Botany & Physiology

Casey Sharber Canadian County Cooperative

Extension Horticulture Educator

MG Coordinator

Introduction

• Botany- science or study of plants

–Emphasizes how plants function on a cellular/physiology level

• Horticulture- cultivation of plants

Horticulture

• Landscaping and production, marketing of fruits, veggies, and ornamentals

• Branch of ag that deals with intensively cultured plants for food, medicine, or aesthetics

– Individual plants are important

Hort Industries

• Nursery- actual plants

• Floriculture- only flowers

• Olericulture- veggies

• Landscaping- landscape hort

• Interior-scaping- produce and introduce plants into interior setting

• Florists- arranging

• Pomology- fruit and nut culture

• Viticulture- grapes

• Enology- wine

Botany

• Classification

• Plant Structure –Morphology

–Anatomy

• Plant Physiology –Plants functions (photosynthesis,

respiration, transpiration,

hormones)

Classification

• Humans classified plants from the beginning

• Useful to know which plants were edible, poisonous, stimulatory

Common vs. Scientific Names

• Common

–Not governed by any accepted rules

–Variable from region to region

–Not understood by all languages

• Scientific

–Universal language (Latin)

understood

–Difficult to remember

Common vs. Scientific Names

• Example:

–Scientific name: Carpinus caroliniana

–Common Names:

• American Hornbeam

• Blue Beech

• Musclewood

• Water Beech

• Ironwood

Carl Linnaeus (1707-1778) “Father Of Taxonomy”

Carl Linnaeus

• Swedish naturalist, physician

• Created a hierarchy for living things

Nomenclature: the binomial (two-word) naming system

• Based on plant‟s sexual systems and flower structures

Hierarchy • Kingdom

• Division

• Class

• Subclass

• Order

• Family

• Genus

• Specific epithet

• Variety, cultivar

Botanical Plant Classification

• Kingdom- Plantae

• Division- Tracheophyta (higher plants with vascular systems)

–Transport system for water and nutrients

Class

Gymnosperms: conifers, ginkoes, cycads

–Name means “naked seed”

• Seeds lack protective enclosure of flowering plants

–Conifers the most numerous and important

• Oldest tree: Bristlecone Pine (5000 yrs)

• Most Massive tree: Giant Sequoia (375 ft tall, 41 ft diameter)

• Tallest tree: Redwoods

Gymnosperms

Class

Angiosperms: all flowering plants

-name means “covered seed”

-dominant plants of the world

-88% of plant kingdom (260,000 species)

Angiosperms

Plantae

Tracheophyta

Class Gymnosperms Angiosperms

Subclass Dicots Monocots

Hierarchy of Plants

Kingdom

Division

Subclass (Angiosperms)

• Dicots

–2 cotyledons

– Leaves mostly net veined

–Floral parts occur in sets of five or multiples of four or five

–Vascular bundles in rings

–Vascular cambium present

Images from Purves et al., Life: The Science of Biology, 4th Edition

Dicots

Subclass (Angiosperms)

• Monocots

–1 cotyledon

– Leaves mostly parallel veined

–Vascular bundles scattered or in 2+ rings

–No vascular cambium

–Floral parts usually in sets of 3s

Images from Purves et al., Life: The Science of Biology, 4th Edition

Botanical Plant Classification

• Order

• Family

–Generally end in –aceae

–Examples

• Poaceae- Grass Family

• Asteraceae- Sunflower/Composite Family

• Solanaceae- Nightshade Family

• Lamiaceae- Mint Family

Families

• Knowing the characteristics of different families helps you identify plants by narrowing down options

• Examples:

– All plants in Laminaceae (Mint) family have square stems

Flowers of Solanaceae (Nightshade) Family

Tomato Potato Horse Nettle Eggplant

Petunia Datura

Pepper Tobacco

Botanical Plant Classification

• Genus

– Always capitalized and italicized or underlined

– Example: Capsicum (peppers), Lycopersicon, (tomatoes)

• Specific Epithet (Species)

– Always lower case and italicized or underlined

– Example: annuum

• Capsicum annuum- bell pepper

• Capsicum frutescens- Tabasco pepper

Botanical Plant Classification

• Variety- subspecies with marked differences in nature (naturally found); are true to type in succeeding generations

–Exp: Gleditsia triacanthos var. inermis (Thornless Honeylocust)

–Usually seen without the “var.”

