Biology - Jones Illinois Arborist Association

Page 1 Tree Biology Grant Jones grant.jones@davey.com 630.797.8581 Page 2 Tree Biology In order to grow trees, we need to understand how trees grow Image from Internet Page 3 Two Trees Image from The Body Language of Trees Page 4 • 5% Leaves • 15% Stems • 60% Trunk • 15% Woody Roots • 5% Absorbing Roots Ratio of Whole Tree Structures Image from Internet Page 5 Tree Biology • Anatomy (cellular structures) • Morphology (organs) • Physiology (chemical/biochemical) Page 6 Plant Cell (ISA Diagram) Page 7 • Cellulose – (a complex sugar) Cell Wall Image from Internet Page 8 How does a tree go from 1 cell to a 300 foot redwood? Growth Images from Internet Page 9 • Not all cells are identical. • Specialization of each individual cell occurs after cell division, this is call differentiation. • A cell may become the bark, flower, wood, root, etc. Differentiation Page 10 • Apical/Primary Meristem – meristem located at tips of shoot and roots • Lateral/Secondary Meristem – residual meristem responsible for secondary growth and ultimate size trees obtain. – Vascular Cambium – produces xylem (sapwood & heartwood) & phloem – Cork Cambium – produces bark Meristem Types Page 11 Apical Meristem Image from Internet Page 12 Image from Physiology of Woody Plants by Kozlowski and Pallardy Growth – Lateral Meristem Page 13 Factors Affecting Growth Image from Internet Page 14 • Moisture • Air • Nutrients • Temperature • Light Environmental Factors Page 15 Image from ISA Growth Cycle Page 16 • Support for the tree • Store carbohydrates • Movement of water and nutrients Trunks, Stems, and Branches Page 17 Image from ISA Stem Structure (young stem) Page 18 Thin layer of cells that produce xylem to the interior and phloem to the exterior. Vascular Cambium Page 19 Phloem – Sieve Tube Cells Image from Internet Page 20 Cork Cambium Initiation Cork Cambium & Cork Cork Cambium Images from Internet Page 21 • Tracheids – elongated dead cells with pointed ends and thick walls containing pits • Vessels – Stacks of dead, hollow cells that form long tubes stacked above each other • Fibers – Provide mechanical strength Xylem Structures Page 22 Images from Plant Physiology by Taiz and Zeiger Vessels (Angiosperm Wood) Page 23 Image (left) from Plant Physiology by Taiz and Zeiger Tracheids (Conifers) Page 24 • Softwood – wood composed of only tracheids (pines, other conifers & gymnosperms). • Hardwood – wood composed of tracheids & vessels (angiosperms) Wood Types Images from Internet Page 25 Image from ISA Mature Stem Page 26 • Sapwood- living wood that conducts water. – Conifers often have 8-12 living rings. – Angiosperms (e.g. elms, oaks) often have 1-2 living rings, while maples may have 4-6 living rings. • Heartwood- dead xylem that does not conduct water. Sometimes darker in color than sapwood. Will form boundaries when wounded. Xylem (Wood) Page 27 • Transport from roots to shoots • Stored energy • Mechanical support cells with strong walls of cellulose and lignin • Produce chemicals to resist decay Functions of Sapwood Page 28 – Ring Porous- large vessel produced in spring and smaller vessels in summer. – Diffuse Porous – vessel roughly the same size in spring and summer. Wood Types - Hardwoods Page 29 • Few annual rings (1-2) • Springwood/Latewood Hardwood Ring Porous (Oak) Images from Internet Page 30 • Tree-of-Heaven • Hickory • Chestnut • Hackberry • Ash* • Honeylocust • Coffetree • Osage-Orange • Mulberry • Red/White Oak Groups • Black Locust • Elm Ring Porous Page 31 • Sapwood is many annual rings (4+) Hardwood Diffuse Porous (Maple) Image from Internet Page 32 • Maple • Buckeye • Alder • Birch • Hornbeam • Dogwood • Hazelnut/Filbert • Beech • Holly • Sweetgum • Cherry (Prunus) • Yellow-Poplar (Tulip Tree) • Magnolia • Black Gum/Tupelo • Hophornbeam • Sourwood • Sycamore • Poplar/Aspen/Cottonwood • Buckthorn • Willow • Linden/Basswood Diffuse Porous Page 33 Formation of larger conducting cells in spring and then smaller cells in the summer and no (or little) growth in winter create rings. Growth Rings Page 34 • Thin lines of cell