• 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.

  • Leafy species can be distinguished from the apparently similar mosses on the basis of a number of features, including their single-celled rhizoids.

  • [50][54] It also includes the problematic genus Monoclea, which is sometimes placed in its own order Monocleales.

  • [9] Other differences are not universal for all mosses and all liverworts;[8] 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,[10][11] as well as frequent dichotomous branching, all point to the plant being a liverwort.

  • However, certain species may cover large patches of ground, rocks, trees or any other reasonably firm substrate on which they occur.

  • [13] Cells in 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.

  • 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
    a lack of clearly differentiated stem and leaves all point to the plant being a liverwort.

  • [45] 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.

  • Liverworts are typically small, usually from 2–20 mm wide with individual plants less than 10 cm long, and are therefore often overlooked.

  • [30] Liverworts are more commonly found in moderate to deep shade, though desert species may tolerate direct sunlight and periods of total desiccation.

  • [61] 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”.

  • However, most liverworts produce flattened stems with overlapping scales or leaves in two or more ranks, the middle rank is often conspicuously different from the outer ranks;
    these are called leafy liverworts or scale liverworts.

  • 2000[3]; Classes and orders: Haplomitriopsida, Calobryales, Treubiales, Marchantiopsida, Blasiales, Lunulariales, Marchantiales, Neohodgsoniales, Sphaerocarpales, Jungermanniopsida,
    Fossombroniales, Jungermanniales, Metzgeriales, Pallaviciniales, Pelliales, Pleuroziales, Porellales, Ptilidiales Physical characteristics Description[edit] 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,[6] so they are often overlooked.

  • In monoicous liverworts, the two kinds of reproductive structures are borne on different branches of the same plant.

  • • The Marchantiopsida includes the three orders Marchantiales (complex-thallus liverworts), and Sphaerocarpales (bottle hepatics), as well as the Blasiales (previously placed
    among the Metzgeriales).

  • 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.

  • Although there is no consensus among bryologists as to the classification of liverworts above family rank,[49] the Marchantiophyta may be subdivided into three classes:[50][51][52][53]
    • The Jungermanniopsida includes the two orders Metzgeriales (simple thalloids) and Jungermanniales (leafy liverworts).

  • As in other land plants, the female organs are known as archegonia (singular: archegonium) and are protected by the thin surrounding perichaetum (plural: perichaeta).

  • Classification Relationship to other plants[edit] 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).

  • An unrelated flowering plant, Hepatica, is sometimes also referred to as liverwort because it was once also used in treating diseases of the liver.

  • [28] 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.

  • 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.

  • [29] As with most groups of living plants, they are most common (both in numbers and species) in moist tropical areas.

  • [12] The sporophyte of many liverworts are non-photosynthetic, but there are also several that are photosynthetic to various degrees.

  • [46] 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

  • [26] Marchantia polymorpha is a common weed in greenhouses, often covering the entire surface of containers;[27]: 230  gemma dispersal is the “primary mechanism by which liverwort
    spreads throughout a nursery or greenhouse.

  • [48] In addition to this taxon-based name, the liverworts are often called Hepaticophyta.

  • They are distributed globally in almost every available habitat, most often in humid locations although there are desert and Arctic species as well.

  • Liverwort species may be either dioicous or monoicous.

  • “[23] For example, in Riccia, when the older parts of the forked thalli die, the younger tips become separate individuals.


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