Tree Biology
Urban Forestry Commission Vincent Verweij July 25, 2019 What is a tree?
How is a tree different from a perennial herbaceous plant?
How is a tree different from a vine?
How is a tree different from a shrub? Trees perform Amazing feats of Physics
Pumping water up several hundreds of feet
Intercepting and evaporating thousands of gallons of water
Resisting extreme forces of wind energy, compensating with roots, flexibility, and changing wind dynamics BASIC BIOLOGY OF TREES Basic Plant Cell
Cell Walls- made of cellulose and lignin
Central Vacuoles- stores water and gives rigidity
Plasmoderma- connects cytoplasm
Chloroplasts- conducts photosynthesis Plant Cell Wall
Middle Lamella – shared with other cells, lignin and pectin, gives compressive strength
Primary cell wall – oriented cellulose fiber, gives tensile strength
Plasma membrane – same as animal cell membrane
When fungi attack these fibers, the trees weakens in different ways Wood Cells How does a tree grow?
Primary Meristem Secondary Meristem
AKA Buds AKA Cambium Elongates into shoots Located between bark and Produces wood Cortex Produces vascular tissue Epidermis Xylem persists as wood Lateral buds and moves water and Or becomes a leaf nutrients Or becomes a flower Phloem becomes bark or is reabsorbed and moves sugars Pericycle: a thin layer of structural plant tissue between the endodermis and the phloem. Endodermis: Layer between hard bark/root skin, allowing transfer of nutrients Tree Cross Section
Cambium: a cellular plant tissue from which phloem, xylem, or cork grows by division, resulting (in woody plants) in secondary thickening. A Closer Look
Vessels
Growth Ring
Early Wood/ Late Wood Divide Aging and Death
Must grow new sapwood every year. Why? This becomes a bigger and bigger energy drain. Can grow less wood, but that means less water for energy production. Eventually growth in energy demand is greater than growth in energy production, the tree goes into energy deficit, declines and dies. Some trees can decline for centuries WHAT DO TREES NEED? Water Water for establishment (natural and planted) More water as the tree grows Trees can store water, and have mechanisms to reduce evaporation in high heat A mature tree can evaporate several hundreds of gallons of water a day Soil
Nutrients Nitrogen, phosphorus, and potassium Metals (Iron, Zinc, boron, copper) Acidity Most trees around here prefer low, acidic pH Quantity and Porosity Trees need space to let their roots grow Compaction limits growth Soil Carbon dioxide and oxygen THREATS TO TREES Topping Poor landscape practice Decay Insect Pests Non-native Invasive Vines Root compaction and damage Extreme weather Storms
Drought ADAPTATIONS OF TREES Light needs
Tall Use of light spectrum Some understory trees and shrubs use part of the visible spectrum that canopy trees do not Sensitivity Pioneer trees need full sunlight, Tuliptree, for example Understory and ‘climax’ trees can tolerate shade Water/ Low oxygen Fire resistance - Bark Wind adaptation Deciduous leaves
More energy efficient Replenish degraded chlorophyll Even happens in tropical areas, in dryer seasons Different trees retain different chemicals after chlorophyll leaves, creating different colors Root anatomy Compartmentalization of Decay in Trees (CODIT) Compartmentalization of Decay in Trees (CODIT) Compartmentalization of Decay in Trees (CODIT) Resources
Trees: Their Natural History, by Peter A. Thomas Tree Mechanics Explained, by Claus Mattheck Trees for Urban and Suburban Landscapes, by Ed Gilman Urban Forests, by Jill Jonnes Up By Roots, by James Urban Youtube channel Veritasium, search “trees” Questions?
Vincent Verweij Arlington County Urban Forest Manager 703-228-1863 [email protected] Facebook.com/ArlingtonUrbanForestry TAXONOMY Taxonomy
Kingdom KD(P)COFGS – Division (Phylum) Lumps living things that are similar Class KD(P)COFGS – Order splits living things that Family are dissimilar Genus Genus species makes up Species scientific name What is a Tree?
A Rose is a woody shrub in the genus Rosa.
