PLSC Lab Three

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  1. Bark or Cork
    Is waterproof and used to make containers, shelters, vessels (canoes) decorative items and fuel
  2. Wood, practical use
    Inner part of the tree, has amazing physical properties that allow us to make fuel, paper, furniture, dwelling, bridges, tools, and multiple other things.  Each tree species has unique properties that suit them better for one wood product over another.
  3. Secondary growth
    Woody tissues are this, and arise from lateral meristems
  4. Lateral meristem
    Creates woody tissues.  They cause increases girth of a shoot or root.
  5. Trees
    Most are large, woody, single-stemmed plants. The body of the tree can be divided into a lower trunk that branches above into a leafy crown.
  6. Coppiced
    A clumped arrangement of stems common in birch, but is usually associated with shorter shrubs
  7. Flaring buttresses
    Produced by older specimens of trees like western red cedar (Betula) at the base of the trunk to help provide support
  8. Saplings
    young individuals of tress that are less than 5 to 10 m
  9. Root suckers
    are new shoos that arise from the roots of an existing tress, and as such the two trees are genetically identical clones.   Technically the original tree is the ortet, and each new sucker a ramet, and  all members of a clones are genets.  Suckering is a very common means of asexual reproduction among woody dicots in western Canada
  10. Layering
    The conifer method of asexual reproduction, when snow-laden branches contact the ground and become entangled in moist forest floor litter, after which adventitious roots develop from the point of contact between the branch and soil giving arise to a new sapling. Common among black spruse
  11. Twigs
    woody branches. Can be used to age a specimen accurately.  In the case of dicots, a terminal bud scale scar on each young twig indicates the past position of a terminal bud.  The distance between the terminal bud and the closest bud scale scar is the current year's longitudinal growth.
  12. Conifer branch development
    A single whorl of lateral branches indicates the past position of the terminal branch, or leader.  The distance between the uppermost whorl to the tip of the leader is the current year's longitudinal growth.  The growth of several years can be identified and measured by the location of lateral branch whorls
  13. Wood (generically)
    Is the generic term for accumulated xylem tissue at the core of a woody shoot or root.
  14. Rays
    pith parenchyma between bundles are compressed into rays of soft living tissue within lignified and dead xylem.  With age, the rays become discontinuous and scattered throughout the width and length of the shoot.
  15. Phloem
    also accumulates, but the thin cellulose laden walls break down with time and the resulting phloem layer remains relatively thin.
  16. Vascular cambium
    One the rays have become compressed and individual bundles are no longer visible, the whole cambium is called a vascular cambium
  17. Phellogen
    A second lateral meristem develops within the cortex of woody stems to form the phellum or cork to the outside and the phelloderm inward toward the phloem.  Layers of dead phellum can be seen under the epidermis. The phellum contains cells with suberized cell walls that repel water and prevent gas exchange. These three tissues are called the periderm and make up the bark of the tree
  18. Lenticels
    The outer surface of periderm on younger twigs also has openings of spongy phellum called lenticels, which allow for gas exchange between the phellogen and vascular cambium. Some smooth barked trees such as the paper birch have visible lenticels on the bark.
  19. Tree rings
    indicate changes in the cambial activity and growth rate over the course of a year.  In spring, rapid cell divisions produce large diameter, thinner walled xylem called early wood or spring wood.  In summer and fall, cell division slows and produces narrow diameter, thicker-walled xylem called late wood or summer wood.
  20. Ring-porous species
    the early wood xylem cells are distinctly larger than those of late wood, and tree rings are quite distinct.  (conifers)
  21. Diffuse porous species
    the pores are fairly uniform or gradually change through the growing season.  Woody dicots are notoriously difficult to age because of this diffuse-porous anatomy
  22. Resin ducts or resin canals
    The most obvious difference between gymnosperms and dicots, which the gymnosperms have. Large resin ducts are present in the cortex of young conifers stems and smaller resin ducts are visible throughout the xylem of all conifers.  Ducts are surrounded by living parenchyma cells that secrete resin into the ducts, and this resin accounts for the stickiness and fragrance of freshly cut conifer stem
  23. Bordered pits
    Tracheids permit passage of water through these, or gaps in the lignified secondary cell walls between tracheids. Both tracheids and fibers can be found in the wood of dicots but the more advanced vessel elements are only present in dicot wood.
  24. Difference in gymnosperms and dicot phleom
    In gymnosperms, sugars are transported through sieve cells fueled by adjacent albuminous cells while the more advanced phloem sieve tube elements and companion cells found in angiosperms
  25. Roots
    also form woody tissues
  26. Heartwood
    When older xylem, tracheids, and/or vessel elements break down and supporting parenchyma ray cells distintegrate.  The central core is called heartwood and may become darker in color than the younger wood.  In particular, some may rot away completely and leave a hollow core.  The outermost layer that is stilling functioning is called sapwood.
  27. Wood quality
    Grade, based on toughness of wood (hardwood, woody dicots and softwood, conifers); the grain; defects, knots, fire scars; warps
  28. Negative geotropism
    Many shoots grow upward, against the pull of gravity
  29. Positive phototropism
    Leaves and younger shoots or hardwoods are drawn by sunlight
  30. Reaction wood
    When a shoot bends in attempt to acquire light.
  31. Dendroecology
    Study of trees rings to reconstruct past environments
  32. Compression wood
    in softwoods, the wood formed on the side of a bent tree
  33. Tension wood
    in hardwoods, the wider rings on the upper side of the bend...
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PLSC Lab Three
2013-04-01 14:26:34
Lab Three

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