Biological Sciences
Vascular Plants
Vascular plants are a group of plants that have specialized tissues for transporting water, nutrients, and sugars throughout the plant. These tissues, called xylem and phloem, allow vascular plants to grow larger and more complex than non-vascular plants. Vascular plants include a wide variety of species, from small ferns to towering trees, and are essential components of terrestrial ecosystems.
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5 Key excerpts on "Vascular Plants"
eBook - PDFBiology
Concepts and Applications
- Cecie Starr, Christine Evers, Lisa Starr, , Cecie Starr, Christine Evers, Lisa Starr(Authors)
- 2017(Publication Date)
- Cengage Learning EMEA(Publisher)
CREDITS: (in text) left column from the top, © Kingsley R. Stern; Biodisc/Visuals Unlimited/Corbis; Dr. Keith Wheeler/ Science Source; Forestry and Forest Products Research Institute, Japan; Spike Walker/Wellcome Images; (4) bottom, Andrew Syred/Science Source. Figure 25.4 Cells that make up plant vascular tissues. Xylem and phloem are vascular tissues. Both consist of cells that make up conducting tubes bundled with fibers and parenchyma. B Tracheid A Vessel C Sieve tube ? FIGURE IT OUT What are the green structures in the cells surrounding the vascular tissues? Answer: Chloroplasts 427 C H A P T E R 2 5 PLANT TISSUES Copyright 2018 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. WCN 02-300 INTERNAL STRUCTURE Stems form the basic framework of a flowering plant, providing support and keeping leaves positioned for photosynthesis. They can grow above or below the soil, and in many species they are specialized for storage or asexual reproduction. Stems characteristically have nodes, which are regions of the stem where leaves attach. New shoots (and roots) can form at nodes. Xylem and phloem are organized in long, multistranded vascular bundles that run lengthwise through a stem. The main function of vascular bundles is to conduct water, ions, and nutrients between different parts of the plant. Some components of the bundles—fibers and the lignin-reinforced walls of tracheids—also play an important role in supporting upright stems of Vascular Plants. Vascular bundles extend through the ground tissue of all stems and leaves, but the arrangement of the bundles differs between monocots and eudicots. In monocot stems, vascular bundles are typically distributed throughout the ground tissue (Figure 25.5A). By contrast, a typical eudicot stem has all of the vascular bundles arranged in a characteristic ring (Figure 25.5B).
eBook - ePub- (Author)
- 2008(Publication Date)
- Trade Paper Press(Publisher)
stomata; and permanently rolled leaves or leaves that roll up in dry weather (as in marram grass). Many desert cacti are xerophytes.xylem tissue found in Vascular Plants, whose main function is to conduct water and dissolved mineral nutrients from the roots to other parts of the plant.Further Reading
Attenborough, David The Private Life of Plants (1995)Bell, Adrian Plant Form. An Illustrated Guide to Flowering Plant Morphology (1991)Blunt, W . The Complete Naturalist: A Life of Linnaeus (1971)Camus, Josephine; Jeremy, Give; and Thomas, Barry A World of Ferns (1991)Corner, E. J. H . The Life of Plants (1981)Gourlie , N. The Prince of Botanists: Carl Linnaeus (1953)Hall, David Oakley, and Rao, K. K . Photosynthesis (1994)Hecht, Susanna, and Coekburn, Alexander The Fate of the Forest (1989)Heiser, Charles Seed to Civilization (1981)Joyce, Christopher Earthly Goods (1994)Langmead, Clive A Passion for Plants (1995)Lawlor, David W . Photosynthesis: Molecular, Physiological, and Environmental Processes (1993)Lewington, Anna Plants and People (1990)Lewis, Walter, and Elvin-Lewis, Memory Medical Botany. Plants Affecting Man’s Health (1977)Mabberly, David The Plant Book (1990)Mabey, Richard The New Age Herbalist (1988)Page, C. N. The Ferns of Britain and Ireland (1998)Phillips, Roger, and Rix, Martin Vegetables (1995)Prance, Ghillean, and Prance, Anne Bark: The Formation, Characteristics and Uses of Bark Around the World (1993)Proctor, Michael, and Yeo, Peter The Pollination of Plants (1973)Raven, Peter; Evert, Ray; and Eichorn, Susan Biology of Plants (1992)Rudall, Paula Anatomy of Flowering Plants: An Introduction to Structure and Development (1987)Slack, Adrian Carnivorous Plants (1979)Stuessy, Tod Plant Taxonomy (1990)Walker, David Energy, Plants, and Man (1992)Weinstock, J . Contemporary Perspectives on Linnaeus (1985)Zomlefer, Wendy Guide to Flowering Plant Families
eBook - ePub- N. Michelle Holbrook, Maciej A. Zwieniecki(Authors)
- 2011(Publication Date)
- Academic Press(Publisher)