But the lowest taxonomic group which contains all trees is the Kingdom Plantae Evolution of Trees
Pine Oak Palm Kingdom Plantae – Plants Subkingdom Tracheobionta – Vascular plants Superdivision Spermatophyta – Seed plants Division Coniferophyta– Magnoliophyta– Flowering plants Conifers
Class Pinopsida Magnoliopsida– Liliopsida– Dicotyledons Monocotyledons Convergent Evolution
Trees in NoVa are conifers or dicots, which evolved separately millions of years apart. This means the pines and oaks are as closely related as crabs and mice, but they have solved the problems of being tall woody plants in almost identical ways! Softwood v. Hardwood IDENTIFYING TREES How to Identify a Tree
Use sight, touch, smell, taste Use all individual parts – leaves, twigs, bark, flowers, fruit, thorns Look at shape Look at location Look at debris Practice, practice, practice! Tools to Aid in Identification
Your senses – sight, touch, smell, taste Dichotomous keys and field guides Hand lens - details matter! A good memory! Optional: sharp knife or clippers Most important tools: Pattern recognition, attention to detail, memory Leaf Parts Leaf Characteristics
Deciduous or evergreen? Arrangement on stem Simple or compound? Pinnate or palmate lobes, leaflets or veins Margins Base and tip features Special characteristics (smell, texture, stipules, glands, etc.) Types of Leaves
Simple Leaves Needles
Pine needles are clustered
Other conifers have single needles or scales Leaf Margins Leaf Shapes
http://www.clemson.edu/extension/natural_resources/landowner/youth_environ_educa tion/terminology.html Leaf Tips
http://www.clemson.edu/extension/natural_resources/landowner/youth_environ_educa tion/terminology.html Leaf Bases
cuneate — wedge-shaped obtuse — rounded cordate — heart-shaped truncate — squared or abruptly cut off oblique — asymmetrical, unequally sided http://www.clemson.edu/extension/natural_resources/landowner/youth_environ_educa tion/terminology.html Characteristics? Leaf Arrangement
Alternate
Opposite MADCapHorse
Maple, Ash, Dogwood CAPrifoliaceae is a family of shrubs and vines that include honeysuckles Horsechestnut (and buckeyes) No longer includes viburnums and elderberry – common opposite leaved shrubs
Tree Form / Shape
Do you know trees that display these forms/shapes? Habitat – where is the tree growing Bark Characteristics
Terminology is somewhat subjective.
Descriptive terms may include smooth, scaly, ridged, furrowed, fissured, platy, blocky, netted, and more! Characteristics? Honey Locust – Gleditsia triacanthos Twig Characteristics
One Year’s Growth
Leaf scar, w/ Lenticels (the bundle scars tiny dots)
Pith Bud Scar Terminal bud Lateral bud Pawpaw – Asimina triloba Oak – Quercus spp.
Flower Buds PRACTICE Pinus virginiana Virginia pine Pinus strobus Eastern White Pine Fraxinus pennsylvanica Green Ash Quercus alba White Oak Cercis canadensis Eastern Redbud Fagus grandifolia American Beech Carya glabra Pignut Hickory QUESTIONS? Winter Tree Identification
What’s left after the leaves leave? Bark Buds Form Fruit Branching Habitat How do you identify Arlington’s deciduous trees in winter?
• Acer/Maple • Gleditsia/Honeylocust • Gymnocladus/Coffeetree • Aesculus/Buckeye • Halesia/Silverbell • Ailanthus/Tree of Heaven • Juglans/Walnut • Amelanchier/Serviceberry • Liquidambar/Sweetgum • Liriodendron/Tuliptree • Asimina/Pawpaw • Maclura/Osage Orange • Betula/Birch • Magnolia • Carpinus/Hornbeam • Malus/Crabapple • Metasequoia/Dawn redwood • Carya/Hickory • Morus/Mulberry • Castanea/Chestnut • Nyssa/Tupelo • Catalpa • Ostrya/Hophornbeam • Celtis/Hackberry • Oxydendrum/Sourwood • Platanus/Sycamore • Cercis/Redbud • Prunus/Cherry • Chionanthus/Fringetree • Pyrus/Pear • Cladastris/Yellowwood • Quercus/Oaks • Rhus/Sumac • Cornus/Dogwood • Robinia/Locust • Corylus/Hazel • Salix/Willow • Cotinus/Smoketree • Sassafras • Styphnolobium • Crataegus/Hawthorn • Taxodium/baldcypress • Diospyros/Persimmon • Tilia/Linden • Fagus/Beech • Ulmus/Elm • Fraxinus/Ash • Viburnum • Ginkgo Acer/maple negundo,rubrum, saccharum,saccharinum Opposite Flaking/cracked bark Clustered buds Large canopy Streams Sooty mold? Ailanthus/Tree of Heaven
altissima Smooth bark, slightly bumpy Giant bud scars Invaded habitat Will grow out of anything Bark/twigs smell like rancid peanut butter Amelanchier/serviceberry
arborea, canadensis, laevis Striped bark Lichen Remnant fruit Cedar apple rust Small trees Understory Betula/birch
nigra, papyrifera White bark Paper-like bark Thin canopy Medium size Often multitrunk Streams Common landscape plant Carpinus/Hornbeam