Botanical Plant Classification

• Cultivar- selectively bred group of plants within a species that will not remain true in nature

–Can be sexually and/or asexually reproduced

–Bred for special characteristics (i.e. cold hardiness, flower color, size)

Botanical Plant Classification

• Cultivar –Always capitalized in single quotes

and not italicized

–Exp. Cercis canadensis „Forest Pansy‟ • Still a redbud, but has maroon leaves

that fade to green

–Plant variety rights: breeder gets royalties

Other Classification Methods

• Morphological

–Herbaceous: fleshy, soft tissue, dies to the ground in winter, shorter lived

–Woody: dense, sturdy tissue, longer lived, maintains above-ground woody parts

Other Classification Methods

• Morphological

–Deciduous: sheds all leaves at one time each year

–Evergreen: retains leaves year-round

–Semi-evergreen: holds leaves most of the year, generally into winter

Other Classification Methods

• Environmental Adaptation

–Annual: one year to complete life cycle (peas, marigolds, basil)

–Biennial: two years to complete life cycle (carrots, Sweet William)

–Perennial: lives longer than two years (mint, asparagus, grasses)

Other Classification Methods

• Environmental Adaptation

–Hardy: survive low winter temps

–Semi-hardy: intermediate

–Tender: readily damaged by cold

–Warm season

–Cool season

USDA Plant Hardiness Map

Payne County- 6B/7A borderline

Oklahoma Hardiness Zones

6a -10 to -5

F

-20.6 to -23.3

C

St. Louis, MO;

Lebanon, PA

6b -5 to 0 F -17.8 to -20.5

C

McMinnville, TN;

Branson, MO

7a 0 to 5 F -15.0 to -17.7

C

Oklahoma City, OK;

South Boston, VA

7b 5 to 10 F -12.3 to -14.9

C

Little Rock, AR;

Griffin, GA

Other Classification Methods

• Environmental Adaptation

–Hydrophytes: adapted for growth in water or very wet soils

–Mesophytes: intermediate water requirements

–Xerophytes: adapted to seasonal

or persistent drought

Other Classification Methods

• Usage

–Ornamental

• Ex: Roses, etc.

–Food

• Ex: Tomatoes, etc.

–Medicine

• Ex: Herbs (somewhat); mostly

synthetic now

Plant Structures

“What and Where”

Vascular Plants • Root System

– anchor the plant, absorb water and minerals from soil, store energy

• Shoot System – stems and leaves; photosynthetic part of

plant

• Vascular System – Conducts water and minerals to leaves

(xylem) and photosynthetic products

from leaves to rest of plant (phloem)

Vascular System

• Vascular bundles –Xylem = water/minerals

–Phloem = food/sugar

–Vascular cambium (dicots only) • Thin layer of meristematic tissue that

produces xylem to the inside and

• phloem on the outside

• Increases circumference

of stems, roots

Shoot System

• Primary growth

–Occurs close to tips of shoots and roots

– Initiated by apical meristem and results in added length

• Secondary growth

–Thickens stems and roots

– Initiated by lateral meristem

Definitions

Node- point where a leaf is or was attached to the stem

Internode- space between nodes

Bud- undeveloped leaf, flower, or shoot

Petiole- leaf stalk

Apical meristem- growing region at tip of plant (produces length)

Lateral Meristem- growing region on the side of the plant (axillary bud)

Plant Sink- specific area that uses large amounts of energy

Basic Leaf Types

• Ferns have fronds (contain reproductive structures)

• Conifer leaves are typically needle-, awl-, or scale-shaped

• Angiosperm (flowering plant) leaves: the standard form includes stipules, petiole, and lamina (blade).