The long distance transport system of plants links the two primary sites of assimilation from the environment, root and leaf. The evolutionary history underlying that simple statement is extremely complex when the full diversity of Vascular Plants over the last 400 million years is taken into account. In the larger context of this volume, stems may be considered primarily as the link between root and leaf, but roots and leaves have each evolved independently in a number of plant lineages, and it is only the stem connecting those termini that can be deemed homologous across the Vascular Plants.Though it is understandable that the angiosperms that dominate the modern world have been the primary focus of physiological investigation, it is important to keep in mind that the period of angiosperm dominance represents only the last quarter of vascular plant history (Wing et al., 1993; Knoll and Niklas, 1987 ). A comparative, evolutionary context can allow assessment of the degree to which results from angiosperm exemplars can be extended to other groups and Vascular Plants as a whole. The fossil record can also point toward living taxa that provide opportunities for physiological comparisons of independently derived but functionally similar structures, such as with roots and leaves.The first Vascular Plants consisted of small, unadorned axes, which were responsible both for photosynthesis and assimilation of water and nutrients. Roots have evolved at least twice (Kenrick, 2002a ; Gensel et al., 2001; Raven and Edwards, 2001 ). The roots found in the lycopod and euphyllophyte lineages (Fig. 23.1 ) have evolved independently and those of freesporing euphyllophytes differ from the seed plants in key respects. Leaves have had an even more complicated history. The lycopods, again, have independently evolved leaves, simple linear structures. Members of the euphyllophyte clade have evolved laminate leaves at least four times (Boyce and Knoll, 2002
eBook - ePubBrilliant Green
The Surprising History and Science of Plant Intelligence
- Stefano Mancuso, Alessandra Viola, Joan Benham(Authors)
- 2015(Publication Date)
- Island Press(Publisher)
Thus plants have a circulatory apparatus that permits the transport of liquids from the bottom to the top and vice versa: a sort of system of arteries and veins, called xylem when the flow goes from bottom to top and phloem when the liquids flow from top to bottom. Xylem (from the Greek xulon, “wood”) is the conductive tissue principally adapted to the transport of water and mineral salts (but also other substances) from the roots to the crown of the plant, while phloem (from the Greek phloios, “cortex”) is the tissue that conducts in the other direction, transporting sugars produced by photosynthesis from the leaves to the fruit and roots. The purpose of this circulation is readily apparent when you consider that the water absorbed by the roots is lost by the leaves in great quantities through transpiration, and so must be continually restored; meanwhile the sugars produced through photosynthesis—the plant’s main source of energy—must be continuously moved from the site of production (the leaves) to other parts of the organism. By means of this complex vascular system, electrical messages circulate smoothly and fairly quickly, as in a tube filled with a conductive solution. Signals that would take a great deal of time to arrive at their destination if transmitted by chemicals can travel in a short time between the roots and the leaves, bringing urgent messages such as those concerning the water status of the soil. Is there only a little water, or a lot? The leaves, with sufficient notice, will adjust to the situation. Figure 4-1. The structure of the stomata (top). By means of these small openings on their surfaces, the leaves take in the carbon dioxide they need for photosynthesis and give off water vapor
eBook - PDF- Rene Fester Kratz(Author)
- 2022(Publication Date)
- For Dummies(Publisher)
• Sclerenchyma cells are similar to collenchyma cells, but their walls are even thicker and reinforced with lignin, a tough molecule found in wood. The cell walls of sclerenchyma cells are so thick, in fact, that mature sclerenchyma cells die because they can’t get food or water across their walls via osmosis (more about osmosis in Chapter 3). » Vascular tissue: You can think of vascular tissue as the plant’s plumbing. The cells within the xylem and phloem link up with one another end-to-end to form long columns of cells that carry nutrients and water up and down the plant. (You can think of these long columns of cells like the pipes of the plant’s plumbing.) • Xylem contains specialized cells called vessels and tracheids. These cells die at maturity, but their cell walls remain intact so that water can continue to flow. Vessel cells are wide and barrel-shaped, while tracheids are slimmer and have pointed ends. • Phloem contains sieve cells for transporting sugars. Sieve cells remain alive but lose their nuclei at maturity as they become specialized for sugar transport. Nearby companion cells retain their nuclei and support the function of the sieve cells. • Vascular tissue also contains parenchyma cells in the vascular cambium, a tissue of cells that can divide to produce new cells for the xylem and phloem. Biologists use the appearance and feel of a plant’s stem to place it into one of two categories: herbaceous (the stem remains somewhat soft and flexible) and woody (the stem has developed wood). All plant cells have primary cell walls made of cellulose, but the cells of woody plants have extra reinforcement from a secondary cell wall that contains lignin. Plants that survive just one or two growing seasons — that is, annuals or biennials — are typi- cally herbaceous plants. Plants that live year after year, called perennials, may become woody.
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