Caroliniana, betulus Bark like muscle/sinew Small tree Native: gnarly Non-native: straight and fastigiate Carya/Hickory
cordiformes, glabra, illinoensis, ovata, tomentosa Native bark with tight lines and ridges Pecans and shagbark more variable Buds are often the id Hickory nuts Large tree, wide range Not typically planted Celtis/Hackberry
occidentalis, tenuifolia Warty bark Remnant fruit Uneven form Cercis/redbud
canadensis Stripped/flaking bark Remnant fruit/beans Uneven form Small tree Common landscape Cornus/dogwood
alternifolia, florida, kousa, mas, sericea Opposite (except alternifolia) Blocky/flaky bark Distinctive buds Uneven form Small tree Common landscape Diospyros/persimmon
virginiana, kaki Dark blocky bark (Ebony!) Remnant fruit Medium tree Native rarely planted Non-native produces larger fruit, rarely a large tree Fagus/beech
grandifolia, sylvatica Smooth bark Often vandalized Big tree Fruit husks Buds This one is easy… unless you want to know the difference between the two. Fraxinus/Ash
Americana, pennsylvanica Opposite Diamonds in the bark, often with a V bottom to the ridges. Horns for branches Large tree Common street tree in the North, now declining, due to EAB Ginkgo
biloba Smooth ridges Sharp corners Conservative branching Very slow-growing Stacking buds Gleditsia/honeylocust
triacanthos Witchy branches Scaly bark Giant spikes on naturalized trees Common landscape Uneven form Remnant beans Juglans/walnut
nigra, regia, cinerea Deep ridges Everything around it is dead Walnuts persist on the ground Uneven form Loses leaves very early Liquidambar/sweetgum
styraciflua Blocky, spongy bark Persistent spike balls Corky ridges Huge buds Recently destroyed sidewalk Liriodendron/tuliptree
tulipifera Striped, light bark Persistent flower remnants Don’t forget it’s a magnolia! Duckbill Buds Tallest tree in the east Magnolia
acuminata, stellata, virginiana, soulangeana Smooth bark, with lenticels, often grey Fuzzy buds Remnant fruit Common landscape plant. Small to medium Metasequoia Glyptostroboides Deciduous Conifer Extremely even form Flaky, multicolored bark Opposite, despite not being mentioned in the MAD Cap Horse Remnant fruit Very tall at maturity Morus/Mulberry Alba, rubra Orange in the bark, between ridges Uneven form Messy habit Deep ridges in old trees. Medium to large Invaded habitats Nyssa/Tupelo
sylvatica Blocky bark, similar to Cornus florida Large, long-lived tree Streams Form very even when open-grown, very uneven when wild Someone sat on it Fruit retention Common street tree Ostrya/hophornbeam
virginiana Close, thin strips of bark Exfoliating Common understory Small to medium Platanus/sycamore
occidentalis, x acerifolia Do I really need to tell you what you need to look for? Bark 1 Fruit vs. multiple Streams and streets Prunus/Cherry Serotina, serrulata, x yedoensis, x incamp Flaky, shiny bark Grey to black Lenticels Remnant fruit Native is large, non- native small to medium Can be confused with birches Pyrus/Pear Calleryana, communis, pyrifolia Dark, ridgy bark Branches low Remnant fruit Poor branch attachment Fruit attachment/spines Pyrus calleryana commonly planted/ hated as street tree Quercus/Oak – White oaks
alba, bicolor, montana, stellata Grey bark Strips or deep ridges Acorns often still found in winter, rounded, larger than average red oak (except rubra) Clustered buds More common in natural areas and yards Quercus/Oak – Red oaks
Coccinea, falcata, palustris, phellos, rubra, velutina Darker bark than white oaks, browns and dark greys Clustered buds Small acorns, except for rubra. Often striped More common as street trees Rhus/Sumac
Copallina, typhina Smooth bumpy bark, similar to Ailanthus Fuzzy stems and buds Shrubby to medium tree size Retains berries Robinia/Black locust
pseudoacacia Deep ridged dark brown bark Retain beans Short spines Uneven form Invaded habitats Salix/Willow
nigra, babylonica Wide ridged bark, often flaking Rarely upright Often multitrunk Streamsides Weeping forms in the landscape Taxodium/Baldcypress
distichum, ascendens Very similar to Metasequoia, except: Alternate branching Cone more of a ball Less even form Not as tall Tilia/Linden
americana, cordata, tomentosa Bark Similar to Fraxinus, but alternate branching Very round form Thick, round buds Common street tree Ulmus/Elm
americana, parvifolia, pumila, rubra Stripped bark, very obvious in parvifolia Practically spherical buds Often vase-shaped form Bacterial wetwood Common street tree