• Sheath leaves (type found in most grasses).

• Other specialized leaves.

Pinnate vs. Palmate Simple Leaves

Pinnate (as in feather pen)

Palmate

(as in the palm of your hand)

Simple vs. Compound Leaves

Compound leaves have 2 or more separate leaf blades.

Pinnate or Palmate? Simple or Compound?

Pinnately Compound Palmately Compound

Compound Leaves

Bipinnately Compound Leaf

http://www.ibiblio.org/botnet/glossary/a_v.html

Leaf Arrangement

• Opposite- two leaves at each node

• Alternate- only one leaf at each node

• Whorled- 3+ leaves at each node

• Basal- leaves originate from base of plant (basal meristem)

• Fascicle- bundle of leaves (needles)

Leaf Arrangements

Basal Opposite Alternate Whorled

Conifer Leaf Types

Awl-like: juvenile form of Eastern Redcedar

Scale-like: mature form of Eastern Redcedar

Leaf Margins

• Entire- smooth edge

• Serrate- with teeth as a saw

• Sinuate- with wavy indented edge

• Crenate- scalloped edge

• Lobed- rounded but not divided all the way to the midrib

Leaf Margins

Leaf Tips

• Acute- short narrow point

• Acuminate- taper to a sharp point

• Obtuse- rounded or blunt tip

• Obcordate- heart shaped

• Truncate- blunt end; looks like a part has been cut off

Leaf Tips

Leaf Forms

• Deltoid- triangle shaped

• Lanceolate- sharp point like a lance

• Elliptical- shaped like an eye

• Cordate- heart shaped

• Ovate- egg shaped

• Linear- long and narrow

• Peltate- petiole attached to

center of leaf instead of edge

Deltoid Lanceolate

Elliptical Cordate

Ovate Linear

Peltate

Additional Leaf Forms

Types of Root Systems

• Fibrous Roots

• Taproot

• Adventitious Roots- arise from parts other than roots (stems, leaves) –Prop Roots

–Aerial Roots

• Fleshy Roots (Tuberous root)

Types of Root Systems

Fibrous Root

Tap Root - Carrot

Tap Root - Beet

Types of Root Systems

Aerial Roots Adventitious Roots

Types of Root Systems

Prop roots Fleshy storage roots

Specialized Stems

• Rhizomes- underground horizontal stem that produces roots and shoots (iris)

• Stolon- aboveground horizontal stem (bermudagrass, strawberry)

• Tuber- swollen underground stem used for storage (potato)

• Corm- solid, compacted vertical stem formed at base of plant; form

cormels (gladiolus)

Specialized

Stems

Specialized Structures, cont.

• Bulbs

– thick stem with basal roots and fleshy overlapping leaf bases (scales)

– Two types: tunicate and scaly

– Tunicate: each fleshy leaf base completely encloses all parts of bulb within it; has papery covering (tunic)

– Scaly: leaf bases don‟t completely encircle interior part of bulb; no tunic, dry out easily

Bulbs

Flower Structure

Flower Structure

Perfect vs Imperfect

• Perfect: a flower that contains both stamens and pistil

• Imperfect: a flower that lacks either stamens or pistil

Complete vs. Incomplete

• Complete: a flower that contains petals, sepals, stamens and pistil(s)

• Incomplete: a flower that lacks one of the four parts

Combos

• Can have:

–Complete perfect flower

– Incomplete perfect flower

– Incomplete imperfect flower

• Cannot have:

–Complete imperfect

Monoecious vs. Dioecious

• Monoecious- “one house”

–Both male and female flowers on one plant or male and female parts on one flower

• Dioecious- “two houses”

–Male and female flowers on

different plants

Monoecious

Gambel Oak

Quercus gambelii

Squash

Lilium sp.

Dioecious

Yaupon Holly

Ilex vomitoria

Chinese Pistache

Pistacia chinensis

Female Male

Is it a fruit or is it a vegetable?

