Botany Unit 2 Wood and Bark

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Terms in this set (27)
angiosperm woodflowering plant trees and shrubs complex axial system vessel elements tracheids fibers axial parenchymagrowth ringsform in trees of temperate regions due to water availibilityearly (spring) woodwater abundant vessels numerous and wide in diameterlate (summer) woodwater less abundant vessels less numerous and narrow in diametersapwoodfunctional xylem that is actively conducting water problem non-conducting xylem serves as a route for fungal and bacterial diseasesheartwoodnon-functional wood that has ceased conducting need to be sealed off to prevent infections tyloses gummosis may store waste products these changes cause the wood to change colortylosesparenchyma cells next to a vessel element grows through pits backs up the old vessel elementgummosisparenchyma next to vessel element secrete gummy substances into the vesselbarksecondary phloem and periderm replaces epidermis takes over functions of epidermis protection gas exchangeouter barkperiderm dead tissuesinner barkphloem living tissueperidermsecondary tissue that replaces the cortex and epidermis multiple layers of periderm each layer formed by a phellogen layer only innermost layer is livingphellogenmeristematic layer derivatives produce phellem layers (cork cambium)phellemdead and suberized (cork cells)lenticelarea of bark surface with loosely packed spongy cells large intercellular spaceslenticel functionallow gas to enter the outer bark circulate to inner barkphellodermtissue formed inwardly by the cork cambium inner part of the periderm