies for distinction, are unique organelles exclusive to
520-400: A typical liverwort plant each contain only a single set of genetic information, so the plant's cells are haploid for the majority of its life cycle. This contrasts sharply with the pattern exhibited by nearly all animals and by vascular plants. In the more familiar seed plants , the haploid generation is represented only by the tiny pollen and the ovule , while the diploid generation is
572-456: A variety of ailments including cuts, burns and bruises, pulmonary tuberculosis , convulsions and neurasthenia . Pellia neesiana has been used in a traditional medicine by Hesquiat people for children's sore mouths, and Conocephalum salebrosum has been used as an eye medicine by the Ditidaht . Various liverworts have been incorporated by Maori in traditional medicine. Although
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#1732780986489624-413: Is dorsiventrally differentiated. Its upper (dorsal) surface is green and chlorophyll -bearing, with a mid-dorsal longitudinal sulcus (furrow or groove). Air pores occasionally break through the dorsal surface, giving the thallus a dimpled appearance. In exceptional members such as Riccia caroliniana of Northern Australia and Riccia sahyadrica of Western Ghats, the photosynthetic region is confined to
676-544: Is not consistent; While Blasia pusilla lacks both oil bodies and terpenoids , Anthelia julacea lacks oil bodies but retains terpenoids and aromatic compounds. Although present in some species lacking complex oil bodies, the association with terpenoids is furthered by evidence based upon enzyme localization in Marchantia polymorpha indicating that oil bodies are sites of isoprenoid synthesis in liverworts. The localization of sesquiterpenes and Marchantin A to
728-515: Is often lacking, however many of these theories have been supported in one way or another. Worth noting is that the modern adaptive function of complex oil bodies may be diverse across the phylum and inconsistent between species. For example, it was found that oil bodies in Southbya nigrella likely served a role is desiccation-tolerance, however xeric Riccia species and highly exposed Anthelia have no oil bodies at all. In Southbya nigrella ,
780-500: Is sometimes used in aquariums . Plants are usually monoicous , and sexual reproduction is by antheridia and archegonia . Asexual reproduction occurs by spores , by fragmentation of the rosettes, and by formation of apical tubers . Spores are large (45 to 200 μ ) and formed in tetrads. The sporophyte of Riccia is the simplest amongst bryophytes . It consist of only a capsule, missing both foot and seta, and does not perform photosynthesis. The following species are recognised in
832-575: Is still uncertain, so it may not belong to the Marchantiophyta. In 2007, the oldest fossils assignable at that time to the liverworts were announced, Metzgeriothallus sharonae from the Givetian (Middle Devonian ) of New York , United States. However, in 2010, five different types of fossilized liverwort spores were found in Argentina, dating to the much earlier Middle Ordovician , around 470 million years ago. Bryologists classify liverworts in
884-529: Is that the ancestral stomata appear to have been lost in the liverwort lineage. Among the earliest fossils believed to be liverworts are compression fossils of Pallaviciniites from the Upper Devonian of New York . These fossils resemble modern species in the Metzgeriales . Another Devonian fossil called Protosalvinia also looks like a liverwort, but its relationship to other plants
936-530: The Jungermanniopsida and Haplomitriales , and restricted to specialized oil-cells sometimes denoted as ocelli in the Marchantiopsida and Treubiales . Phylogenetic evidence does not indicate an evident ancestral form of the complex oil bodies as the basal Haplomitriopsida lineages Treubia and Haplomitrium display two different types of oil bodies. Limited fossil evidence has suggested that Paleozoic liverwort oil bodies are homologous to
988-521: The Late Silurian / Early Devonian . 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
1040-791: The Marchantiophyta . They are markedly different from the oil bodies found in other land plants and algae in that they are membrane-bound, and not associated with food storage. The organelles are variable and present in an estimated 90% of liverwort species, often proving taxonomically relevant. As a whole, the formation and function of the organelles are poorly understood. Complex oil bodies are recognized as sites of isoprenoid biosynthesis and essential oil accumulation, and have been implicated with anti-herbivory, desiccation tolerance, and photo-protection. The oil bodies of liverworts are recognizable using light microscopy , and they were first officially described in 1834 by Huebener from