• Horticultural & Culinary

–A fruit is something sweet and often used for a dessert

• Watermelon is a fruit

• Tomato is a vegetable

• Botanically

–A fruit is a pollinated or ripen

ovary that contains a seed.

• Watermelon & tomatoes are fruit

Fruiting Structures

• Inflorescence: flower structure in entirety, with regard to arrangement

• Types –Solitary

–Corymb

–Umbel

–Spike

–Raceme

–Head

–Spadix

–Panicle

Fruiting Structures

• Fruit - ripened ovary and any associated parts

–Simple fruits

–Multiple fruits

–Aggregrate fruits

Basic fruit

• Pericarp:

–Exocarp

–Mesocarp

–Endocarp

–Seed

Fruit Components

• Pericarp composed of:

–Exocarp- outer layer

–Mesocarp- middle layer

–Endocarp- inner layer

• Distinctive development of

layers for different fruit types

Multiple Fruits

• Formed by development of several flowers which fuse during ripening

–Exp: pineapple, fig, mulberry

Multiple Fruits

Flower to Fruit

Aggregate Fruits

• Formed by development of several ovaries produced by one flower

–Exp: raspberries, blackberries

Flower to Fruit

Simple Fruits

• Formed by development of single pistil or ovary

–Fleshy

–Dry

Simple Fleshy Fruits

• Pome- Produced by compound ovary with many seeds; fleshy mesocarp, endocarp called a core

–Apple, pear, quince

• Berry- pericarp is fleshy throughout

–Tomato, blueberry, eggplant, cranberry

Simple Fleshy Fruits, cont.

• Hesperidium- leathery exocarp and

mesocarp and juicy endocarp with distinct segments

–Grapefruit, orange, lime, lemon

• Drupe- fleshy, one-seeded fruit with

thin exocarp, fleshy mesocarp; seed enclosed in stony endocarp

–Cherry, plum, peach, olive

Simple Fleshy Fruits, cont.

• Pepo- thick, hard exocarp/rind at maturity

•Squash, muskmelon,

watermelon

Simple Fleshy Fruits

Flower to

Fruit

Simple Dry Fruits

• Dehiscent- pericarp splits or dehisces, along definite lines or sutures at maturity

–Follicle: single carpel and dehisces along one suture (milkweed)

–Legume: single carpel that dehisces along two sutures (peanut)

Simple Dry Fruits, cont.

–Silique: two carpels, dehisce along two sutures, fruit divided lengthwise by wall-like structure (radish)

–Silicle: modified silique that is as broad as it is long

–Capsule: product of a compound pistil that dehisces along >2 sutures (okra)

Silique Silicle

Flower to

Fruit

Dehiscent Fruits

Simple Dry Fruits, cont.

• Indehiscent- pericarp does not split or open at maturity; fruits usually only have one or two seeds

–Caryopsis: one-seeded fruit where pericarp and seed coat are fused (corn)

–Achene: one-seeded fruit where pericarp is not fused to seed coat;

can be easily separated (sunflower)

Simple Dry Fruits, cont.

–Samara: one-seeded fruit that has wing-like membranous outgrowth of pericarp (maple, elm)

–Nut: one-seeded fruit with extremely hardened pericarp (oak)

–Schizocarp: compound fruit that has two single-seeded achene-like “mericarps”, break apart easily (carrot, dill)

Indehiscent Fruits

Your Turn

What is it?

Monocot or Dicot?

Monoecious or

Dioecious?

Simple, Aggregate, or

Multiple Fruit?

