WOOD & HERBACEOUS STEM ANATOMY

WOOD: secondary xylem - water transport & strengthening tissue made up of specialized cells with thick inner walls
MORPHOLOGY
    Bark
      cork
      cortex
      endodermis
    Phloem
    2o Cambium
      phloem
      xylem
      (1o elongation: shoots, twig tips)
    Pith
    Rays

    2o Xylem (wood)
      Sections:
        Radial
        Tangential
        Cross-section
      Rings
        Early Wood
          less dense, lumina wider, walls thinner
        Late Wood
          dense, relatively thick walls
        Transition: abrupt, gradual



CONIFER WOOD "softwoods"

    Non-Porous: without vessels
    Water Transport by Tracheids
      resin canals (i.e. radial canals [also: axial, traumatic])
        e.g., Larix, Pinus, Picea, Pseudotsuga
      without resin canals
        e.g., Abies, Calocedrus, Sequoia
    Tracheids:
      Border Pits

      Spiral Thickenings
      Cracks
    Rays
      Fusiform (with resin canal)
      Uniseriate
      Parenchyma (heterogenous)
        upright, procumbent
      Ray Tracheids
        thickened walls, slanting ends, ± teeth
        ± Nodular Endwalls ( & parenchyma)
      Cross-Field Pitting: rays X parenchyma
        Cell Wall



ANGIOSPERM WOOD "Hardwoods"

    Porous: with vessels (trachea)
    Diffuse Porous
      vessels scattered throughout annual rings
      and/or uniform in size
      e.g., Tilia, Juglans, Betula
    Ring Porous
      vessels collected in one part of ring
      and/or larger in early wood
      e.g., Fraxinus, Quercus, Ulmus
    Vessel ends
      Open Fagus

      Sieve Plates Liriodendron scalariform
    Pits (between vessels)
      Scalariform Magnolia elongate, spiral
      Opposite Liriodendron round, rows
      Alternate Acer, Populus
    Rays (parenchyma)
      Uniseriate, multiseriate
      homogeneous
      heterogenous (upright, procumbent)
    Parenchyma
      Paratrachial (associated with vessels)
        Scanty Acer
        Vasicentric Morus
        Aliform Fraxinus
        Banded Confluent
        Boundary
        Terminal Populus
      Apotrachial (not surrounding vessels)
        diffuse e.g., Quercus
        banded e.g., Tilia
          Tyloses: outgrowth of parenchyma cell into vessel, forming partial or complete blockage of lumen



HERBACEOUS STEM

GENERAL ANATOMY
    Wood absent: Vascular bundles scattered in cortex of stem.
Tissue Systems
    Dermal
      Epidermis, Stomata, Cuticle, Collenchyma
    Fascicular, Vascular
      Vascular Bundles (see types below)
        Phloem, Cambium, Xylem
      Interfascicular Region
    Fundamental
      Cortex
      Pith: Starch, Sheath, Endodermis, Casparian Strips (occasional)
Arrangement of Vascular Bundles (herbaceous and 2o woody)
    Conifers and Angiosperms
      Vascular Ring between Cortex and Pith
    Monocotyledons
    • Two Vascular Rings: Avena, Hordeum, Secale, Triticum, Oryza
    • Scattered Vasc. Bundles: Bambusa, Saccharum, Sorgum, Zea
    • Also: outer ring embedded in sclerenchyma Layer
    Vines: wide rays (=interfascicular) with bands of perivascular fibers
Types of Vascular Bundles
  • Collateral Phloem (Phloem outside xylem): most common
  • Bicollateral Phloem (Phloem both sides): Apocynaceae, Asclepiadaceae, Convovulaceae, Cucurbitaceae, Solanaceae, some Compositae
  • Amphicribal Bundles (Phloem around Xylem): Ferns, some Angiosperms
  • Amphivasal Bundles (Xylem around Phloem): Rheum, Rumex, Mesembryanthemum, Begonia, Araceae, Liliaceae, Juncaceae, Cyperaceae
  • Alternating layers of Xylem and Phloem: Amaranthaceae, Chenopodiaceae, Menispermaceae, Nyctaginaceae



TYPES TO TELL APART
Abies
Juniperus
Pinus
Fraxinus
Quercus


Conifer Wood

    Cross Section

    Radial Section

    Tanjential Section


    Juniperus sp.


    Pinus flexilis


    Pinus ponderosa


    Abies lasiocarpa



    Angiosperm Wood

    Fraxinus
    Juglans
    Quercus
    Ulmus
    Tilia



    Herbaceous Stem

      Cucurbita
      Zea

    Acacia willardiana rachis vascular bundle

    Fouquieria vascular bundle

    Fouquieria sclerenchyma bundle

    References

    Links:

    Jefferson Patterson Park and Museum fresh & charcoal

    UofAz Wood Sections http://www.geo.arizona.edu/palynology/geos581/woodsectn.html

    Crow Canyon Karen Adams