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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Rhizoids are nearly lacking in aquatic forms, but there are usually numerous unicellular rhizoids of two types on the ventral surface.
Riccia Structure, Life Cycle, Sexual and Asexual Reproduction
Simultaneously the primary axial small cell divides transversely and unequally to form small upper primary cover cell and large lower central cell Fig. The venter contains a lower larger llife, the egg or oosphere, and a smaller upper lofe known as the ventral canal cell. Several antherozoids may enter a single archegonium but only one of them fuses with the egg for fertilization.
Sex organs develop in acropetal succession i. 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.
Botany Department”— Presentation transcript: The germ tube elongates rapidly to form a club-shaped structure because the content of the cytoplasm move to the distal end. This mucilaginous mass consists of chemical substances such as soluble proteins and certain inorganic salts of potassium. In certain species R.
These ceils resulting in the production of an outer layer of jacket initials or amphithecium and an inner mass of archesporial initials or endothecium. My presentations Profile Feedback Log out. The basal swollen portion of the archegonium is known as the rriccia and the upper elongated portion as the neck.
They are haploid uninucleate and pyramidal in shape Fig. Primary antheridial kife divide by two successive vertical divisions at right angle to each ricfia to form two tiers of cycke cells each Fig.
Then the periclinal divisions take place in. The lower group of Peripheral cells by further anticlinal divisions produces a single layered wall of the venter. Depending on species, the thallus may be strap-shaped and about 0. In India a in polyploid species gaugetica Udar and Chopra reported 24 n and 48 In chromosomes number.
Ricciaceae Marchantiales genera Bryophyte stubs. Outer cell divides by transverse divisions to form a filament of 4 cells.
This initial enlarges, becomes papillate and first divides transversely into a basal cell and an outer cell Fig. After fertilization the cyxle zygote or oospore enlarges until it completely fills the cavity of the venter of the archegonium. Tubers are common in Riccia discolor, R. The vegetative plant or thallus in Riccia, is a gametophyte, whose cells are haploid.
In Riccia crustissi two spores of a tetrad develop into male thalli and two spores develop into female thalli. Sexual reproduction in Riccia is oogamous. This page was last edited on 16 Octoberat Retrieved from ” https: The ventral side also bears scales which are formed of a single layer of cells and are arranged in two rows in the older parts of the thallus while lif the younger parts these scales are in one row and in the apical region are crowded below the notch for the protection of the growing point.
This represents octant stage Fig. The cells of inner layer of the venter wall the sporogonial wall along with some spore mother cells disorganize producing a viscous liquid.
Riccia Ms. Inderveena Sharma H.O.D. Botany Department – ppt video online download
Each androcyte thus metamorphosis into an antherozoid Fig. The thallus of Riccia has a simple structure and is formed lifr parenchymatous rjccia which are bounded on both sides by the upper and lower epidermis. Neck initials tier divides by repeated transverse divisions to form a tube-like neck.
They develop as prolongations of the lower epidermal cells. Each archegonium is a flask-shaped structure having a multi-cellular stalk. It is made of somewhat vertical rows of un-branched photosynthetic filaments.
There are no elaters. For the completion of the whole life cycle the gametophyte produces the sporophyte, this sporophyte produces the gametophyte again, and these two generation regularly alternate with each other. Rhizoids and scales are absent Fig.
There is no particular time for the development of sex organs, and therefore one can see all the developmental irccia in the different sections of the same thallus. The wall of the antheridium consists of a single layer of cells and encloses a mass of androcytes or antherozoid mother cells.
Life Cycle of Riccia (With Diagram) | Hepaticopsida
The of the mature capsule consists of a single layer of cells surrounding a mass of spore mother cells. Articles with ‘species’ microformats All stub articles.
This gamete producesmale antherozoids and female oosphere gamete surrounding vegetative tissue.