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Botany of Trees California’s Part 2: How Wood Forms Iconic Flora North Coast California Na.ve Plant Society Free Webinar 7 PM Tomorrow Night Dr. Ma9 Ri9er h9ps://us04web.zoom.us/webinar/register/ WN_s4i_BmnlTryUe_7t45a9Qw Botany of Trees Tuesday, April 14th: IntroducTon to trees, growth, development, leaves, and morphology • Five part series -Tuesdays, 11 AM to 12:30 PM • Each will be ~1 hour with 30 minutes of ques.ons Tuesday, April 28th: Tree names, Tuesday, April 21st: Trunks, branches, diversity, and why names change tree form, branching pa9erns, and shape, and how wood forms Tuesday, May 5th: Water in trees, Tuesday, May 12th: ReproducTon, photosynthesis, and respiraTon flower formaTon, fruit, and seeds All aboveground plant structures are: Interpret the sharp structure: stems, leaves, or buds Modified leaf - spine bud becoming a new branch Pointy Structures on Plants Big Leaf Maple (Acer macrophyllum) Thorn Spine Prickle modified branch modified leaf epidermal that comes from that comes from outgrowths that an axillary bud below the occur at random on axillary bud the stem (not necessarily at nodes) Big Leaf Maple (Acer Pine Leaves macrophyllum) • Leaves of two kinds: primary scales and secondary needles • Primary leaves of pines are membranous scales • A set number of needle leaves are produced on short branches (fascicles) • Each bundle (fascicle) of needles is surrounded by membranous bud scales Leaf Leaf Leaf Stump SprouTng & Epicormic Growth Meristems: where growth occurs • Apical Meristems • Form primary .ssues • Increase in plant length and height Trees get taller because of primary growth Leaf A9achment (Phyllotaxy) DisTchous Decussate Shoot Apical Meristem Alternate Opposite Whorled Leaf Form (Shape) pinnate leaf venation terminal leafet leaf blade leafet leaf veins leaf axil leafet stipules petiole secondary axillary leafet petiole bud nodes rachis primary stem leafet Simple Pinnately Bipinnately Palmately Compound Compound Compound Secondary Growth in Trees • Why wood and bark are needed • Vascular cambium • Ini.a.on, fusiform ini.als, rays, cambial cells, grows and development of the cambium • Secondary Xylem • Types of cells in wood, growth rings, heart wood / sap wood / reac.on wood • Secondary Phloem and Bark • Cork and cork cambium, len.cels Root - Leaf Constraint Meristems: where growth occurs • Lateral meristems young young old • Form secondary .ssues Monocot with a stem Broad-leaved tree with a vascular cambium • Increase in plant girth Palm Trees • Vascular cambium Grass • Cork cambium old Monocot without Tree increase in girth a stem because of secondary growth Vascular Cambium Phloem Cork Xylem 3 1 2 Pith Cork Vascular Rays Phloem Vascular Cambium Rays (darkly stained 3 cells) Xylem 2 1 Growth rings result from “And see this ring right here, Jimmy? … That’s different cell sizes in another Tme when the old fellow miraculously xylem Tssue survived some big forest fire.” Heartwood no longer conducts water, sapwood sTll does. Heartwood Sapwood Sequoiadendron 200 years Quarter-sawn Wood White Oak Cuts Cross-secTon (x) TangenTal Radial (T) ® Cell Types in Wood • Conduc.ng cells • Tracheids • Vessel elements • Fibers - structural • Parenchyma - living thin-walled cels The density of different Rosewood A Balsa woods is based on the cells that make up that wood B Weaker Wood Strong Wood The characterisTcs of different woods is based on its evoluTonary history Hard Wood Soft Wood • Gymnosperms (conifers or soUwood trees) - Only tracheids • Angiosperms - (flowering or hardwood trees) Vessel Elements + Tracheids • Both have fibers, but they Douglas Fir are more common and Red Maple (Acer rubrum) abundant in angiosperms (Pseudotsuga menziesii) branch ReacTon Wood load Graning • Gymnosperms (conifers) - • Most economically important type compression wood of plant propaga.on aUer seeds • Angiosperms - tension wood • Transplan.ng a shoot from one plant to another • Scion- bud or shoot • Stock- root stock Cork Cambia LenTcels Cork Oak (Quercus suber) LenTcel Stem cross secTon Bark Secondary Phloem Wood Summary Botany of Trees • The leaf - root constraint is solved by making www.wcisa.net more conduc.ng cells. to register for the next session • The forma.on of wood is due to the ac.vity of Introduc.on to trees, growth, development, leaves, and April 14th the vascular cambium morphology. Trunks, branches, tree form, branching pa_erns, and shape, and • Growth rings vary and they’re due to differen.al April 21st how wood forms growth of the vascular cambium • The character of different woods is based on the April 28th Tree names, diversity, and why names change different cells in it May 5th Water in trees, photosynthesis, and respiraTon • Cork cambia form as living cells that give rise to dead protec.ve cells on the outside of the bark May 12th ReproducTon, flower formaTon, fruit, and seeds Botany of Trees CEU and Survey Link: h9ps://www.surveymonkey.com/r/ ri9erpart2.
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