Comparative Study of Bryophyte Sporophytic Generation PDF

# Comparative account of the sporophytes of Riccia, Marchantia, Anthoceros, Notothylas, Sphagnum, Polytrichum and Funaria ## Structure | Species | Sporophyte Structure | |---|---| | Riccia | Globose capsule without foot and seta, fully embedded within gametophytic tissue. | | Marchantia | A bulbou...

# Comparative account of the sporophytes of Riccia, Marchantia, Anthoceros, Notothylas, Sphagnum, Polytrichum and Funaria ## Structure | Species | Sporophyte Structure | |---|---| | Riccia | Globose capsule without foot and seta, fully embedded within gametophytic tissue. | | Marchantia | A bulbous or anchor-shaped foot, a more or less long and thick seta, and a spherical or oval capsule. | | Anthoceros | A mature sporophyte is differentiated into an expanded bulbous foot and a long cylindrical capsule; seta is absent. | | Notothylas | Sporophyte is differentiated into a triangular foot and a cylindrical capsule. | | Sphagnum | Sporophyte is differentiated into a small conical foot, a long slender seta and an angular capsule. | | Polytrichum | Sporophyte is differentiated into a poorly developed conical foot, a long, more or less twisted seta and a pear-shaped bent asymmetrical capsule. | | Funaria | Sporophyte is differentiated into a poorly developed conical foot, a long, more or less twisted seta and a pear-shaped bent asymmetrical capsule. | ## Capsule Wall | Species | Capsule Wall | |---|---| | Riccia | The capsule is provided with a sterile jacket wall composed of single layer of abortive cells, within which lie sporocytes (spore mother cells) and sometimes few abortive nurse cells; elaters are absent. | | Marchantia | Capsule wall i.e. jacket is single layered and persistent, within wall lie sporocytes and long, narrow, spindle-shaped sterile cells with two spiral thickenings known as elaters. | | Anthoceros | Capsule wall i.e. jacket is single layered and persistent, within wall lie sporocytes and long, narrow, spindle-shaped sterile cells with two spiral thickenings known as elaters. | | Notothylas | Capsule wall is multilayered i.e., consists of 4-6 layers of cells -the outermost layer with stomata, wall cells are chlorophyllous. Next to wall lies sporogenous tissue which is differentiated into alternate blocks of sterile pseudoelaters without thickenings and also lack chlorophyll. | | Sphagnum | Capsule wall is several cell layers (4-6), outer layer is provided with stomata. Capsule apex bears disc shaped circular operculum which is thick and persistent, contain chlorophyll. | | Polytrichum | Capsule wall is several cell layers of cells composed of colourless parenchyma cells. Capsule apex shows a dome-shaped operculum without beak. | | Funaria | Capsule wall is 3-4 layered, persistent-composed of colourless parenchyma cells. Capsule apex shows a dome-shaped operculum without beak. | ## Development | Species | Development | |---|---| | Riccia | Amphithecium gives rise of jacket of capsule and endothecium to sporogenous tissue (archesporium) which later on differentiates into sporocytes and few nurse cells. Mature capsule has no true jacket-the so-called jacket is the outer layer of the venter. | | Marchantia | Amphithecium gives rise to jacket of the young capsule and endothecium to sporogenous tissue (archesporium) which later on differentiates into sporocytes and few nurse cells. Mature capsule has no true jacket-the so-called jacket is the outer layer of the venter. | | Anthoceros | Amphithecium gives rise to jacket of the capsule and sporogenous tissue (archesporium) and endothecium to sterile columella. | | Notothylas| Amphithecium gives rise to jacket of the capsule and sporogenous tissue (archesporium), while endothecium gives rise to sterile columella. | | Sphagnum | Amphithecium gives rise to jacket of the capsule and sporogenous tissue (archesporium), and endothecium gives rise to sterile columella. | | Polytrichum | Amphithecium gives rise to jacket of capsule, and endothecium gives rise to sporogenous tissue (archesporium) and endothecium gives rise to sterile columella. | | Funaria | Amphithecium gives rise to jacket of capsule, and endothecium gives rise to sporogenous tissue (archesporium) and endothecium gives rise to sterile columella. | ## Mode of life | Species | Mode of life | |---|---| | Riccia | There is no chlorophyllous tissue in the sporophyte, it is entirely parasitic on gametophyte. | | Marchantia | There is no chlorophyllous tissue in the sporophyte, it is entirely dependent on gametophyte. | | Anthoceros | At the base of capsule meristematic tissue is present, capsule wall also contains chlorophyllous tissue; Stomata are present. | | Notothylas | Amphithecium gives rise to jacket of the capsule and sporogenous tissue (archesporium), while endothecium gives rise to sterile columella. But in non-columellate species, the entire amphithecium forms the capsule wall and the entire endothecium produces the archesporium. | | Sphagnum | Sporophyte has no chlorophyllous tissue, hence it is partly autophytic. | | Polytrichum | Sporophyte has no chlorophyllous tissue, hence it is partly autophytic. | | Funaria | Sporophyte has no chlorophyllous tissue, hence it is partly autophytic. | ## Dehiscence mechanism | Species | Dehiscence mechanism | |---|---| | Riccia | Dehiscence mechanism is absent, spores are simply liberated by the death and decay of the jacket wall of the capsule and the surrounding tissue of thallus. | | Marchantia | Dehiscence mechanism is present, the capsule wall splits longitudinally into irregular number of lobes exposing spores upon columella-sp-copic movement help in spore dispersal. Elaters by hygroscopic movements help in spore dispersal.