''Riccia'' is a genus of

liverwort Liverworts are a group of non-vascular land plants forming the division Marchantiophyta (). They may also be referred to as hepatics. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry ...

s in the order Marchantiales.

Description

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 is dorsiventrally differentiated. Its upper (dorsal) surface is green and

chlorophyll Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words (, "pale green") and (, "leaf"). Chlorophyll allows plants to absorb energy ...

-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 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 A hyaline substance is one with a glassy appearance. The word is derived from , and . Histopathology Hyaline cartilage is named after its glassy appearance on fresh gross pathology. On light microscopy of H&E stained slides, the extracellula ...

(glassy) in appearance, or violet due to the pigment

anthocyanin Anthocyanins (), also called anthocyans, are solubility, water-soluble vacuole, vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart named a chemical compou ...

Rhizoid Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be un ...

s are nearly lacking in aquatic forms, but there are usually numerous unicellular rhizoids of two types on 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 A cell wall is a structural layer that surrounds some Cell type, cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid. Primarily, it provides the cell with structural support, shape, protection, ...

projections.

Distribution and habitat

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,MacVicar, Symers M. 1971. The student's handbook of British hepatics, p. 12-13. Hitchen Whelden & Wesley, Ltd.; Authorized reprint of the 1926 edition published by Sumfield & Day, Ltd. and is sometimes used in

aquarium An aquarium (: aquariums or aquaria) is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. fishkeeping, Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aquati ...

Reproduction

Plants are usually

monoicous Monoicy () is a sexual system in haploid plants (mainly bryophytes) where both sperm and eggs are produced on the same gametophyte, in contrast with dioicy, where each gametophyte produces only sperm or eggs but never both.Crandall-Stotler, B.J ...

, and sexual reproduction is by antheridia and archegonia. Asexual reproduction occurs by

spores In biology, a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plant ...

, by fragmentation of the rosettes, and by formation of apical

tubers Tubers are a type of enlarged structure that plants use as storage organs for nutrients, derived from stems or roots. Tubers help plants perennate (survive winter or dry months), provide energy and nutrients, and are a means of asexual reprod ...

. Spores are large (45 to 200 μ) and formed in tetrads. The

sporophyte A sporophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the biological life cycle, life cycles of plants and algae. It is a diploid multicellular organism which produces asexual Spo ...

of Riccia is the simplest amongst

bryophyte Bryophytes () are a group of embryophyte, land plants (embryophytes), sometimes treated as a taxonomic Division (taxonomy), division referred to as Bryophyta ''Sensu#Common qualifiers, sensu lato'', that contains three groups of non-vascular pla ...

s. It consist of only a capsule, missing both foot and seta, and does not perform photosynthesis.