that extend from the phloem toward the pith. • Rays transport water, sugar, and other compounds. Rays Image from Internet Page 35 Lenticels • Small openings in the bark that allow for gas exchange Page 36 Lenticel (microscopic) Image from Internet Page 37 • Living cells linked together by plasmodesmata • Radial and axial transport of nutrients, carbohydrates, water and other solutes • Solutes can move in the symplast, but cells usually take up compounds they need and export those available in excess. Symplast Image from Internet Page 38 • Apoplast consists of the vessels, fibers, cell walls and open spaces of the sapwood • Water and solutes can move freely in the apoplast (transpirational pull) Apoplast Image from Internet Page 39 Branch Attachment Image from ISA Page 40 Image from Up by the Roots Branch Anatomy Page 41 Twig Morphology Page 42 Image from ISA Internode & Node Page 43 • Photosynthesis – Sugar production • Transpiration – Water regulation and gas exchange Function of Leaves Page 44 Leaf Structure Image from ISA Page 45 • Nitrogen, magnesium, iron, and sulfur make up the chloroplasts and chlorophyll Chloroplasts Image from Internet Page 46 Leaf Showing Cuticle (red) Image from Internet Page 47 • Deciduous- trees that lose their leaves in Fall • Petiole – stalk that attaches leaf to stem • Evergreen – trees that hold their leaves for more than 1 year Page 48 Fall Color • Cool Days (not freezing) • Shorter Days • Bright Sunny Days • These three factors increase sugar accumulation, which decreases chlorophyll production and allows other pigments to become visible (anthocyanins & carotenoids). Page 49 • Cellular changes that allow leaf drop • Protects region on stem from desiccation, insect invasion, and disease infection. Abscission Zone Page 50 Abscission Zone Images from Internet Page 51 Needle Drop Page 52 Roots • Anchor & Support • Absorb Water & Nutrients • Store Water & Energy Rich Compound and Conduct Them to the Trunk • Produce Organic Compounds Page 53 • Available Water • Proper Drainage (no flooded soils) • Available Oxygen (no compaction) • Available Nutrients • Soils roots can penetrate • Avoid Mechanical Injury Healthy Roots = Healthy Plants Image from Internet Page 54 Image from The Influence of Soils and Species on Tree Root Depth by Peter Crow What Does a Root System Look Like? Page 55 Image from ISA Roots Page 56 Root Crown Page 57 Image from Up from the Roots Root Types Page 58 • Absorbing Roots – fine non-woody roots responsible for water & nutrient absorption typically in top 1-foot of soil Root Types Page 59 Root Tip Anatomy Image from Internet Page 60 • Lateral Roots – Woody horizontal roots important for supporting the tree. Typically in upper soil surface. Root Types Page 61 • Sinker Roots – Woody vertically downward growing roots helping to anchor tree and exploit soil depth. Root Types Page 62 • True Tap (Hickory, Pine, Walnut, Coffeetree • Heart Roots (Red Oak) • Plate Roots (Maples, Most Trees, etc) Image from Principles and Practice of Planting Trees and Shrubs by Watson and Himelick Root Systems Page 63 Tap Root Page 64 Initial root developed during seedling growth. This root is typically choked out or diverted. Mature trees lack tap roots. Tap Root Page 65 Heart Root Images from Internet Page 66 Plate Roots Image (top left) from Internet. Images (bottom right and left) from Len Burkhart, PhD. Page 67 1. Symbiotic (beneficial) relationship between fungus and roots of a plant. 2. Benefits: 1. Absorption of water & nutrients 2. Physical protection-barrier to pathogenic fungi 3. Secret fungistatic substances that inhibit pathogenic fungi Mycorrhizae “fungus root” Page 68 Ectomycorrhizae Endomycorrhizae Image from Plant Physiology by Taiz and Zeiger Types of Mycorrhizae Page 69 Image from ISA Products From Photosynthesis Page 70 Sugar + Oxygen ↓ Energy + Carbon Dioxide + Water Respiration Page 71 The process where sugars are broken down in the presence of oxygen to release carbon dioxide, water, & energy. Respiration Page 72 • Trees under anaerobic conditions (lacking oxygen) cannot respire. • Living root tissue