liverwort


liverwort
/liv"euhr werrt', -wawrt'/, n.
any mosslike plant of the class Hepaticae, growing chiefly on damp ground, rocks, or on tree trunks and helping the decay of logs and the disintegration of rocks.
[bef. 1100; ME; late OE liferwyrt. See LIVER1, WORT2]

* * *

Any of more than 8,000 species of small, nonvascular, spore-producing land plants that make up the class Hepatopsida (or Hepaticae) of bryophytes, found worldwide but mostly in the tropics.

Thallose liverworts commonly grow on moist soil or damp rocks; leafy liverworts are found in similar habitats and on tree trunks in damp woods. Sexual (gametophyte) and asexual (sporophyte) generations alternate in the life cycle (see alternation of generations). The thallus of thallose liverworts, resembling a lobed liver, gives liverworts their name. Though not economically important to humans, liverworts provide food for animals, facilitate the decay of logs, and aid in the disintegration of rocks by their ability to retain moisture.

* * *

plant
      (class Hepatopsidae), any of more than 8,000 species of small, nonvascular, spore-producing land plants constituting part of the division Bryophyta. They include the thallose liverworts that show branching, ribbonlike gametophytes and the leafy liverworts (leafy liverwort) (mainly in the order Jungermanniales). The six orders of liverworts are segregated primarily on gametophyte structures, with sporophyte features also supporting the classification. One additional order formerly classified as liverworts (Takakiales) is now placed among the mosses.

 Liverworts are distributed worldwide, though most commonly in the tropics. Thallose liverworts grow commonly on moist soil or damp rocks, while leafy liverworts are found in similar habitats as well as on tree trunks in damp woods. The thallus of thallose liverworts resembles a lobed liver—hence the common name liverwort (“liver plant”). Filamentous structures called rhizoids anchor most liverworts to their substrata, except for the few genera that are aquatic.

      Sexual ( gametophyte) and asexual ( sporophyte) generations characterize a liverwort life cycle. The gametophyte generation develops from a germinating spore. Sperm from the male reproductive organ (antheridium) travel through an aqueous environment, and one sperm fertilizes an egg that is still retained in the female reproductive organ (archegonium). The sporophyte develops from this embryo and forms a sporangium at its apex. Spores are released when the sporangium ruptures, marking the start of a new gametophytic generation. Asexual reproduction occurs by means of gemmae, which are produced by the gametophytic generation or by separation of branches of that plant body, resulting in new plants.

      Liverworts are not economically important to humans but do provide food for animals, facilitate the decay of logs, and aid in the disintegration of rocks by their ability to retain moisture.

      The most ancient liverwort fossil—Pallaviciniites devonicus, thought to be a member of the order Metzgeriales—dates to the Upper Devonian Period (about 385 to 359 million years ago). It resembles a thallose liverwort.

* * *


Universalium. 2010.

Synonyms:

Look at other dictionaries:

  • Liverwort — may refer to either * Marchantiophyta, a division of non vascular plants. * Hepatica , a genus of spring flowers.Liverwort is the common name for Phlym Hepatophyta which belongs to Kingdom Plantae. Hepatophytes are the nonvascular plants …   Wikipedia

  • Liverwort — Liv er*wort , n. (Bot.) 1. A ranunculaceous plant ({Anemone Hepatica}) with pretty white or bluish flowers and a three lobed leaf; called also {squirrel cups}. [1913 Webster] 2. A flowerless plant ({Marchantia polymorpha}), having an irregularly… …   The Collaborative International Dictionary of English

  • liverwort — late O.E. lifenwyrt, from lifer (see LIVER (Cf. liver) (n.1)) + wyrt (see WORT (Cf. wort)). A loan translation of M.L. hepatica. Applied to various plants with liver shaped leaves or that were used to treat liver disorders. Cf. Ger. leberkraut …   Etymology dictionary

  • liverwort — ► NOUN ▪ a small flowerless green plant with leaf like stems or lobed leaves, lacking true roots and reproducing by spores …   English terms dictionary

  • liverwort — [liv′ər wʉrt΄] n. [ME: see LIVER1 & WORT2: so called from having liver shaped parts] any of two classes (Hepaticopsida and Anthocerotopsida) of bryophytes, often forming dense, green, mosslike mats on logs, rocks, or soil in moist places …   English World dictionary

  • liverwort — Hepatica He*pat i*ca, n.; pl. {Hepatic[ae]}. [NL. See {Hepatic}. So called in allusion to the shape of the lobed leaves or fronds.] [1913 Webster] 1. (Bot.) A genus of pretty spring flowers closely related to Anemone; squirrel cup. [1913 Webster] …   The Collaborative International Dictionary of English

  • Liverwort — Hepaticophyta Hépatiques …   Wikipédia en Français

  • liverwort — žibuoklė statusas T sritis vardynas apibrėžtis Šeima. Vėdryniniai – Ranunculaceae Juss. atitikmenys: lot. Hepatica angl. hepatica; liverwort vok. Leberblümchen rus. перелеска; печeночница lenk. przylaszczka …   Dekoratyvinių augalų vardynas

  • liverwort — noun Date: before 12th century 1. any of a class (Hepaticae) of bryophytic plants characterized by a thalloid gametophyte or sometimes an upright leafy gametophyte that resembles a moss 2. hepatica …   New Collegiate Dictionary

  • liverwort — noun /ˈlɪv.ə.wɜːt,ˈlɪv.ɚ.wɝːt,ˈlɪv.ɚ.wɔːrt/ A bryophyte (includes mosses, liverworts, and hornworts) with a leafy stem or leafless thallus characterized by a dominant gametophyte stage and a lack of stomata on the sporophyte stage of the life… …   Wiktionary


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.