1092-515: 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). Each archegonium has a slender hollow tube, the "neck", down which the sperm swim to reach the egg cell. Liverwort species may be either dioicous or monoicous . In dioicous liverworts, female and male sex organs are borne on different and separate gametophyte plants. In monoicous liverworts,
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#17327809864891144-555: The plasma membrane and oil body were hypothesized. Numerous functions for the organelles have been hypothesized, including that the organelles may be largely vestigial . Although lost in numerous taxa, the predominant retention and diversity of the organelles suggests an adaptive role, and their importance is quite evident. Theory over the years has implicated complex oil bodies with virtually all evident stressors, such as herbivore and pathogen damage, thermal stress, excessive light/UV irradiation, and desiccation. Empirical evidence
1196-475: 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. The sporophyte lacks an apical meristem , an auxin -sensitive point of divergence with other land plants some time in
1248-648: The complex oil bodies disintegrate. Worth noting is that under natural rates of desiccation the oil bodies seem to retain their original structure. Various classifications for oil body types have been proposed based upon their high variability, and they have been used extensively to distinguish between families, genera and species. Chemotaxonomics based on the putative oil-body contents has also proved valuable. Although some families such as Blasiaceae , Metzgeriaceae , Cephaloziaceae , Lepidoziaceae , and Antheliaceae lack complex oil bodies, they are broadly present in all mature gametophytic and sporophytic cells in
1300-550: The cytoplasm of all other plants being unenclosed. The overall physical similarity of some mosses and leafy liverworts means that confirmation of the identification of some groups can be performed with certainty only with the aid of microscopy or an experienced bryologist . Liverworts, like other bryophytes, have a gametophyte -dominant life cycle, with the sporophyte dependent on the gametophyte. The sporophyte of many liverworts are non-photosynthetic, but there are also several that are photosynthetic to various degrees. Cells in
1352-436: The division Marchantiophyta . This divisional name is based on the name of the most universally recognized liverwort genus Marchantia . 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
1404-553: The entire surface of containers; gemma dispersal is the "primary mechanism by which liverwort spreads throughout a nursery or greenhouse." Thalloid liverworts typically harbor symbiotic glomeromycete fungi which have arbuscular (cilia-bearing) rootlets resembling those in vascular plants. Species in the Aneuraceae , however, associate with basidiomycete fungi belonging to the genus Tulasnella , while leafy liverworts typically harbor symbiotic basidiomycete fungi belonging to
1456-411: The familiar tree or other plant. 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 releasing spores. In mosses, the sporophyte is more persistent and in hornworts, the sporophyte disperses spores over an extended period. The life of a liverwort starts from the germination of a haploid spore to produce
1508-478: The fungal invasion of liverworts in the family Arnelliaceae has been associated with a rapid breakdown of oil bodies. Complex oil bodies are often the most conspicuous features of liverwort cells in light microscopy, and as variable as they are in number, shape, colour, and homogeneity, they have long been recognized as taxonomically relevant. Unfortunately, this is a character that requires observation in fresh material, as under unnaturally high rates of drying
1560-428: The fusion of golgi -associated vesicles . When re-examined independently in Marchantia polymorpha and Lunularia cruciata , this hypothesis was refuted in favour of that which unifies the development of all liverwort oil bodies from ER cisternae. Recent molecular work in Marchantia polymorpha has however once again supported the fusion of vesicles, and oscillating phases of secretory pathway redirection to
1612-771: The genera Porella , Pellia , Pallavicini , Fossombronia and Trichocoleopsis . The secondary metabolites of liverworts offer an under-characterised diversity of potentially pharmaceutically relevant compounds. Liverwort terpenoids and lipophilic compounds have been observed to have significant biological activity, including cyto-toxicity , anti-obesity, anti- influenza , allergenic contact dermatitis , anti- HIV inhibitory, antimicrobial , and vasorelaxant effects. Compounds such as Marchantin and Riccardin as well as extracts from Bazzania and Scapania species have been shown to have pronounced antitumour effects. Indeed, liverworts have been used medicinally by humans for centuries. In China, liverworts have been used for