Plant Physiology

The Cell, Photosynthesis, Respiration, and Transpiration

The

Plant

Cell

Parts of the Plant Cell

Vacuole- contains water, nutrients, wastes; regulates cell turgor

Nucleolus- contains DNA of cell

Chloroplast- contains chlorophyll (center for photosynthesis and gives green color)

Mitochondrion- “cellular power plants” in respiration; convert organic materials into energy (ATP)

Cell wall- contains cellulose, protein, lignin to support the plant

Ribosome- composed of RNA; builds protein from genetic instructions

Leaf Tissue Anatomy

Tissue Location and Structure Function

Upper cuticle

Not a tissue......a waxy covering on the

surface of the leaf

Aids in reducing water loss by decreasing

transpiration and protects against insect invasion

Upper epidermis

This tissue is made up on a thin layer of

cells which do not contain chloroplasts

and they are transparent. Found below

the cuticle.

This tissue also aids in reducing water loss, allows

light to pass through to the palisade layer, prevents

gas exchange and secretes the waxy cuticle that

covers the leaf.

Palisade layer

The area is called the palisade

mesophyll. A densely packed area of long

cells which contain high numbers of

chloroplasts for photosynthesis. It is

located near the top of the leaf (and under

the upper epidermis) for absorption of

sunlight

The palisade layer is responsible for

photosynthesis. Due to its location in the upper

portion of the leaf maximum light can be absorbed

Spongy layer

This area is known as the spongy

mesophyll and it contains loosely packed

cells with spaces of air in between. The

cells contain only a few chloroplasts.

The spongy mesophyll is located below the palisade

mesophyll and the spaces between the cells allow

for the exchange of gases. Some photosynthesis

also occurs here.

Lower epidermis

This tissue contains stomata or stomal

pores which are openings on the bottom

surface of the lower epidermis. Each

stoma is surrounded by a guard cell that

controls the opening and closing of the

stoma.

Located just below the spongy mesophyll to allow

for optimum exchange of gases. The lower surface

of the leaf receives less light and heat which helps

prevent water loss from the plant.

Veins Distributed throughout the leaf often near

the middle in order to be near all cells.

Transports the products of photosynthesis and raw

materials.

Lower cuticle

Not a tissue......a waxy covering on the

surface of the leaf. Usually thinner than

the upper cuticle.

Aids in reducing water loss by decreasing

transpiration and protects against insect invasion

Photosynthesis

• Biochemical process in which plants utilize the energy of the sun to produce food

• Energy requiring reaction

• Occurs only in chloroplasts within chlorophyll

• Only occurs during the day

Factors affecting

Photosynthesis

Genotype (CO2 fixation efficiency)

Developmental stage

Canopy structure

Environmental conditions (CO2, water, minerals, temps)

So how does a

tree live in the

winter with no

leaves?

Respiration

Occurs in all living cells in mitochondria

Occurs in both light and dark

The opposite of photosynthesis: glucose

and other compounds are oxidized to

produce carbon dioxide, water, and

chemical energy.

Carbs produced in Ps used to fuel plant

functions/reactions

Increases with temperature

Photosynthesis

produces food

stores energy

uses water

uses carbon dioxide

releases oxygen

occurs in sunlight

Respiration

uses food

releases energy

produces water

produces carbon dioxide

uses oxygen

occurs in the dark as well

as light

Ps versus R

Gross Ps – R = Net Photosynthesis (Pn)

You want to maximize Pn

In high light, Ps > R = growth

In medium light, Ps=R = no growth

In low light, Ps < R = death

Transpiration

(Plant Sweat)

Loss of water from the plant surfaces

(leaves)

Mostly occurs from stomata

Cools the plant

95% of absorbed water lost to

transpiration

Driving force behind transpiration stream

Transpiration Stream

The loss of water from the

leaf cells pulls water in

from the xylem, this pulls

water up the xylem, and

this in turn pulls water

from the ground tissue of

the roots causing water

to be pulled in from the

soil.

Transpiration Stream

Water evaporating from leaves (stomata) drives movement of water from the roots

Water particles have high adhesion to one another, creating a continuous “stream” from the roots to the leaves

Stomata determine amount of transpiration: turgid= open, more transpiration; flaccid= closed, less transpiration Most plants close stomata during the night (cactus

are an exception; adaptation to harsh envir.)

