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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Primary venter cell divides only once and forms a small venter canal cell and a ot egg Fig. Both the androcytes remain enclosed in the wall of the androcyte mother cell with one separate wall Fig. My presentations Profile Feedback Log out.
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Four cover cells are present at the top of the neck Fig. Primary androgonial cells divide be several repeated transverse and vertical divisions resulting in the formation of large number of small cubical androgonial cells Fig. In first division the chromosome number is reduced to half of the somatic number. One flagellum serves for propulsion and the other for rotation and for changes in direction Fig.
The last generation of the androgonial cells is known as androcyte mother cells. An 8-called stage thus results. Neck of the archegonium consists of six vertical rows and each row consists six to nine cells. The androcyte soon looses its triangular shape and becomes somewhat round or oval Fig.
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Internally the thallus is differentiated into two regions, upper assimilatory region and the lower storage region. The act of fertilization also stimulates the division of the wall of the venter.
The dorsal surface is light green or dark green body, each branch having a thick ctcle. Each spore remains ricccia by three layers i. Plants Land plants retain derived features they share with green algae: The archegonia, like the antheridia, are also embedded in the mid-dorsal furrow of the thallus and are arranged in acropetalous order i.
Riccia Ms. Inderveena Sharma H.O.D. Botany Department – ppt video online download
These antherozoids come up to dorsal surface of the thallus from the antheridial chamber where they swim in the thin film of water and reach the mouth of the neck of the archegonium. This archegoniai initial divides by a transverse division into an upper primary cell and a lower primary stalk cell.
This gamete producesmale antherozoids and female oosphere gamete surrounding vegetative tissue. Then the periclinal divisions take place in. In Riccia crystallina the scales are inconspicuous and absent.
One of the antherozoids penetrates the egg and fertilization is effected Fig. Riccia plants, like other liverworts, multiply vegetatively by the decay or death of the Older parts which results in the separation of younger branches, each of which grows into an independent plant.
OK Moss Life Cycle. Each archegonium is a flask-shaped structure having a multi-cellular stalk. The capsule wall and inner layer of calyptra break down before the spore mother cells divide to form the spores.
These cells are called jacket initials. This species can also grow on soil. Lfie cell remains embedded in the tissue of thallus, undergoes only a little further development and forms the embedded portion of the antheridial stalk.
All rixcia spore mother cells in a sporogonium are generally transformed into spores there are no sterile cells or elaters. The cells of inner layer of the venter wall the sporogonial wall along fycle some spore mother cells disorganize producing a viscous liquid.
The newly formed young gametophyte remains enclosed with in the old gametophyte Fig. The cells of the amphithecium divide only by anticlinal division to form a single-layered sterile jacket or capsule wall.
It is more a method of perennation rather than multiplication. It cuts a number of cells on its left and right side to form the multicellular thallus Fig. The scales are multicellular and hyaline glassy in appearance, or violet due to rccia pigment anthocyanin. It is a few cells away from the apical cell. Some of the cells of the lower epidermis grow out and elongate forming ,ife rhizoids, while certain cells divide and produce the single layered scales.