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 antheridial cells divide by two successive vertical divisions at right angle to each other to form two tiers of four cells each Fig.
Auth with social network: In Riccia cruciata only two dichotomy result in a cruciate form Fig. Sexual reproduction in Riccia is oogamous.
Riccia Ms. Inderveena Sharma H.O.D. Botany Department – ppt video online download
Growing point is situated in the apical notch. Along lifr these divisions the first rhizoid develops at the base of the germ Lube. The antherozoids are released in the surrounding water by the bursting of the antheridial wall and then these swim freely in the water. Each androcyte mother cell divides by a diagonal mitotic division to form two triangular cells called androcytes.
Mosses and Their Allies. The act of fertilization also stimulates the division of the wall of the venter. Answer Now and help others. ,ife thallus rriccia branched and has a dorsal median groove and ventral median ridge. Due to prolonged dry summer or towards the end of growing season the whole thallus in some species e.
The cells of the amphithecium divide only by anticlinal division to form a single-layered sterile jacket or capsule wall.
Air chambers spaces help in the gaseous exchange. The capsule wall and inner layer of calyptra break down before the spore mother cells divide to form the spores. These cells become softened and finally breakdown to release mass of antherozoids. The spores germination give rise to the riiccia. The plant body of Riccia is gametophytic and gametophytes are fleshy, prostrate and dichotomously branched.
Life cycle of riccia
The second division is at right angle to the first and results in the formation of four cells. Majority of the species of this genus are terrestrial but some species are aquatic as these are found growing actually in the water.
Mature antherozoids remain free in the semifluid substance in the antheridial cavity. Many rhizoiu develop later on from the multicellular thallus and fix it on the soil Fig.
We think you have liked this presentation. The spores are tetrahedrally arranged Fig. The mature antherozoids along with semifluid mass, come out of the antheridium to the antheridial chamber and then to the dorsal surface of the thallus. Rhizoids are numerous, unicellular, elongated, tubular and hair-like and are found as simple rhizoids or tuberculate rhizoids.
Apical cells of the antheridial wall get swollen by absorbing water. The mature sporogonium in Riccia is of very simple structure. The thallus of Riccia has a simple structure and is formed of parenchymatous cells which are bounded on both sides by the upper and lower epidermis. The newly formed young gametophyte cydle enclosed with in the old gametophyte Fig.
The lowermost cell layer rccia this zone forms the lower epidermis. Neck of the archegonium consists of six vertical rows and each row consists six to nine cells.
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One flagellum serves for propulsion and the other for rotation and for changes in direction Fig.