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PLANT STRUCTURE & GROWTH Nancy G. Morris Volunteer State Community College Campbell, 5th edition, Chapter 35 Plant Tissues • I. Meristematic Tissue • II. Dermal, Surface, or Protective • III. Ground or Fundamental I. Meristematic Tissue • A. Apical Meristems • Primary growing tips of shoots & stems • B. Lateral Meristems • Produces lateral growth; increase in girth • 1. Vascular Cambium • • Between primary xylem & phloem 2. Cork Cambium • Between bark and phloem II. Dermal, Surface, or Protective • A. Roots – – • root hairs for adsorption no waxy covering B. Stems – • cork, cork cambium C. Leaves – – – – trichomes (multicellular leaf hairs) waxy cuticle on epidermis stoma on lower dermis Special xerophytic adaptations III. Ground or Fundamental • A. Parenchyma • 1. Storage Parenchyma • 2. Chloroenchyma • B. Collenchyma • C. Sclerenchyma • • 1. Fibers 2. Sclerids • D. Vascular Tissues • 1. Xylem • • • a. tracheids b. xylem vessels 2. Phloem III. Ground or Fundamental • A. Paraenchyma – Figure 35.11 • • • • • • unspecialized living primary cell wall thin & flexible capable of dividing metabolic synthesis storage of starch in plastids • Chlorenchyma – specialized parenchyma • photosynthetic Paramechyma III. Ground or Fundamental • B. Collenchyma – • • • • primary cell walls thickened at corners grouped in strands or cylinders to support living cells which elongate as plant grows Figure 35.11 Collenchyma III. Ground or Fundamental • C. Sclerenchyma – Figure 35.11 • • • • • • • dead cells rigid, thick secondary cell walls of lignin support for non-growing parts of the plant fibers – long, slender, tapered cells in bundles sclereids – (pears: stone cells) shorter, irregularly shaped cells Fiber cells (Bundle cap) Sclerids or Stone Cells III. Ground or Fundamental • D. Vascular Tissues • 1. Xylem: water-conducting cells secondary cell walls laid down in spiral/ ring patterns (which allow stretching) growing parts • a. Tracheids – long, thin, tapered cells with lignin walls and bordered pits » Water flows from cell to cell through pits » Also function in support • b. Xylem vessel – wider, shorter, thinnerwalled, less tapered (Figure 35.9) » Aligned end to end to make an element » Hollow tubes Xylem • • • • conducts water tracheids evolved first found in soft woods (balsam, pine) hard woods have both tracheids & xylem vessels • thick walls • dead at maturity Pressure flow in a sieve tube Roles of cohesion & adhesion in the ascent of xylem sap III. Ground or Fundamental • D. Vascular Tissues – Figure 35.9 • 1. Phloem – food-conducting cells • • • • • • • living thin-watery cytoplasm sieve-tube members transport sucrose sieve plate -perforated end wall callose slime plugs prevent leakage companion cells provide nuclear control Phloem • • • • alive at maturity non-nucleated nuclear control by Companion Cells sieve-tube members are the sugartransporting cells • possess sieve plates between adjacent cells • slime plugs of callose prevent leaking when damaged 35.9 Food-conducting cells of the phloem Vessel Elements Anatomy of an Angiosperm The Angiosperm Body Roots & shoots are adaptations to living on land! • Roots functions: – 1) anchor the plant on land – 2) absorb & conduct water & minerals – 3) store food (tap root) • Root types: – 1) tap root – carrots, turnips, sweet potatoes – 2) fibrous root – primarily in monocots • Root features: – 1) root hairs – increase surface area – 2) mycorrhizae – symbiotic root fungus – 3) adventitious roots – above ground –prop roots Root Structure (Figure 35.14 ) Root tip Roots hairs Lateral Root Dicot Root Monocot and Dicot Root Comparison Casparian Strip Shoot System: vegetative & floral shoots • Stem morphology: – – – – 1) nodes – where leaves are attached to stems 2) internodes – space between leaves 3) axillary buds – bud in leaf axil 4) terminal buds – bud on shoot tip • Stem modifications: – 1) stolons (strawberry runners) – 2) rhizomes (horizontal underground stems, irises) – 3) bulbs (vertical, underground shoots with leaf bases modified for food storage,onions) – 4) tubers (potatoes- swollen ends of rhizomes) – Figure 35.6 Iris rhizomes Figure 35.4 Stem Morphology Stem Anatomy Stem Anatomy Production of Secondary Vascular Tissue Anatomy of stem: Secondary Growth All wrapped up! Shoot System: vegetative & floral shoots • Leaf functions: • Absorption of light energy for photosynthesis – – – – – Other modifications: 1) support 2) protection 3) storage 4) attract pollinators • Leaf modifications: (Figure 35.8) – – – – 1) tendrils – cling for support 2) spines – protection 3) succulents – storage of water 4) color – attraction of pollinators Figure 35.20 Anatomy of a Leaf Cross section of a mesophytic leaf Gas Exchange through the stoma: Transpiration Simple vs. Compound Comparison of Monocots & Dicots Uptake of nutrients Angiosperms produce •Flowers •Fruits •Seeds Anatomy of a Flower Anatomy of a Seed Germination: Hypogean & Epigean Plasmodesmata