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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Some species of Riccia like R. Air pores occasionally break through the dorsal surface, giving the thallus a dimpled appearance. The scales are multicellular and hyaline glassy in appearance, or violet due to the pigment anthocyanin.
Scales are arranged in a transverse row and may be membranous, multicellular, single celled, and with colours ranging from pink, red, violet and black. The venter contains a lower larger cell, the egg or oosphere, and a smaller upper cell known as the ventral canal cell.
Each androcyte thus metamorphosis into an antherozoid Fig. 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.
Life Cycle of Riccia (With Diagram) | Hepaticopsida
Simultaneously the primary axial small cell divides transversely and unequally to form small upper primary cover cell and large lower central cell Fig. In monoecious species alternate groups of antheridia and archegonia develop at a sufficient distance from the growing point. The androcyte soon looses its triangular shape and becomes somewhat round or oval Fig.
Each androcyte has a prominent nucleus and a small extra-nuclear granule called blepharopiast. This gamete producesmale antherozoids and female oosphere gamete surrounding vegetative tissue. Antheridium is present singly in an antheridial chamber.
These cells become softened and finally breakdown to release mass of antherozoids. They develop as prolongations of the lower epidermal cells. The colour of the scale is due to dissolution of the pigment in the cell sap.
OK Moss Life Cycle. Sexual reproduction in Riccia is oogamous. Primary stalk cells form the stalk of the antheridium.
Riccia Ms. Inderveena Sharma H.O.D. Botany Department – ppt video online download
Some cells of the lower epidermis extend to form the scales and both types of rhizoids. The development of antheridium starts from a superficial antheridial cell, situated on the dorsal surface of the thallus Fig.
Its blepharoplast elongates into a cord and occupies about two-thirds of its part. A vertical cross section of the thallus shows two distinct zones, viz.
Riccia – Wikipedia
It cuts a number of cells on its left and right side to form the multicellular thallus Fig. Simultaneously the nucleus also becomes crescent shaped, homogeneous and ultimately comes in contact with the blepharoplast. Chinese Company introduces new low price Chinese electric car in Pakistan. 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.
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. Plants are usually monoicousand sexual reproduction is by antheridia and archegonia.
On resumption of favourable conditions tubers produce new thalli. These are capable to pass on the unfavorable conditions. Sex organs riccis in acropetal succession i.
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The terminal cells of photosynthetic filaments are large, hyaline and form loose, ill-defined and discontinuous one celled thick epidermis.