| | Anthoceros | Dehiscence mechanism is present, the capsule wall splits into two valves regularly exposing spores upon columella-sp-copic movement help in spore dispersal. Elaters by hygroscopic movements help in spore dispersal.| | Notothylas | Dehiscence mechanism is present which is like a follicle along one suture only, sometimes by both sutures. Spore dispersal takes place by air current. | | Sphagnum | Dehiscence mechanism is present, and which takes place by the separation of operculum violently ejecting thereby cloud of spores. | | Polytrichum | Dehiscence of capsule takes place by the separation of operculum. Then drying up of thin-walled cells between the peristome teeth takes place, as a result small openings are formed in the margin of the epiphragm through which spores are liberated, a few at a time when the capsule sways by wind. | | Funaria | Dehiscence of capsule takes place by the separation of operculum. Then drying up of thin-walled cells between the peristome teeth takes place, as a result small openings are formed in the margin of the epiphragm through which spores are liberated, a few at a time when the capsule sways by wind. | ## Conclusions | Species | Conclusion | |---|---| | Riccia | Riccia sporophyte is the simplest type as the structure is represented by a capsule only without any foot and seta; moreover the sporophyte is entirely embedded within the gametophytic tissue for the nourishment as the true jacket with chlorophyllous tissue absent. Sporogenous tissue is not reduced, most of the cells of sporogenous tissue become spore mother cells:. only a few become sterile (nurse cells) which are looked upon as forerunners of elaters. Dehiscence of capsule is absent. | | Marchantia | Marchantia sporophyte is much more advanced than Riccia because, (a) sporophyte is differentiated into foot, seta and capsule, (b) capsule is protected by pseudo-perianth, (c) sterile portions are much greater-the jacket is multilayered with chlorophyll containing cells and stomata on the outer surface. (d) dehiscence of capsule by valves and scattering of spores by means of elaters are present. | | Anthoceros | Anthoceros highest complexity in the organization of the sporophyte is reached among bryophytes because, (a) sporophyte is differentiated into capsule and foot; (b) sterile portions are much greater-the jacket is multilayered with chlorophyll containing cells and stomata on the outer surface. (c) presence of meristematic tissue at the base of capsule, by the activity of which sporophyte can grow independently, (d) sporogenous tissue is much more reduced due to alternate breaking into spore-tetrad and elaters, (e) capsule dehisces regularly into 2 valves. (f) presence of centrally situated sterile columella which is forerunner of vascular strands of pteridophytes. | | Notothylas | Notothylas exhibits controversial evolutionary trend. Notothylas is considered as a link between liverworts and Anthocerotales. Notothylas is a primitive genus from which Anthoceros has evolved by the process of progressive evolution. | | Sphagnum | Sphagnum sporophyte is also advanced type than previous types except Anthoceros because the capsule has multilayered chlorophyllous jacket cells, though elaters are absent still sporogenous tissue is much more reduced, and sterile columella is present. Regular dehiscence of capsule is also present. | | Polytrichum | In Polytrichum the sporophyte has also reached complexity in comparison to Riccia and Marchantia except Anthoceros. Not only the sporophyte has foot, seta and capsule but in the capsule sterile portions are much greater-the jacket is multilayered with chlorophyll containing cells and stomata on the outer surface. (c) the process of progressive evolution has further advanced in this genus. The process of dehiscence has been developed in the presence of air space, operculum, peristome teeth etc., large sterile columella is also present; presence of limited sporogenous tissue with all its protective investments-these show tendency of advancement at the time of evolution. | | Funaria | In Funaria, the sporophyte has also reached complexity in comparison to Riccia and Marchantia except Anthoceros. Not only the sporophyte has foot, seta and capsule but in the capsule sterile portions are much greater-the jacket is multilayered with chlorophyll containing cells and stomata on the outer surface. (c) the process of progressive evolution has further advanced in this genus. The process of dehiscence has been developed in the presence of air space, operculum, peristome teeth etc., large sterile columella is also present; presence of limited sporogenous tissue with all its protective investments-these show tendency of advancement at the time of evolution. |