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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Lufe Museum of Natural History. Reproduction in Riccia With Diagram. Ricdia favourable conditions it develops into a new thallus. Primary antheridial cells divide by two successive vertical divisions at right angle to each other to form two tiers of four cells each Fig. Fertilization ends the gametophytic phase. It again divides by a transverse division which is parallel to first division. 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.
The wall of each mature spore is very unevenly thickened and ot consists Pf three layers, the outer exosporium which is thin, hard and cutinised; the middle mesosporium which is very thick and soft; and the inner endosporium which is membranous. Both flagella resemble morphologically but differ in function.
In terrestrial species thallus bears many rhizoids and small, colourless or violet scales near the apex Fig. The scales are multicellular and hyaline glassy in appearance, or violet due to the pigment anthocyanin.
When a lufe falls on a suitable place, it germinates by the production of a long tube. All the cells of the photosynthetic filament except the uppermost one are isodiametric and possess many discoid chloroplasts. A transverse division takes place in all the cells resulting in the production of a lower and an upper group of cells. Each air chamber is bounded by four epidermal cells e.
The next division is also vertical but it is at right angle to the first. Mosses and liverworts of Britain and Ireland: Lifd consists of upper elongated slender neck and basal globular portion called venter.
As all stated the mature spores are released by the bursting of this wall after a long lif when the tissue of the thallus has decayed.
Life Cycle of Riccia (With Diagram) | Hepaticopsida
California it is 9 Siler, The lower storage region is a continuation of the cylce assimilatory region and is parenchymatous. The cells of the amphithecium divide only by anticlinal division to form a single-layered sterile jacket or capsule wall. The calyptra layer is a part of gametophyte. Published by Darrell Bradley Modified over 2 years ago.
The spores are tetrahedrally arranged Fig.
Apical cells of the antheridial wall get swollen by absorbing water. The wall of the antheridium consists of a single layer of cells and encloses a mass of androcytes or antherozoid mother cells. Each androcyte thus metamorphosis into an antherozoid Fig. He considered these cells as the fore-runnes of elaters found in higher forms of Marchantiales.
Views Read Edit View history. It remains attached to the thallus by a short stalk.
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After meiosis the mass of spores lies free in the outer layer of calyptra and mature sporogonium has no diploid structure. According to Pagansome of the spore mother cells in Riccia crystallina fail to produce ricciia and form abortive nutritive cells called nurse cells. Scales are violet coloured, multicellular and one celled thick structures Fig.
In monoecious species alternate groups of antheridia and archegonia develop at a sufficient distance from the growing point.
Riccia – Wikipedia
Lice are numerous, unicellular, elongated, tubular and hair-like and are found as simple rhizoids or tuberculate rhizoids. The oospore increases very much in size filling the whole cavity of the venter. It consists of numerous unbranched photosynthetic filaments arranged in vertical rows with a single row of cells, ending in the upper epidermis.
It consist of only a capsule, missing both foot and seta, and does not perform photosynthesis. 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 contents of each androcyte are transformed into an antherozoid. In the meantime the axial cell by a transverse division has divided into an upper neck canal initial and a lower central cell.
Depending on species, the thallus may be strap-shaped and about 0. They are haploid uninucleate and pyramidal in shape Fig. The thallus is branched and or a dorsal median groove and ventral median ridge. It is the most common method of vegetative reproduction in Riccia. The main function of rhizoids is to anchor the thallus on the substratum and to absorb water and mineral nutrients from the soil. Ricciaceae Marchantiales genera Bryophyte stubs. In hygrophilous species species which need a large supply of moisture for their growth the scales are ephemeral i.
The venter contains a lower larger cell, cyccle egg or oosphere, and a smaller upper cell known as the ventral canal cell. Antheridial chamber, in which an antheridium lies, communicates with the clorsal surface of the thallus by terminal opening.
It has a single-layered capsule wall which encloses spores. 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.
The dorsal surface is light green or dark green body, each branch having a thick midrib. Basal cell remains embedded in the tissue of thallus, undergoes only a little further development and forms the embedded portion of the antheridial stalk.