lacking oxygen (flooded soils, compacted soils) have limited respiration and can die as a result (essentially suffocation). All Living Cells Respire Page 73 Respiration Images from Internet Page 74 Image from the University of Minnesota All Living Cells Respire Page 75 • Loss of water through the foliage in the form of water vapor Transpiration Image from Internet Page 76 • Water vapor leaves the leaf through openings called stomata • Guard cells regulate the amount of water vapor that can exit the leaf Transpiration Image from ISA Page 77 • 90% through open stomata • Stomata open during day & closed at night • Transpiration cools leaf surface • Transpiration increases when: – Temps are high – Humidity is low – Wind speed increases – Adequate soil moisture Transpiration Image from ISA Page 78 What has more (salt), gets more (water)! Osmosis Image from Internet Page 79 • Axial Transport – Movement of water, nutrients, sugars and other solutes up and down in the tree • Radial Transport – movement of sugars across the xylem and phloem through rays Image from Modern Arboriculture Transport Page 80 • Leaves pump sugars into the phloem (sieve tubes) • Sugars are squeezed through the phloem which requires energy • Most energy stays nearby Image from Modern Arboriculture Phloem Loading Page 81 • Source – Plant structures that produce energy • Sink – Plant structures that consumer energy Source/Sink Page 82 • Heavy seed production can be a large sink and consume a lot of energy • Heavy seed production can be a sign of stress in landscape trees Sinks - Stress Page 83 • Inhibition of the growth of lateral buds (under hormonal control) • Removal of terminal bud can release lateral buds leading to new shoot development Image from ISA Apical Dominance Page 84 Single Stem-Excurrent Page 85 Decurrent Multi-Stemmed - Decurrent Page 86 • Suckers emerge below the graft union or from the root system. Shoot produced from stems or roots where meristems are not normally found. • Watersprouts form above the graft union and are typically produced from meristematic points that are carried along in the cambium (residual lateral bud). These are sometime called latent buds. Epicormic Shoots Page 87 Watersprouts Page 88 Latent Bud Page 89 Suckers (rarely adventitious) Page 90 • Auxin – root initiation, cell division, apical dominance • Cytokinin – cell division • Gibberellin – cell elongation • Abscissic Acid – leaf abscission • Ethylene (gas) – fruit ripening Plant Hormones Page 91 • IAA – Indole Acetic Acid (naturally occuring in the plant. • Synthetic Auxins – IBA, NAA, 2,4-D : used as rooting compounds and herbicides. Auxin Page 92 Orientation of growth in response to an external stimuli (auxins involved in this mechanism). Geotropism – response of plant to gravity (reason shoots grow upward and roots grow downward). Phototropism – plant growth towards light Tropism Page 93 Image from Up by the Roots Geotropism / Gravitropism Page 94 Phototropism Image from Internet Page 95 • Compartmentalization • Of • Decay • In • Trees Wall 1- resists vertical spread Wall 2- resists inward spread Wall 3- resists lateral spread Wall 4- resists spread to newly forming wood (diagram from Shigo, 1986) CODIT Page 96 Aerial Roots Page 97 • 1 bud (apical meristem) producing new leaves • If bud is killed the palm dies • Fronds produced slowly (1 month per leaf) • Damage to leaves while in the bud may take 1 year to visibly appear Palm Crown and Fronds Page 98 Palm Trunk • Can’t compartmentalize decay • Trunk won’t increase in width over time • Chronic environmental stress can cause “pencilling” of the trunk Page 99 • Cabbage Palms regenerate from root initiation zone (RIZ) • Coconut Palms will regenerate from root tip or RIZ • Queen and Royal Palms regenerate more new root tips Image (top) from Principles and Practice of Planting Trees and Shrubs by Watson and Himelick Palm Roots Page 100 Palm Trunks Image from A.D. Ali Page 101 Palm Trunks Images (left and top right) from the Internet. Image (bottom right) from A.D. Ali Page 102 Inflorescence Page 103 Grant Jones grant.jones@davey.com 630.797.8581