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PORELLA

Occurrence It grows on moist rocks. It also occurs on shaded sides of tree trunks. It forms dense mats closely covering the substratum. Some are aquatic and grow in cool waters. General structure Plant body is gametophyte. It is composed of three parts: I.  Stem: The mature plant consists of a slender dorsoventral stem. it branches extensively. The prostrate stems ...

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POLYTRICHUM

Occurrence Polytrichum have worldwide distribution. They are very common in cool temperature and tropical regions. Plants live in cool and shady places. General structure The main plant body is gametophyte. The adult plant consists of two parts: rhizome and upright leafy shoot. 1.  Rhizome: It is horizontal portion and grows underground. It bears three rows of small brown or colourless ...

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Funaria

Funaria Occurrence Funaria is  terrestrial moss. It grows in the form of bright green velvety patches in shady and damp places. Genus Funaria is composed of 117 species. Funaria hygrometrica is most common and worldwide species. It grows well on burnt soil. It grows best in the presence of calcium, potassium, nitrogen and phosphorus. Vegetative structure of gametophyte Structure of ...

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fossils

Fossil & Fossilization – importance , types and divisions PALEOBOTANY The study of fossils of plant life of the geologic past is called paleobotany. Paleobotany tells us the story of preserved vestiges of the plant life of the past. In simplified language paleobotany may be defined as a branch of botany which deals with the study of such plants which ...

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pteridophytes

Occurrence and evolution of Pteridophytes Pteridophyta is a group of ancient plants. They formed the dominant part of the earths during Palaeozoic and Mesozoic periods. Majority of Pteridophytes became extinct. They are preserved in the form of fossils or coal deposits. Only a few living Pteridophyta are left. General structure The vegetative plant body is a sporophyte in Pteridophytes. Sporophyte ...

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Photoperiodism

Photoperiodism Photoperiodism is the response of a plant to the relative length of light and dark periods to produce flower. The relative length of day and night to which a plant is exposed is called the photoeriod. Photoperiodism is a photobiological process – a process that involves absorption of light by a receptor (usually a pigment) that results in activation ...

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Psilopsida Botany-Leptosporangiate fern

PSILOPSIDA TYPE PSILOTUM Occurrence Psilotum is distributed in tropical and subtropical regions. It may grow as an epiphyte on the bark of trees. It also grows on soil where humus is abundantly available. General structure The plant body is sporophyte. The plant is a small shrub. The plant body is differentiated into rhizome and aerial branches. 1.  Rhizome: Rhizome is ...

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Theories of ascent of SAP

Here are following theories which explain the ascent of sap in plants: a) Root pressure (b) Capillarity (c) Vital theory and (d) Cohesion-tension theory. (a) ROOT PRESSURE The hydrostatic pressure generated in the root which forces the water upward in the stem is called root pressure. Root pressure forces the water up from below. But it is believed that root ...

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SEX DETERMINATION

SEX DETERMINATION The chromosomes which determine sex in the different organisms are called sex chromosomes. ‘Fhe term –sex– refers to the processes that enable species to exchange materials between homologous chromosomes. Ii causes recombination. Recombination is essential to their mechanism for reproduction. Work on inheritance of sex started after discovery of Menders ork in 1900. The discovery of sex chromosomes ...

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Epidermis

EPIDERMIS Epidermis forms the outermost layer of cells on the primary plant body. It is present over stem. roots, leaves, flowers and fruits. In most plant. epidermis is composed of single layer of cells. But two or several layers are also found in different plants. When it is composed of single layer, it is called hypodermis. When it is composed ...

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