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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
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
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
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
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
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.
Simple vs. Compound Leaves
Compound leaves have 2 or more separate leaf blades.
Pinnate or Palmate? Simple or Compound?
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)
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 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 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
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)
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 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
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
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
Aggregate Fruits
• Formed by development of several ovaries produced by one flower
–Exp: raspberries, blackberries
Flower to Fruit
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 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)
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)
Your Turn
What is it?
Monocot or Dicot?
Monoecious or
Dioecious?
Simple, Aggregate, or
Multiple Fruit?
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
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)
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
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
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
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
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