树木年轮-木材解剖学课件

White Fir
Grand Fir
Wood Type 1: Conifer Wood
Wood Type 1: Conifer Wood
Wood TypeFra Baidu bibliotek1: Conifer Wood
Ring porous: large earlywood vessels
Ring porous: large earlywood vessels
Vessels
Fibers
Rays
Chestnut and Oak
Sassafras and Black Locust
Elm and Hackberry
Hickory and Pecan
Oaks rarely have missing rings but they can have very compressed growth.
Yellow Pines = thick latewood
Southern Pines
Ponderosa Pine
Red Pine
White Pines = thin latewood
Eastern White Pine
Western White Pine
Sugar Pine
Balsam Fir
… tree growth actually begins in the crown and moves downward due to the growth regulator, auxin.
Like “melting wax” !!
Meristems: apical and lateral growth D: cell division E: cell elongation M: cell maturation
Cell lumen Cell wall
Wood Types
Coniferous
Diffuse Porous
Ring Porous
Conifers: radial files of cells (for most species)
Note: colors are inverted! This is an x-ray!
Rays
Sugar Maple
Red Maple
Dogwood
Bark: dead, outer tissue that protects the cambium from the external environment and exposure to pathogens and physical injury.
Vessel: the composite, tube-like structure found in hardwoods from the fusion of cells in a longitudinal column. Fiber: an elongated cell with pointed ends and a thick or infrequently thin wall. Rays: ribbon-shaped tissue extending in a radial direction across the grain of the wood.
STEM ANALYSIS
Locally Absent Rings
Rings may be locally absent along the length of the tree.
False Ring Cells leading into the false ring will gradually decrease in size and then gradually increase back to earlywood cells.
Meristems: annual growth can also be seen in the branching patterns of many tree species (esp. conifers)
When we dissect the trunk, we can see this annual incremental growth, both upward and outward.
Oak often exhibits an offset in the rings across rays.
Diffuse porous: small vessels throughout
Diffuse porous: small vessels throughout
Vessels
Fibers
Conifers: radial files of cells (for most species)
Conifers: radial files of cells (for most species)
Tracheids Resin ducts
Horizontal rays
Conifers: radial files of cells (for most species)
Note the five major portions of the tree trunk.
Phloem (inner bark)
Cambium
Xylem (wood)
Role of heartwood is…?
Role of sapwood is…?
The Wood Cell: 1. Holocellulose a. alpha-cellulose (40-50%) = non-soluble = long-chain polymers (glucose) b. hemicellulose (20-35%) = readily soluble = short-chain polysaccharides 2. Lignin (15-35%) – non-carbohydrate materials in cell wall, very complex chemical structure. 3. Numerous Extractives – can be removed! a. tannins b. oils and resins c. other complex organic compounds
Viewing wood: tangential, radial, and transverse planes. We are only interested in which of these?
Definitions:
Cambium: the growing (generative) layer between the xylem and phloem. Xylem: principle strengthening and water conducting tissue of the stem, roots, and branches. Phloem: inner bark, principal function to distribute manufactured foodstuffs.
Wood Anatomy of Tree Rings
Tree growth begins with photosynthesis to produce new wood when the growing season begins.
Like “melting wax” !!
Trees grow upward and outward (including root tips), but…