rav65819_ch36_717-740

rav65819_ch36_717-740 - ; part VI plant form and function...

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;;;;;;;;; part VI plant form and function 36 chapter
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Plant Form introduction ALTHOUGH THE SIMILARITIES AMONG a cactus, an orchid, and a hardwood tree might not be obvious at first sight, most plants have a basic unity of structure. This unity is reflected in how the plants are constructed; in how they grow, manufacture, and transport their food; and in how their development is regulated. This chapter addresses the question of how a vascular plant is “built.” We will focus on the cells, tissues, and organs that compose the adult plant body. The roots and shoots that give the adult plant its distinct above- and below-ground architecture are the final product of a basic body plan first established during embryogenesis, a process we will explore in detail in this chapter 36.3 Roots: Anchoring and Absorption Structures Roots are adapted for growing underground and absorbing water and solutes ModiFed roots accomplish specialized functions concept outline 36.1 Organization of the Plant Body: An Overview Vascular plants have roots and shoots Roots and shoots are composed of three types of tissues Meristems elaborate the body plan throughout a plant’s life 36.2 Plant Tissues Dermal tissue forms a protective interface with the environment Ground tissue cells perform many functions, including storage, photosynthesis, and support Vascular tissue conducts water and nutrients throughout the plant 36.4 Stems: Support for Above-Ground Organs Stems carry leaves and flowers and support the plant’s weight ModiFed stems carry out vegetative propagation and store nutrients
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36.5 Leaves: Photosynthetic Organs External leaf structure reflects vascular morphology Internal leaf structure regulates gas exchange and evaporation ModiFed leaves are highly versatile organs 717 rav65819_ch36_717-740.indd 717 rav65819_ch36_717-740.indd 717 12/8/06 2:51:28 PM 12/8/06 2:51:28 PM 36.1 Organization of the Plant Body: An Overview As you learned in chapter 30, the plant kingdom has great diversity, not only among its many phyla but even within species. The earliest vascular plants, many of which are extinct, did not have clear differentiation of the plant body into specialized organs such as roots and leaves. Among modern vascular plants, the presence of these organs reflects increasing specialization, particularly in relation to the demands of a terrestrial existence. Obtaining water, for example, is a major challenge on land and roots are adapted for water absorption from the soil. Leaves, roots, branches, and flowers all exhibit variations in size and number from plant to plant. The development of the form and structure of these parts may be precisely controlled, but some aspects of leaf, stem, and root development are quite flexible. This chapter emphasizes the unifying aspects of plant form, using the flowering plants as a model.
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This note was uploaded on 10/15/2010 for the course BIO BIO1 taught by Professor Lipke during the Fall '09 term at CUNY Brooklyn.

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rav65819_ch36_717-740 - ; part VI plant form and function...

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