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1664-485: The genus Serendipita . 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. As with most groups of living plants, they are most common (both in numbers and species) in moist tropical areas. Liverworts are more commonly found in moderate to deep shade, though desert species may tolerate direct sunlight and periods of total desiccation. Traditionally,
1716-437: The genus Riccia : Marchantiophyta The Marchantiophyta ( / m ɑːr ˌ k æ n t i ˈ ɒ f ə t ə , - oʊ ˈ f aɪ t ə / ) are a division of non-vascular land plants commonly referred to as hepatics or liverworts . Like mosses and hornworts , they have a gametophyte -dominant life cycle, in which cells of the plant carry only a single set of genetic information. The division name
1768-828: The group. Monoterpenes are also present, and have been associated with the sometimes distinctive odours of some species. For example: Chiloscyphus species have been noted to have a strong mossy smell, Jungermannia , Frullania , and Geocalyx species smell of turpentine, and Lophozia vicernata is likened to cedar oil, Moerkia species are intensely unpleasant, Conocephalum species are pungent and mushroomy, Pellia endiviifolia shares qualities with dried seaweed, and Riella species with anise . Interestingly, it has been observed that most sesqui- and diterpenoids in liverworts are enantiomers of those found in vascular plants , although there are numerous only found in liverworts. Pinguisane- and sacculatane-type diterpenes are exclusively found in liverworts, detected in
1820-514: The hypothesis that oil-bodies can function as herbivore-deterrents. Fossil evidence of herbivore damage on the middle Devonian liverwort Metzgeriothallus sharonae suggests an already deterrent role of the oil-bodies, whereby cells presumed to be oil-cells were preferentially avoided. In an early feeding experiment using various liverworts and several species of snail , it was noted that liverworts leached by alcohol were far more palatable, with fresh liverworts often being seldom touched. Recently,
1872-517: 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). Somewhat more recently, the liverworts were given their own division (Marchantiophyta), as bryophytes became considered to be paraphyletic . However, the most recent phylogenetic evidence indicates that liverworts are indeed likely part of
1924-471: The localization of these compounds to complex oil bodies has not been confirmed. As liverworts are often considered the closest extant relative of one of the earliest groups of land plants, they would likely have been required to be adapted to the harsh conditions of a thinner ozone layer , thus the development of these UV-shielding compounds may reflect a key development in the evolution of land plants. Studies on herbivore grazing are few but supportive of
1976-433: The lower half of the thallus. The lower (ventral) surface has a mid-ventral ridge bearing multicellular scales that originate as a single row but normally separate into two rows as the thallus widens. The scales are multicellular and hyaline (glassy) in appearance, or violet due to the pigment anthocyanin . Rhizoids are nearly lacking in aquatic forms, but there are usually numerous unicellular rhizoids of two types on
2028-417: The main site of lipids in liverwort cells, and have long been associated with liverwort's often prominent essential oils . A visually striking example of this association can be seen in the distinctly blue oil bodies of Calypogeia azurea , found to be due to the localized accumulation of Azulene derivatives. Another early empirical argument for the association of essential oils and complex oil bodies
2080-419: The mechanism was attributed to carbohydrates and other molecules whose osmoticum resists water loss, inferred to be contained in the oil bodies and noted due to the oil body collapse upon rehydration. A hypothesized ancestral function has been that of UV tolerance. It has been noted that liverworts produce a high amount of constitutive and inducible UV-absorbing compounds, much greater than mosses , however
2132-465: The middle rank is often conspicuously different from the outer ranks; these are called leafy liverworts or scale liverworts . ( See the gallery below for examples. ) Liverworts 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 lack of clearly differentiated stem and leaves in thallose species, or in leafy species
