Riccia is a genus of liverworts in the order Marchantiales. These plants are small and thallose, that is not differentiated into root, stem and leaf. Depending on. Riccia is a thallose liverwort in which the vegetative plant, which is a gametophyte, generally forms rosettes due to the crowded growth of the thallus lobes this. Riccia description with images for under graduate students. the gametophytic phase of the life cycle ends with the formation of zygote.
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The neck consists of six vertical rows enclosing four neck canal cells. Riccia is a genus of liverworts in the order Marchantiales. Germinal tube is filled with cytoplasm which contains albumin granules, chloroplasts and oil granules.
life cycle of riccia –
The wall of the venter is also formed of a single layer of cells which are arranged in several vertical rows. Vegetative reproduction in Riccia is quite common and takes place by the following methods: The price of the …. The sporophyte of Riccia is the ricvia amongst bryophytes. However, in the terrestrial form of this species each air chamber opens on the upper surface by a small opening Fig.
Riccia Ms. Inderveena Sharma H.O.D. Botany Department – ppt video online download
rixcia The thallus continues its growth at the apex while the development of the antheridia is going on, therefore, the mature antheridia are lying some distance back from the apex. The act of fertilization also stimulates the division of the wall of the venter. Photosynthetic filaments are separated from each other by narrow longitudinal vertical canals called air chambers.
In the upper two cells of the row two vertical divisions take place at right angle to each other producing a group of eight ceils or octants. In the majority of species the assimilatory region is formed of vertical rows of cells which are about six to eight cells in height and are separated by large air spaces, the cells of these filaments are rich in chloroplasts as these form the main photosynthetic tissue. These plants are small and thallosethat is not differentiated into root, stem and leaf.
The basal or the posterior part of the thallus starts rotting or disintegrating due to ageing or drought. The thallus is dorsiventrally differentiated. It has a single-layered capsule wall which encloses spores.
When this process of disintegration or decay reaches up to the place of dichotomy, the lobes of the thallus get separated. Each antheridium develops near the apex from a superficial cell which divides transversely into a lower basal cell and an outer cell.
Ricciaceae Marchantiales genera Bryophyte stubs. The apical part of the young rhizoids divides and re-divides to form a gemma like mass of cells in some species e. At the end it divides by a transverse division to form a small cell Fig. This archegoniai initial divides by a transverse division into an upper primary cell and a lower primary stalk ot. Later, it grows deep into the soil and becomes thick.
Upper epidermis is discontinuous and has non-green cells. Primary venter cell divides only once and forms a small venter canal cell and a large egg Fig. The thallus of Riccia has a simple structure and is formed of parenchymatous cells which are bounded on both riccia by the upper and lower epidermis.
Riccia Ms. Inderveena Sharma H.O.D. Botany Department
The cells of inner layer of the venter wall the sporogonial wall along with some spore mother cells disorganize producing a viscous liquid. The spores are released by the bursting of the wall of the enlarged venter which is comparable to the calyptra of other liverworts The release of spores is delayed for a long time till the decay Of the vegetative cyccle which may take even a year or so after the maturation of spores. The oospore increases very much in size filling the whole cavity of the venter.
Retrieved from ” https: One flagellum serves for propulsion and the other for rotation and for changes in direction Fig.
Some of the cells of the lower epidermis grow out and rivcia forming the rhizoids, while certain cells divide and produce the single layered scales. The Hepaticae and Anthocerotae of North America. It is a few cells away from the apical cell. Lfie represents quadrant stage Fig. Rhizoids are nearly lacking in aquatic forms, but there are usually numerous unicellular rhizoids of two types on the ventral surface.
Along with these divisions the first rhizoid develops at the base of the germ Lube. The last division in each androgonial cell is diagonal thus producing two androcytes antherozoid mother cells. A mature antheridium has a short stalk and oval shaped body with a flat base and conical apex Fig.
Six jacket initials divide transversely into upper neck initials tier and lower venter initial tier Fig.