| Riccia | |
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| Riccia huebeneriana | |
Scientific classification  | |
| Kingdom: | Plantae |
| Division: | Marchantiophyta |
| Class: | Marchantiopsida |
| Order: | Marchantiales |
| Family: | Ricciaceae |
| Genus: | Riccia L., 1753 |
| Synonyms | |
List
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Riccia is a genus of liverworts in the order Marchantiales. [1]
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. [1] [2]
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 [3] [4] of Northern Australia and Riccia sahyadrica [5] of Western Ghats, the photosynthetic region is confined to the lower half of the thallus. [6]
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. [1]
Rhizoids are nearly lacking in aquatic forms, but there are usually numerous unicellular rhizoids of two types on the ventral surface. [1] 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, [6] and 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. [1]
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. [7]
The following species are recognised in the genus Riccia: [8]
Porella is a large, common, and widespread genus of liverworts in order Porellales. It is a member of the family Porellaceae within that order.
Bazzania is a genus of liverwort in the family Lepidoziaceae.
Calypogeia is a genus of liverworts in the family Calypogeiaceae.
Leptoscyphus is a genus of liverwort in the family Lophocoleaceae.
Schistochila is a genus of liverworts in the order Jungermanniales. It is the only genus in the family Schistochilaceae.
Acrobolbus, synonyms including Marsupidium, is a liverwort genus in the family Acrobolbaceae.
Marsupella is a liverwort genus in the family Gymnomitriaceae.
Riccardia is a plant genus in the liverwort family Aneuraceae.
The Botany of Lord Auckland's Group and Campbell's Island is a description of the plants discovered in those islands during the Ross expedition written by Joseph Dalton Hooker and published by Reeve Brothers in London between 1844 and 1845. Hooker sailed on HMS Erebus as assistant surgeon. It was the first in a series of four Floras in the Flora Antarctica, the others being the Botany of Fuegia, the Falklands, Kerguelen's Land, Etc. (1845–1847), the Flora Novae-Zelandiae (1851–1853), and the Flora Tasmaniae (1853–1859). They were "splendidly" illustrated by Walter Hood Fitch.
Cephalozia is a genus of liverworts belonging to the family Cephaloziaceae.
Lophozia is a genus of liverworts belonging to the family Lophoziaceae. The genus was first described by Barthélemy Charles Joseph Dumortier.
Jungermannia is a genus of leafy liverworts belonging to the family Jungermanniaceae. They have a worldwide distribution.
Anastrophyllum is a genus of liverworts belonging to the family Anastrophyllaceae.
Lophocolea is a genus of liverworts belonging to the family Lophocoleaceae. The genus has a cosmopolitan distribution.
Chiloscyphus is a genus of liverworts belonging to the family Lophocoleaceae.
Drepanolejeunea is a genus of liverworts belonging to the family Lejeuneaceae.
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