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2184-570: The oil body has since been confirmed in Marchantia polymorpha based upon the micromanipulation of oil cell contents using glass capillaries and piston syringes. Chemical analyses on hundreds of liverwort species have revealed highly diverse mixtures of aromatic and terpenoid compounds, likely associated with oil bodies. The essential oils of liverworts are largely composed of sesquiterpenes as well as diterpenes , and more than 3000 terpenoid and aromatic compounds have been reported from
2236-441: The older parts of the forked thalli die, the younger tips become separate individuals. Some thallose liverworts such as Marchantia polymorpha and Lunularia cruciata produce small disc-shaped gemmae in shallow cups. Marchantia gemmae can be dispersed up to 120 cm by rain splashing into the cups. In Metzgeria , gemmae grow at thallus margins. Marchantia polymorpha is a common weed in greenhouses, often covering
2288-476: The plant Mylia taylorii . They were noted as transparent drops, with a shining, membranous texture. They are secretory organelles bound by a single membrane, containing lipophilic globules in a proteinaceous matrix of high refractive index. They are quite variable in size, number, shape, colour, and content between liverwort species. They may appear rounded, globular, homogenous, segmented, clear or tinted. The lipophilic globules within have been identified as
2340-549: The plants. In vitro studies on the effects of various liverwort extracts have further demonstrated broad feeding-deterrence as well as insecticidal and nematicidal properties. Although noted that liverwort colonies are seldom damaged by fungal or bacterial pathogens, empirical evidence of oil-bodies protecting against invasion is lacking. Extracts from a range of liverwort taxa demonstrate pronounced and diverse antifungal and antibacterial properties. Fungal endophytes however are not uncommon among liverwort taxa, and
2392-491: The presence of deeply lobed or segmented leaves and the presence of leaves arranged in three ranks, as well as frequent dichotomous branching, all point to the plant being a liverwort. With a few exceptions, all liverworts undergo polyplastidic meiosis, in contrast to mosses and hornworts which have monoplastidic meiosis. Unlike any other embryophytes, most liverworts contain unique membrane-bound oil bodies containing isoprenoids in at least some of their cells, lipid droplets in
2444-413: The splashing of raindrops. In 2008, Japanese researchers discovered that some liverworts are able to fire sperm-containing water up to 15 cm in the air, enabling them to fertilize female plants growing more than a metre from the nearest male. When sperm reach the archegonia, fertilisation occurs, leading to the production of a diploid sporophyte. After fertilisation, the immature sporophyte within
2496-435: The two kinds of reproductive structures are borne on different branches of the same plant. In either case, the sperm must move 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 enable them to swim short distances, provided that at least a thin film of water is present. Their journey may be assisted by
2548-441: The ventral surface. One type is called smooth and the other type is the pegged or tuberculated rhizoids; these help in anchorage and absorption. The inner surface of the smooth rhizoids is smooth while that of the tuberculate rhizoid will have internal cell wall projections. One of the more than 100 species in this genus is the "slender riccia" ( Riccia fluitans ), which grows on damp soil or, less commonly, floating in ponds, and
2600-471: 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. Some liverworts are capable of asexual reproduction ; in bryophytes in general "it would almost be true to say that vegetative reproduction is the rule and not the exception." For example, in Riccia , when
2652-481: Was based upon the dark indophenol blue staining of Radula complanata oil bodies; Indophenol blue dissolves in essential oils and appears dark blue, but appear light pink in unsaturated lipids like those found in the cytoplasmic oil droplets of R. complanata . This was later corroborated by chemical analyses which found the primary constituent of R. complanata oil bodies to be the aromatic 3-methoxy-biphenyl. The association between oil bodies and essential oils
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#17327809864892704-406: Was derived from the genus name Marchantia , named by French botanist Jean Marchant after his father. It is estimated that there are about 9000 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 be distinguished from the apparently similar mosses on the basis of
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