Gametophyte Of Funaria
Useful Notes on Anthocerotopsida Order Anthocerotales 4. WordsHere are your useful notes on Anthocerotopsida The class Anthocerotopsida Anthocerotae consists of a single order, the Anthocerotales and a single family, the Anthocerotaceae, 6 genera and 3. According to Muller 1. Reimers 1. 95. 4 and Proskauer the order Anthocerotales includes two families, i Anthocerotaceae and ii Notothylaceae. The latter includes a single genus, i. Notothylas. However, according to top bryologists, there is only one family, i. Anthocerotaceae. About five or six genera are included in this family. Image Courtesy upload. Phaeoceroslaevis. These genera areAnthoceros, Phaeoceros, Aspiromitus, Notothylas, Dendroceros and Megaceros. Gametophyte Of Funariaceae' title='Gametophyte Of Funariaceae' />RESOURCES FOR QUEENSLAND STUDENTS TEACHERS DEADLY EEI IDEAS Ideas for Year 11 and 12 Biology Extended Experimental Investigations. From Dr Richard Walding, BAppSc. Retrouvez toutes les discothque Marseille et se retrouver dans les plus grandes soires en discothque Marseille. Four genera are universally recognised, they areAnthoceros, Megaceros, Dendroceros and Notothylas. This group differs in many respects from the other Bryophyta. However, the group is placed intermediate between Hepaticopsida Hepaticae and Bryopsida Musci. The group is considered to be very important from the point of view of its morphology, because of its intermediate position between the two important groups, the Hepaticopsida and Bryopsida. The most characteristic features of the group are as follows The gametophytic plant body is thalloid and dorsiventral. The rhizoids are simple and smooth walled. Tuberculate rhizoids and ventral scales are altogether absent. The tissues of the thallus are not differentiated. Air chambers and air pores are absent. Each cell of the thallus possesses a large chloroplast and a conspicuous pyrenoid within it. The antheridia are endogenous, i. The antheridia are developed within the antheridial chambers, singly or in groups on the dorsal side of the thallus. The archegonia are found in sunken condition on the dorsal side of the thallus. The sporogonium arises from the dorsal side of the thallus. It is elongated and cylindrical in structure. It consists of foot, meristematic region and capsule. It possesses intercalary meristem, and continues its growth throughout the growing season. The wall of sporogonium contains chlorophyll. The central sterile portion is columella, which is surrounded by sporogenous tissue and spores. The elaters are also present. The sporogenous mass develops from amphithecium and arches over the columella. Family Anthocerotaceae There are five genera i. Consider the following four statements whether they are correct or wrong a The sporophyte in liverworts is more elaborate than that in mosses. Gametophyte Of Funaria DiagramAnthoceros, Phaeoceros, Aspiromitus, Dendroceros and Megaceros in this family. Characteristic features The sporogonium capsule is linear and vertical. Generally the stomata are present on capsule wall. The archesporium arises from amphithecium. The elaters are four celled, smooth or thick walled and with or without thickening bands. The genus Anthoceros has been discussed here in detail. Genus ANTHOCEROS Habitat and distribution About 2. The species are moist and shade loving. About 2. 5 species have been reported from India, by various workers. The three common Himalayan species are, Anthoceros himalayensis, A. A. chambensis. The above mentioned species are common in various hilly regions such as, Mussoorie, Kumaon hills, Chamba valley and other places, 5,0. Some species have been reported from South India. All the species are found in very shady and moist places. They are found in the hollows of the moist rocks in dense patches. According to Cavers 1. The species, are not at all drought resistant. External structure of the thallus The thallus is small, prostrate, dark green and dorsiventrally differentiated. The thallus is lobed and the lobes are somewhat divided. The mid rib is not found. The dorsal surface of thallus of A. A. crispulus Bhardwaj, 1. A. fusiformis. In every case the smooth walled, simple rhizoids are found. The ventral scales and tuberculate rhizoids are altogether absent. The thalli are dark green, because of the presence of the Nostoc colonies, which may be easily seen with the help of lens from the underside of the thallus. Internal structure of the thallus The anatomy of the thallus is quite simple. Internal to the upper and lower epidermis there are simple, parenchymatous cells. The cells of parenchyma are isodiametric and uniform. Air chambers and air pores are absent. Each cell contains a big chloroplast which possesses a single pyrenoid in its centre. The chloroplasts are lens shaped. Autocad Lt 2000I'>Autocad Lt 2000I. The chloroplasts of the superficial cells are longer than the chloroplasts of the other cells. According to Mc. Allister 1. Anthoceros are quite different in structure from those of Chlorophyceae. On the ventral side of the thallus certain intercellular mucilage cavities are found. These cavities open by small openings, the slime pores on the ventral surface of the thallus. Sometimes, the colonies of blue green algal form Nostoc, are found in the mucilage cavities. There is no symbiotic relationship between these Nostoc, colonies, and thalli. According to Peirce 1. The nucleus lies in the close vicinity of the chloroplast, near the pyrenoid. Sometimes the chloroplast enfolds the nucleus within it. Apical growth The apical growth of Anthoceros is a controversial topic, whether it takes place by a single apical cell or by a group of apical cells. According to Smith 1. According to Leitgeb 1. Alternative Learning System Program. According to Mehra and Handoo 1. Anthoceros erectus and A. Reproduction The reproduction takes place by means of 1 vegetative and 2 sexual methods. Vegetative reproduction The vegetative reproduction takes place by various ways. By progressive growth and death of thallus The vegetative propagation takes place by progressive growth and death of the older part of the thallus reaching dichotomy. But this method is not so common in Anthoceros as in Riccia and Marchantia. By tubers In certain species of Anthoceros, the thallus becomes thickened at several places on the margins. Such marginal thickenings are called, the tubers. These tubers are perennating structures. They survive in the drought conditions. On the advent of the favourable conditions, they develop into new thalli. The tubers are formed in A. A, tuberosus, A hallii, A. A. himalayensis. c By gemmae In some of the species of Anthoceros, the gemmae have been found. The gemmae have been recorded from the species, A. A. formosae, etc. Each such gemma develops into a new thallus. By persistent growing apices According to Campbell the thalli of the species A. A. fusiformis become completely dried up in summers, leaving growing apices with adjacent tissues. These apices face the drought conditions. On the approach of favourable conditions, these apices develop into new thalli. Sexual reproduction The species of Anthoceros may be homothallic monoecious or heterothallic dioecious. Some of the homothallic species are A. A. punctatus, Kashyap 1. A. himalayensis as a dioecious heterothallic species, but Mehra and Handoo 1. The heterothallic species are, A. A. halli, A. erectus and others. The sex organs, i. Development of antheridium The antheridia are produced singly or in groups in the antheridial chambers. The development is endogenous. Though the antheridium develops from a superficial cell, yet it is enclosed within the antheridial chamber which does not open out by any opening. A dorsal superficial cell of the thallus, situated near the growing apex divides periclinally giving rise to two daughter cells. According to Cavers, Campbell and Haupt the superficial cell divides transversely and not periclinally. The upper daughter cell acts as roof initial and the lower one as antheridial initial.