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LEPIDODENDRON

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Lepidodendron: Habit and Habitat of Lepidodendron: A new groups of arborescent lycopods, popularly known as Lepidodendrales, had evolved from the Middle Devonian lycopods. These arborescent plants would grow to 164 ft (50 m) and form extensive coal measures swamp forest of the Northern Hemisphere Euramerican province during the Carboniferous period. Among these, Lepiclodendron was the most successful of all the arborescent members and is the best-investigated genus (Fig. 7.36). In early stage of development, an endosporic prothallus grew straight up and subsequently it expanded its diameter by secondary growth until its apical meristem divided. Thus, in the successive dichotomy, the size of the branches decreased until the growth finally ceased with terminal twig. So the plant had a determinate growth pattern. The Lepidodendron was a large tree (50-60 m tall) with a prominent trunk (up to 35 m height). The ultimate dichotomies formed the leaves. The branches and the foliage
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A fossil Pteridophyta; RHYNIA

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RHYNIA; The fossil Pteridophyta Above: Transverse sections through axes of Rhynia gwynne-vaughanii . The star-shaped axes, right of centre, are a result of shrinkage during decay and desiccation of the stems (scale bar = 1mm).   Introduction One of the first Rhynie chert plants to be described and perhaps the most abundant is the form Rhynia . The plant was originally described and classified by Kidston and Lang in 1917 , 1920a and assigned the species name Rhynia gwynne-vaughanii . Another plant now known as Aglaophyton , possessing a slightly similar anatomy, was originally described by Kidston and Lang in their 1917 paper as also belonging to Rhynia gwynne-vaughanii , but differs significantly in its vascular anatomy and was subsequently reassigned (see also Aglaophyton ). Unequivocal gametophytes of Rhynia have recently been discovered ( Kerp et al . in press ) and will be illustrated here once published. The overall
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Different functional systems of PIGEON

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Pigeon The following points highlight the top nine types of system in pigeons. The types are: 1. Muscular System 2. Digestive System 3. Respiratory System  4. Circulatory System  5. Lymphatic System  6. Nervous System  7. Endocrine System  8. Excretory System  9. Reproductive System. Type # 1. Muscular System : The muscular system of pigeon is extreme­ly modified to meet the requirements of its peculiar way of life. The muscles of the active regions, i.e., breast and wings, legs, neck, tail are highly developed, whereas in the compa­ratively immobile regions, partly the back muscles become atrophied. Some muscles in pigeon’s body have changed their function due to the modifications for flight. The myo­fibrils composing the muscles are extremely elongated and they can withstand fatigueless during prolonged activity. There are many muscles in pigeon, of which the following muscles, connected with the activities of the   wings and legs, are described below: Breast and Wi
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