Species

The following species are recognised in the genus ''Riccia'': *'' Riccia abdita'' Cargill *'' Riccia abuensis'' Bapna *'' Riccia acutisulca'' Steph. *'' Riccia alatospora'' O.H. Volk & Perold *'' Riccia albida'' Sull. ex Austin *'' Riccia albolimbata'' S.W. Arnell *'' Riccia albomarginata'' Bisch. ex C. Krauss *'' Riccia alboporosa'' Perold *'' Riccia albopunctata'' Jovet-Ast *'' Riccia albornata'' O.H. Volk & Perold *'' Riccia albovestita'' O.H. Volk *'' Riccia amboinensis'' Schiffn. *'' Riccia ampullacea'' Perold *'' Riccia anatolica'' Özenoğlu & Kırmacı *'' Riccia angolensis'' Steph. *'' Riccia arachnoidea'' O.F. Müll. *'' Riccia aravalliensis'' Pandé & Udar *'' Riccia argenteolimbata'' O.H. Volk & Perold *'' Riccia arnellii'' Sultan Khan *'' Riccia asprella'' Carrington & Pearson *'' Riccia asservanda'' De Not. *'' Riccia atlantica'' Sérgio & Perold *'' Riccia atromarginata'' Levier *'' Riccia atropurpurea'' Sim *'' Riccia attenuata'' Pandé *'' Riccia auriformis'' With. *'' Riccia australis'' Steph. *'' Riccia bahiensis'' Steph. *'' Riccia balansae'' Steph. *'' Riccia beyrichiana'' Hampe ex Lehm. *'' Riccia bialbistrata'' Hässel *'' Riccia bicarinata'' Lindb. *'' Riccia bicolorata'' Perold *'' Riccia bifurca'' Hoffm. *'' Riccia billardieri'' Mont. & Nees *'' Riccia biokoensis'' Perold *'' Riccia blackii'' Na-Thalang *'' Riccia boliviensis'' Jovet-Ast *'' Riccia boumanii'' Dirkse, Losada-Lima & M. Stech *'' Riccia brasiliensis'' Schiffn. *'' Riccia breidleri'' Jur. *'' Riccia breutelii'' Hampe ex Steph. *'' Riccia brittonii'' M. Howe *'' Riccia bullosa'' Link *'' Riccia californica'' Austin *'' Riccia campbelliana'' M. Howe *'' Riccia canaliculata'' Hoffm. *'' Riccia cancellata'' Taylor *'' Riccia caroliniana'' Na-Thalang *'' Riccia cartilaginosa'' Steph. *'' Riccia cavernosa'' Hoffm. *'' Riccia chartacea'' K.I. Goebel *'' Riccia chiapasensis'' Jovet-Ast *'' Riccia chinensis'' Herzog *'' Riccia chrysocrinita'' Cargill *'' Riccia chudoana'' Steph. *'' Riccia ciliata'' Hoffm. *'' Riccia ciliifera'' Link ex Lindenb. *'' Riccia cincta'' Jovet-Ast *'' Riccia collata'' Na-Thalang *'' Riccia compacta'' Garside *'' Riccia concava'' Bisch. ex Gottsche *'' Riccia congoana'' Steph. *'' Riccia convexa'' Steph. *'' Riccia coracina'' Jovet-Ast *'' Riccia coronata'' Sim *'' Riccia corrugata'' Jovet-Ast *'' Riccia crassa'' Steph. *'' Riccia crassifrons'' Spruce *'' Riccia crassivenia'' Jovet-Ast *'' Riccia crenatodentata'' O.H. Volk *'' Riccia crinita'' Taylor *'' Riccia crozalsii'' Levier *'' Riccia cruciata'' Kashyap *'' Riccia crustata'' Trab. *'' Riccia crystallina'' L. *'' Riccia cubensis'' S.W. Arnell *'' Riccia cupulifera'' A.V. Duthie & Garside *'' Riccia curtisii'' (Austin) Austin *'' Riccia delavayi'' Steph. *'' Riccia deserticola'' Steph. *'' Riccia dictyospora'' M. Howe *'' Riccia discolor'' Lehm. & Lindenb. *'' Riccia duplex'' Lorb. & Müll. Frib. *'' Riccia dussiana'' Steph. *'' Riccia eburnea'' Jovet-Ast *'' Riccia