Dendrology Lecture

Definition of taxonomy

Science of systematically naming and organizing organisms into similar groups

Definition of classification

Ordering plants into groups with common characteristics in a hierarchical system

Number of plant species worldwide

350,000 to 450,000

Two major cell types in organisms

Prokaryotes and eukaryotes

Key feature of prokaryotes

No true nucleus or membrane around genetic material

Key feature of eukaryotes

True nucleus enclosed by membranes

Five-kingdom system creator

R.H. Whittaker (1969)

Kingdom Monera characteristics

Single-celled prokaryotes without a definite nucleus

Kingdom Protista characteristics

Single-celled eukaryotes that move via cilia, flagella, or amoeboid motion

Kingdom Fungi characteristics

Multicellular eukaryotes without chloroplasts and no locomotion

Non-vascular plants definition

Bryophytes lacking vascular tissues; include mosses, liverworts, hornworts

Vascular plant tissues

Xylem and phloem

Gymnosperm definition

Naked-seeded plants producing seeds on cones or modified bracts

Angiosperm definition

Flowering plants with seeds enclosed within fruits

Difference between monocots and dicots

Monocots have one cotyledon and parallel veins; dicots have two cotyledons and net-like veins

Species definition

Group of organisms that can interbreed and produce fertile offspring

Subspecies definition

Distinct population within a species with minor physical or genetic differences

Variety definition

Variant of a species with minor differences in physical traits

Binomial nomenclature creator

Carl Linnaeus

Holotype definition

Single specimen to which a name is permanently attached

Isotype definition

Duplicate of the holotype collected at the same time and place

Lectotype definition

Specimen designated later when no holotype exists

Neotype definition

Specimen designated when all original material has been destroyed

Meaning of ‘Acer’

Sharp

Meaning of ‘alba’

White

Meaning of ‘rubra’

Red

Gymnosperm diversity

6 orders, 12 families, 83 genera, 1,079 species

Angiosperm diversity

64 orders, 416 families, 13,000 genera, 300,000 species

Tree species diversity worldwide

Approximately 73,000 species

Major parts of a tree

roots, trunk, crown

Function of large roots

anchor the tree and store food

Function of root hairs

absorb water and dissolved mineral salts

Requirement for root survival

Air must be present in the soil

Location and role of pith

Center of trunk; core tissue

Function of heartwood

Provides structural support; composed of dead cells

Function of sapwood

Conducts raw sap from roots to leaves

Definition of xylem

Heartwood + sapwood

Role of cambium

Produces new wood and inner bark; responsible for diameter growth

Function of phloem (inner bark)

Carries food from leaves downward to nourish growing parts

Function of outer bark

Protects inner tissues from injury, drying, disease, and temperature extremes

Role of medullary rays

Store food and conduct water laterally

Process occurring in leaves

Photosynthesis

Products of photosynthesis

Carbohydrates and oxygen

Difference between early wood and late wood

Early wood has large thin-walled cells; late wood has smaller thick-walled cells

What annual rings indicate

Tree age at a given point on the trunk

Definition of shade tolerance

Ability of a species to survive with very low light for long periods

Definition of release

Accelerated growth after canopy opening increases sunlight

Shade-tolerant, long-lived species example

Red spruce

Shade-tolerant but short-lived speices example

Balsam fir

Shade-intolerant species examples

Quaking aspen and paper birch

Dendrology definition

The study of woody plants

Subdisciplines covered by dendrology

Taxonomy, nomenclature, morphology, phenology, ecology, and geographic range of trees

Plant types included in dendrology

Trees, shrubs, and vines/lianas

Key tree identification features

Leaves, bark, fruit, flowers, and habitat

Plant morphology

the study of the structure and form of living organisms

plant physiology

the study of the function of living organisms and their parts

tree ecology

how trees interact with each other and their environment

forest history significance

explains how past disturbances created the modern forest structure

tree definition criteria (heigh & trunk size)

over 20 feet tall at maturity with trunk(s) over 2 inches in diameter

phenology

the study of periodic plant lifecycle events influenced by seasonal and interannual variations in climate

shrub physical characteristics

often have multiple stems, branch at or near ground level, and have a bushy appearance

ecological and environmental benefits of forests

shade, water quality protection, wildlife habitat, soil conservation, and carbon sequestration

socioeconomic benefits of forests

aesthetics, recreation, wood products, and supporting rural economies and jobs

nomenclature

the system of naming organisms according to established scientific rules

Geographic range

the spatial distribution or area where a plant species naturally occurs

liana

a long-stemmed, woody vine rooted in the soil that uses trees to climb to the canopy

Terminal bud

bud located at the tip of the twig, responsible for shoot growth

Axillary bud

also called lateral bud, responsible for branch growth

Leaf scar

a scar left on the twig where a leaf petiole had been attached

Bundle scar

Scars within the leaf scar showing where xylem and phloem passed into the leaf

Node

the region on a twig where one or more leaves are attached

internode

the region on a twig between two successive nodes

Lenticel

porous cells in bark that allow gas exchange between plant interior and atmosphere

Bud scale scars

rings left on a twig when terminal bud scales drop off; useful for aging twigs

Imbricate bud scales

bud scales that overlap one another like shingles on a roof

Valvate bud scales

bud scales that meet edge-to-edge without overlapping

Pith

the central core tissue of a twig, differing in color and texture from wood

Solid pith

continuous, uniform pith with no cross walls or internal cavities

Diaphragmed pith

solid pith divided by distinct transverse cross walls

Chambered pith

Pith with hollow, empty spaces between thin cross walls

Excavated Pith

pith that is completely hollow or empty throughout the center

Spongy pith

pith containing numerous small holes or porous perforations

Xylem primary function

conducts water and dissolved minerals upwards from the roots to the rest of the plant

Xylem cell composition

composed of parenchyma cells, fibers, vessels, tracheids, and ray cells

Vessels (xylem)

long open-ended tubes made of vessel elements; found exclusively in hardwoods

Perforation plate

bar-like strips across vessel element openings that do not obstruct water flow

Tracheids

tapered xylem cells connected by pits; make up almost all xylem in gymnosperms (softwoods)

Wood fibers

modified tracheids in hardwoods that provide mechanical support rather than water conduction

Xylem rays

structures responsible for lateral transport of water and nutrients and food storage

Phloem primary function

conducts sugars and photosynthate food materials throughout the plant

Sieve tubes and sieve plates

conducting cells in phloem arranged end-to-end with porous end walls called sieve plates