Riccia is a genus of liverworts 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-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 Na-Thalang, O., 1980. A revision of the genus Riccia (Hepaticae) in Australia. Brunonia, 3(1), pp. 61–140.Cargill, D.C., Neal, W.C., Sharma, I. and Gueidan, C., 2016. A preliminary molecular phylogeny of the genus Riccia L.(Ricciaceae) in Australia. Australian Systematic Botany, 29(3), pp. 197–217. of Northern Australia and Riccia sahyadrica Cargill, D.C., Manju, C.N., Deepa, K.M., Chandini, V.K. and Rajesh, K.P. 2019. A New Indian Species of Riccia with connections to Northern Australia. Journal of Bryology 42, DOI. https://doi.org/10.1080/03736687.2019.1611249 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 (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 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.
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 aquariums.
Reproduction 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 consists of only a capsule, missing both foot and seta, and does not perform photosynthesis.Text Book Of Botany Diversity Of Microbes And Cryptogams
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
External links A liverwort, Riccia sp L. by Isidro A. T. Savillo