Chapter 43 Plant Anatomy Nutrient Transport Flowering plants 2 main groups Monocots One cotyledon Embryos Veins usually parallel Leaf venation Vascular bundles usually complexity arranged Stems Fibrous root system Roots Floral parts usually in multiples of three Flowers Eudicots Dicots Two cotyledons Embryos Veins usually netlike Leaf venation Vascular bundles usually arranged in ring Stems Taproot usually present and has one main root with several branches Roots Floral parts usually in multiples of 4 or 5 Flowers Monocot e g corn seedlings each have 1 cotyledon seed leaf in monocots the cotyledon often remains within the confines of the seed Dicot e g bean seedlings each have 2 cotyledons seed leaves Organ systems of flowering plants 1 Root system Primary root first to appear Eudicot Taproot Monocot Fibrous root system Lateral roots Root hairs are extensions of epidermal cells Root hairs dramatically increase a root s surface area for absorbing water and nutrients Food storage is a function of all roots but some e g carrot taproots are highly modified for storage Aboveground aerial or prop roots give extra support Breathing roots conduct oxygen to waterlogged roots Epiphyte plant that lives on another plant the roots of many orchids are photosynthetic Ex Spanish moss not actually moss produce flowers 2 Shoot System STEMS support branches flowers which become fruits leaves etc Some plants have specialized water storage stems Baobab trees Saguaro cacti Stolons runners are horizontal wandering aboveground stems asexual reproduction Rhizomes e g edible base of a ginger plant are horizontal belowground stems Tubers e g potatoes yams are the swollen ends of rhizomes specialized for food storage fiber content can be different NOT ROOTS Bulbs are vertical underground stems consisting mostly of the swollen bases of leaves specialized to store food layers of an onion that you peel off are modified leaves Tendrils are specialized branches that twist around structures to lend support Thigmotropism a movement in which a plant moves grows in response to touch Thorns are rigid sharp branches that deter potential herbivores especially mammalian browsers natural selection LEAVES Some arid adapted plants have succulent leaves Ex Aloe Vera Leaves specialized into spines help defend against herbivores Advantages of being a carnivorous plant vs a non carnivorous plant more energy more soil nutrients from the roots Digest prey THEN absorb them Venus fly trap 2 trigger hairs must be touched in succession within 20 seconds of each other or one hair touched twice in rapid succession they can count doesn t close in rain or wind Leaves specialized to trap animals occur in carnivorous plants Pitcher plants Leaf hairs trichomes help reduce water loss and provide some protection against herbivores creates a barrier which helps stop the flow of air keeps away small animals from getting on leaf BUDS Meri stem cells have the ability to become any cell type in a plant these stem cells are stored all around the plant Undifferentiated meristematic cells occur in buds Terminal bud shoot apex Apical means at the end or tip apicals of the stem What occurs to make plant longer goes through plant cycle leaves behind a bunch of baby plant cells Axillary bud at the base of every single leaf dormant meri stem cells Terminal bud of branch Whole plant growth is indeterminate do not grow to certain size then stop Leaf and flower determinate growth pattern When a cell divides the daughter cells grow and they may differentiate specialize depending especially on where they re located during development Every single cell in a plant human comes from preexisting cells Differentiated cells contribute to 3 tissue systems 1 Dermal tissue epidermis Generally a single cell layer that covers the plant Absorption in root system Water retention in shoot system aided by waxy cuticle helps prevent water loss cannot easily leave this waxy layer 2 Vascular tissue center pipes of plant Xylem transports water and dissolved minerals Vessel element Tracheids moves water using tubes Phloem transports sugars dissolved in water cells never die unless plant dies Sieve tubes element sieve plates companion cell 3 Ground tissue All non epidermal non vascular tissue 3 principal cell types Parenchyma Thin walled live cells Perform most metabolic functions of plant Photosynthesis food storage synthesis and secretion Collenchyma Cells with unevenly thickened walls allows these structures to flex Alive at maturity Aid support without constricting growth Sclerenchyma Very thick walls hardened with lignin Dead at maturity Give strength and support Hardness to nutshells and the gritty texture to pears Primary growth in roots Primary growth in roots lengthens roots from the tips The root cap continually sloughs off protects the apical meristem zone of cell division Lots of mitosis going on The apical meristem produces three primary meristems Protoderm cells become the epidermis Ground meristem cells become the cortex Procambium cells become the vascular cylinder stele of the root The cells first elongate zone of elongation then mature and differentiate zone of maturation Controlled by plant hormones Pericycle Outermost layer of stele These cells retain meristematic capabilities and can produce lateral roots Endodermis Innermost layer of cortex These cells regulate the flow of substances into the vascular tissues of the stele Casparian strip Disallows flow of substances except through the endodermal cells themselves Shoot primary growth lengthening shoots from the tips Apical meristem produces the same3 primary meristem as in the roots More complex due to organs leaf flower Protoderm ground meristem procambium Meristems left behind form leaves on each side of the apical meristem pushed out to side cells that flank Leaf primordia cells that flank from the apical meristem Some meristem cells form leaf hairs Axillary buds that could produce lateral branches develop from islands of meristematic cells left at the bases of leaf primordia Lateral branches are similar to lateral roots formed from pericycle cells Procambium cells develop into vascular bundles Formed around circumference of the stem in dicots Monocots vascular bundles are scatted to form spacing between them that are controlled In a leaf they are veins or pipes in the leaf used for communication Half dead half alive xylem phloem in capillaries bring oxygen nutrients to different parts humans of the body
View Full Document
Unlocking...