Transpiration

Different factors affect rate of transpiration

Plant size, light intensity, humidity, wind speed,

temperature, water supply

Humidity inside leaf= 100%, humidity outside

leaf always lower, so water will move from

higher conc. to lower (diffusion); water loss is

inevitable

Higher temps= more water loss

Lower humidity= more water loss

Environmental Factors

That Affect Plant Growth

Light

Temperature

Water

Nutrition

Light

Quantity

Intensity or concentration of sunlight

Varies with season

More (to a point) = more Ps

Quality

Color/wavelength

Blue and red light most important

Blue= vegetative growth

Red+Blue= flowering

Light

Duration

Photoperiod, hours of light per day

Triggers flowering

Short-day= flower with less than12 hrs light

(mums, poinsettias)

Long-day= flower with greater than 12 hrs light

(poppy, veggies like beets, radish, lettuce)

Day-neutral= flower regardless of light (petunia)

Temperature

Ps increases with temp to a point and decreases with low temps

Respiration increases with temp

Transpiration increases with temp

Flowering may be partially triggered by temps (bulbs-forcing)

Sugar storage- low temps increase storage

Dormancy- higher temps after a period of lower temps can break dormancy

Water

Essential for Ps

Maintains turgor pressure in cells/ rigidity

of plant

Regulates transpiration

Relative humidity important

Cools plant through transpiration

Solvent for minerals moving into plant

Nutrition

Elements essential for plant growth

Macronutrients

Large quantities

N, P, K, Mg, Ca, S; C, H, O

Micronutrients

Small quantities

Fe, Zn, Mo, Mn, B, Cu, Co, Cl

Plant Hormones

Plant Hormones

Substances that stimulate the growth and

differentiation of cells, tissues, and

organs.

Largely determine phenotype (visible

characteristics) of plants

Are natural, whereas Plant Growth

Regulators (PGRs) are synthetic

Major Plant Hormones

Auxins

Gibberellins

Cytokinins

Ethylene

Abscisic acid

Plant Hormones

Must meet following criteria:

Endogenous (originates within plant)

Organic compound

Occurs in low concentrations (<1ppm)

Translocated to site of action

Cannot be nutrient or vitamin

Auxins

Cell elongation

Phototropism

Cell division

Differentiation

Apical Dominance- auxins produced in the apical region

Promote or inhibit abscission

Dropping of plant part

Gibberellins

Cell elongation

More dramatic effect than auxins

Cell division

Vascular cambium, new phloem, interacts

with auxins to create both xylem and

phloem

Seed Germination

Affect flowering, fruit set, fruit growth,

maturation, and ripening

Cytokinins

Cell enlargement

Swelling of cells, not elongation

Differentiation

Cytokinesis means process of cell division

Used extensively in tissue culture with auxins

High cytokinin: low auxin = shoot growth

High auxin: low cytokinin = root growth

Equal levels of both = callus growth (undifferentiated mass)

Reduce Senescence

Slow chlorophyll breakdown, increase biosythesis

Overcoming of bud/seed dormancy

Ethylene

A gas unlike others which are in solution

Stunting, Curling of leaves

Epinasty= curling down

Induction of Adventitious roots

Promotes abscission

“Aging hormone”- fruit ripening

Used extensively commercially

Abscisic acid

Inhibitor

Promotes and maintains bud/seed

dormancy

Stress hormone

Causes stomata to close

References

The Biology of Horticulture. 1993. Preece, J. and Read, P.

Manual of Woody Landscape Plants. 1998. Dirr, M.

Landscape plants for Texas and environs. 2002. Arnold, M.

Introductory Horticulture Lab Manual. 2002. Peffley, E., Durham, R., McKenney, C., and Wilmington, J.

California State University website http://arnica.csustan.edu/boty1050/Vascular/vascular_plants.htm

University of Maryland website http://www.agnr.umd.edu/

Bethel University website http://www.bethel.edu/~johgre/bio114d/HigherVasculars.html

Wikipedia website www.wikipedia.com