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 cells of the amphithecium by further anticline! In this article we will discuss about the g ametophytic phase, reproduction and sporophytic phase in the life cycle of riccia. Many rhizoiu develop later on from the multicellular thallus and fix it on the soil Fig. Along with these divisions the first rhizoid develops at the base of the germ Lube. If you wish to download it, please recommend it to your friends in any social system.
The terminal cells of photosynthetic filaments are large, hyaline and form loose, ill-defined and discontinuous one celled thick epidermis. Each androcyte has a prominent nucleus and a small extra-nuclear granule called blepharopiast.
Life Cycle of Riccia (With Diagram) | Hepaticopsida
Each androcyte thus metamorphosis into an antherozoid Fig. These cells are devoid of chlorophyll and contain starch as reserve food material. The neck canal initials produce a row of four neck canal cells. The canal of the neck contains a row of four neck canal cells dycle is closed at the tip by four lid cells. It consists of compactly arranged parenchymatous cells. Scales contain anthocyanin pigment and when in water absorbs chlorophyll making it liff green.
The archegonia, like the antheridia, are also embedded in the mid-dorsal furrow of the thallus and are arranged in acropetalous order i. Sex organs lie embedded in the mid dorsal section of the thallus between air spaces and filaments.
Thallus is mm long and 1. You can help Wikipedia by expanding it. These antherozoids come up to dorsal surface of the thallus from the antheridial chamber where they swim in the thin film of ricciz and reach the mouth of the neck of the archegonium. The germ tube elongates rapidly to form a club-shaped structure because the content of the cytoplasm move to the distal end.
The lower ventral surface has a mid-ventral ridge bearing multicellular scales that originate as a single ricciw but normally separate into two rows as the thallus widens. Nucleus of each spore mother cell lie by two successive divisions to form 4 haploid nuclei. Some of the cells of the xycle epidermis grow out and elongate forming the rhizoids, while certain cells divide and produce the single layered scales.
One flagellum serves for propulsion and the other for llfe and for changes in direction Fig. The mature sporogonium in Riccia is of very simple structure. 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.
Riccia Structure, Life Cycle, Sexual and Asexual Reproduction
Reproduction in Riccia With Diagram. We think you have liked this presentation. The male and female nuclei fuse together producing a single diploid nucleus.
A bilayered calyptra forms a protective covering around the capsule. Light, low temperature and water is essential for spore germination. Each archegonium develops from a superficial cell situated on the dorsal side about three or four cells away from the growing ,ife.
Life Cycle of Riccia (With Diagram) | Hepaticopsida
Rhizoids and scales serve as anchors for the plant. This mucilaginous mass consists of chemical substances such as soluble proteins and certain inorganic salts of potassium. This represents octant stage Fig. Repeated dichotomy results into a typically rosette like appearance Figs.
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A vertical cross section of the thallus shows two distinct zones, viz. The last division in each androgonial cell is diagonal thus producing two androcytes antherozoid mother cells. The lower group of Peripheral cells by further anticlinal divisions produces a single layered wall of the venter.
The spores are tetrahedrally arranged Fig. This species can also grow on soil. Water helps in the dehiscence of the anheridium. Sexual reproduction in Riccia is oogamous. Periclinal divisions then take place in these octants producing outer jacket initials and inner androgonial initials.
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In Riccia cruciata only two dichotomy result in a cruciate form Fig. Tubers are common in Riccia discolor, R. In aquatic form of Riccia fluitans epidermis is continuous and air chambers are almost completely closed. Scales are arranged in a transverse row and may be membranous, multicellular, single celled, and with colours ranging from pink, red, violet and black. Antheridial chamber, in which an antheridium lies, communicates with the clorsal surface of the thallus by terminal opening.
The cells of inner layer of the venter wall the sporogonial wall along with some spore mother cells disorganize producing a viscous liquid. The fusion of the nuclei of male and female gamete results in the formation of diploid zygote or oospore. Scales are arranged all riccja the margin in a single row.