LIFE CYCLE OF RICCIA PDF
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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On resumption of favourable conditions tubers produce new thalli. Each branch of the thallus is linear, wedge-shaped or obcordate. A deep cleft or furrow is commonly present in the middle of each lobe on the dorsal side; the sex organs are found embedded in this furrow. The storage region is formed of compactly arranged parenchymatous cells which are either colourless or contain only few chloroplasts, but these cells are rich in starch grains. Formation of rhizoids is affected by light intensity.
As water enters in their antheridial chamber, the sterile apical cells of the antheridial jacket enlarge by absorbing water, become softened and ultimately break open. The central cell divides Producing an egg or oosphere towards the base and a small ventral canal cell towards the upper side.
Thallus is mm long and 1. The basal or the posterior part of the thallus starts rotting or disintegrating due to ageing or drought. A mature antheridium has a short stalk and oval shaped body with a flat base and conical apex Fig. 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 tissue which may take even a year or so after the maturation of spores.
life cycle of riccia –
A vertical cross section of the thallus shows two distinct zones, viz. In certain species R. The archegonia, like the antheridia, are also embedded in the mid-dorsal furrow of the thallus and are arranged in acropetalous order i.
The capsule wall and inner layer of calyptra break down before the spore mother cells divide to form the spores. The next division is also vertical but it is at right angle to the first. Towards the end of the growing season the apices of the thallus lobes get thickened and form the perennating tubers.
Light, low temperature and water is essential for spore germination. The development of the archegonium starts on the dorsal surface of the thallus from a single superficial ccyle, which acts as an archegonial initial Fig.
Riccia Ms. Inderveena Sharma H.O.D. Botany Department
Rhizoids are numerous, unicellular, cyclw, tubular and hair-like and are found as simple rhizoids or tuberculate rhizoids. It is made of somewhat vertical rows of un-branched photosynthetic filaments.
Rhizoids develop in the light medium intensity. The price of the …. 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 crowded growth of the various lobes is due to the repeated dichotomies of the thallus The thallus lobes arc flat growing horizontally on the soil and each lobe has a small not that the apex where the growing point is situated.
At the end it divides by a transverse division to form a small cell Fig. This bryophyte -related article is a stub. Each spore mother cell produces the four spore the unsual method after the reduction division of its nucleus, spore mass is enclosed in the outer layer and not by the sporogonium wall lofe has disorganised. Stalk attaches the antheridium to the base of the antheridial or. In spongy thallus of Riccia crystallina the assimilatory or photosynthetic cells form a loosely- arranged network enclosing large air spaces.
The ventral surface of thallus bears many scales and rhizoids. Some cells of the lower epidermis extend to form the scales and both types of rhizoids. This species can also grow on soil. This page cylce last edited on 16 Octoberat One flagellum serves for propulsion and the other for rotation and for changes in direction Fig. There are no elaters.
Botany Department”— Presentation transcript: For the Italian “comune”, see Riccia, Molise. Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top. Riccia plants may be monoecious or dioecious depending upon the species.
Male reproductive bodies are known as antheridia and female as archegonia. It is more a method of perennation rather than multiplication.
Each archegonium develops from a superficial cell situated on the dorsal side about three or four cells away from the growing point. Sex organs lie embedded in the mid dorsal section of the thallus between air spaces ricica filaments. Air pores occasionally break through the dorsal surface, giving the thallus a dimpled appearance.
Riccia belongs to the family Ricciaceae of lfie order Marchantiales. Both the androcytes remain enclosed in the wall of the androcyte mother cell with one separate cyce Fig. This article is about the plant Riccia. Rhizoids are unicellular and un-branched. The cells of the upper epidermis are also loosely placed having spaces cucle between them which function as pores through which the underlying air spaces communicate out for the exchange of gases.
Riccia Ms. Inderveena Sharma H.O.D. Botany Department – ppt video online download
In hygrophilous species species which need a large supply of moisture for their growth the scales are ephemeral i. Gives structural support less affected by gravity. Chinese Company introduces new low price Chinese electric car in Pakistan.