ekmanii'' S.W. Arnell *'' Riccia elliottii'' Steph. *'' Riccia elongata'' Perold *'' Riccia enyae'' Jovet-Ast *'' Riccia epecenia'' Cargill *'' Riccia erubescens'' Perold *'' Riccia erythrocarpa'' Jovet-Ast *'' Riccia esulcata'' Steph. *'' Riccia fertilissima'' Steph. *'' Riccia fluitans'' L. *'' Riccia frostii'' Austin *'' Riccia fruchartii'' Steph. *'' Riccia furfuracea'' Perold *'' Riccia gangetica'' Ahmad ex L. Söderstr., A. Hagborg & von Konrat *'' Riccia garsidei'' Sim *'' Riccia geissleriana'' Jovet-Ast *'' Riccia gemmifera'' O.H. Volk *'' Riccia glauca'' L. *'' Riccia gothica'' Damsh. & Hallingb. *'' Riccia gougetiana'' Durieu & Mont. *'' Riccia grandis'' Nees *'' Riccia grollei'' Udar *'' Riccia handelii'' Schiffn. *'' Riccia hantamensis'' Perold *'' Riccia hasskarliana'' Steph. *'' Riccia hawaiiensis'' Hürl. *'' Riccia hegewaldiana'' Jovet-Ast *'' Riccia helenae'' Jovet-Ast *'' Riccia hirsuta'' O.H. Volk & Perold *'' Riccia hirta'' (Austin) Underw. *'' Riccia horrida'' Jovet-Ast *'' Riccia hortorum'' Bory ex Lindenb. *'' Riccia howellii'' M. Howe *'' Riccia huebeneriana'' Lindenb. *'' Riccia ianthina'' Jovet-Ast *'' Riccia indica'' Udar & A. Gupta *'' Riccia indira-gandhiensis'' Dabhade & A. Hasan *'' Riccia inflexa'' Taylor *'' Riccia intermedia'' Roum. *'' Riccia iodocheila'' M. Howe *'' Riccia jodhpurensis'' Bapna *'' Riccia jovet-astiae'' E. Vianna *'' Riccia junghuhniana'' Nees & Lindenb. *'' Riccia keralensis'' Manju, Chandini, Sushil K. Singh & K.P. Rajesh *'' Riccia kirinensis'' C. Gao & K.C. Chang *'' Riccia lamellosa'' Raddi *'' Riccia lanceolata'' Steph. *'' Riccia laxisquamata'' (Steph.) Steph. *'' Riccia leptothallus'' R.M. Schust. *'' Riccia liaoningensis'' C. Gao & K.C. Chang *'' Riccia ligula'' Steph. *'' Riccia limbata'' Bisch. *'' Riccia limicola'' Jovet-Ast *'' Riccia lindmanii'' Steph. *'' Riccia linearis'' (Schiffn.) Steph. *'' Riccia luticola'' Na-Thalang *'' Riccia macallisteri'' M. Howe *'' Riccia macrocarpa'' Levier *'' Riccia macrospora'' Steph. *'' Riccia mamillata'' Trab. ex Steph. *'' Riccia mammifera'' O.H. Volk & Perold *'' Riccia mamrensis'' Perold *'' Riccia mangalorica'' Ahmad ex Jovet-Ast *'' Riccia mauryana'' Steph. *'' Riccia melanospora'' Kashyap *'' Riccia membranacea'' Gottsche & Lindenb. *'' Riccia michelii'' Raddi *'' Riccia microciliata'' O.H. Volk & Perold *'' Riccia miyakeana'' Schiffn. *'' Riccia moenkemeyeri'' Steph. *'' Riccia montana'' Perold *'' Riccia multifida'' (Steph.) F.M. Bailey *'' Riccia muscicola'' Steph. *'' Riccia namaquensis'' Perold *'' Riccia natalensis'' Sim *'' Riccia nigerica'' E.W. Jones *'' Riccia nigrella'' DC. *'' Riccia nigrescens'' Mont. *'' Riccia nipponica'' S. Hatt. *'' Riccia novohannoverana'' Schiffn. *'' Riccia numeensis'' Steph. *'' Riccia obchantiana'' Cargill *'' Riccia obtusa'' Meijer *'' Riccia oerstediana'' Lindenb. & Hampe *'' Riccia okahandjana'' S.W. Arnell *'' Riccia olgensis'' Na-Thalang *'' Riccia oryzicola'' T. Tominaga & Furuki *'' Riccia ozarkiana'' McGregor *'' Riccia pandei'' Udar *'' Riccia papillispora'' Steph. *'' Riccia papillosa'' Moris *'' Riccia papulosa'' (Steph.) Steph. *'' Riccia paraguayensis'' Spruce *'' Riccia paranaensis'' Hässel *'' Riccia parvoareolata'' O.H. Volk & Perold *'' Riccia pathankotensis'' Kashyap *'' Riccia perennis'' Steph. *'' Riccia perssonii'' Sultan Khan *'' Riccia perthiana'' Steph. ex K.I. Goebel *'' Riccia planobiconvexa'' Steph. *'' Riccia polycarpa'' (Trab.) Jelenc *'' Riccia porosa'' Taylor *'' Riccia pottsiana'' Sim *'' Riccia prominens'' Meijer *'' Riccia pseudofluitans'' C. Gao & K.C. Chang *'' Riccia pubescens'' S. Hatt. *'' Riccia pullulans'' Jovet-Ast *'' Riccia pulveracea'' Perold *'' Riccia purpurascens'' Lehm. *'' Riccia pyramidata'' Willd. *'' Riccia radiata'' Perold *'' Riccia radicosa'' Pearson *'' Riccia rechingeri'' Steph. *'' Riccia reticulata'' Sw. *'' Riccia reticulatula'' Udar *'' Riccia rhenana'' Lorb. ex Müll. Frib. *'' Riccia ridleyi'' A. Gepp *'' Riccia rorida'' Na-Thalang *'' Riccia rosea'' O.H. Volk & Perold *'' Riccia rubricollis'' Garside & A.V. Duthie ex S.W. Arnell *'' Riccia runssorensis'' Steph. *'' Riccia saharensis'' Steph. ex Jovet-Ast *'' Riccia sahyadrica'' Manju & Cargill *'' Riccia sanguineisporis'' Jovet-Ast *'' Riccia sarieae'' A.E.D. Daniels & D.T.T. Daniels *'' Riccia satoi'' S. Hatt. *'' Riccia schelpei'' O.H. Volk & Perold *'' Riccia schroederi'' Steph. *'' Riccia schweinfurthii'' Steph. *'' Riccia sibayenii'' Perold *'' Riccia simii'' Perold *'' Riccia singularis'' Jovet-Ast *'' Riccia sinuata'' Huds. *'' Riccia somaliensis'' Perold *'' Riccia sommieri'' Levier *'' Riccia sorocarpa'' Bisch. *'' Riccia spongiosula'' Na-Thalang *'' Riccia squamata'' Nees *'' Riccia stricta'' (Lindenb.) Perold *'' Riccia subbifurca'' Warnst. ex Croz. *'' Riccia subcrinita'' You L. Xiang & R.L. Zhu *'' Riccia subdepilata'' Jovet-Ast *'' Riccia subplana'' Steph. *'' Riccia subtilis'' (Steph.) Steph. *'' Riccia sumatrana'' Meijer *'' Riccia symoensii'' Vanden Berghen *'' Riccia taeniaeformis'' Jovet-Ast *'' Riccia tasmanica'' Steph. ex Rodway *'' Riccia tenella'' D.L. Jacobs *'' Riccia tomentosa'' O.H. Volk & Perold *'' Riccia trabutiana'' Steph. *'' Riccia trachyglossum'' Perold *'' Riccia treubiana'' Steph. *'' Riccia triangularis'' Steph. *'' Riccia tuberculata'' Lam. & Poir. *'' Riccia tuberosa'' Taylor *'' Riccia udarii'' Kanwal *'' Riccia velenovskyi'' Kavina *'' Riccia velimalaiana'' A.E.D. Daniels & P. Daniel *'' Riccia verrucosa'' Cargill *'' Riccia viannae'' Jovet-Ast *'' Riccia victoriensis'' Steph. *'' Riccia villosa'' Steph. *'' Riccia violacea'' M. Howe *'' Riccia vitalii'' Jovet-Ast *'' Riccia vitrea'' Perold *'' Riccia volkii'' S.W. Arnell *'' Riccia vulcanicola'' Eb. Fisch. *'' Riccia wainionis'' Steph. *'' Riccia warnstorfii'' Limpr. ex Warnst. *'' Riccia weymouthiana'' Steph. ex Rodway

References

{{Authority control Ricciaceae Marchantiales genera