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Unit 5: Plant Science
Introduction to Agriscience
Plant Science defined

The application of scientific principles to
the growth and management of plants.
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Agronomy – crops
Forestry – trees
Horticulture – ornamentals and fruits
Floriculture – flowers
Turf – grasses
Parts of a Plant
The Four Basic Parts of Plants
 Leaves
 Stems
 Roots
 Flowers
Leaves

Function

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Manufactures food for the plant by
using light energy. (photosynthesis)
Serves as site of respiration and
transpiration.
Useful for identification of the plant
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Margin (leaf edge)
Shape
Arrangement
Leaves
Stems
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Function
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Supports other plant parts such as….
Leaves
 Flowers
 Fruit
 Transports water and nutrients
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Two types of above ground stems
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Woody – hard with bark covering
Herbaceous – soft with no bark
Stems continued
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Node
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Point on a stem where leaves, flowers,
roots, or branches originate from.
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Contains bud
Internode
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Section of a stem between nodes
Root Systems
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Function
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Anchor the plant
Take in water & nutrients
Hold soil
Store food
Types of roots
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Fibrous
Tap
Adventitious
Fibrous Roots
Primary root with many secondary
branches
 Shallow roots ideal for water absorption
(larger area)
 Most effective in controlling erosion
 Cause more damage to
structures/utilities

Tap Roots
Continuation of primary root
 Ideal for anchorage
 Penetration is greater for water intake
 Can be used to store food

Adventitious Roots
Do not originate from the primary root
 Form on stems, branches, leaves, or old
woody roots
 Include aerial and stilt roots
 Can form the largest part of the root
system of some plants
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Roots
Flowers
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Function
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Contain the
sexual organs for
the plant.
Produce seeds &
fruit.
Attract insects
with smell/color
for pollination
Parts of the Flower

Sepals
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Outer covering of the
flower bud.
Protects the stamens
and pistils when
flower is in bud
stage.
Collectively known as
the calyx.
Parts of the Flower
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Petals
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Brightly colored
Protects stamen &
pistils.
Attracts pollinating
insects. (color)
Collectively called
the corolla.
Parts of the Flower (Stamen)

Male reproductive part
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Anther
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Filament
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Manufactures pollen.
Supports the anther.
Pollen
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Male sexual reproductive cell.
Parts of the Flower (Pistil)
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Female reproductive
part
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Ovary
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Enlarged portion at
base of pistil.
Produces ovules
which develop into
seeds.
Stigma
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Usually “sticky”
Receives the pollen.
Parts of the Flower (Pistil)

Style
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Connects the stigma with the ovary.
Supports the stigma so that it can be
pollinated.
Pollen tube grows through toward ovary
Nectaries
Responsible for producing nectar which
is composed mainly of sugars
 Internal – at the base of the pistil
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Insects/animals brush against reproductive
parts for pollination
External – on leaf stem, midrib, or
margin
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Attracts predatory insects/animals
Parts of the Flower
Imperfect Flower
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Male or female
reproductive organs,
but not both.
Example:
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A male flower has
sepals, petals, and
stamen, but no pistils.
A female flower has
sepals, petals, and
pistils, but no stamen.
Perfect Flowers
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Contains both male
and female
reproductive
structures.
Incomplete Flowers
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Missing one of the
four major parts of
the flower.
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Stamen
Pistil
Sepal
Petal
Complete Flowers
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Contains male and
female reproductive
organs along with
petals and sepals.
Flowers
Imperfect flowers are always
incomplete but……..
 Perfect flowers are not always complete
and……..
 Complete flowers are always perfect.
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Groups of flowering plants
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Monocot
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Single cotyledon
Flower parts in multiples of threes
Leaf veins parallel
Fibrous roots
Vascular bundles scattered
Groups of flowering plants
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Dicot
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Two cotyledons
Flower parts in multiples of four or five
Leaf veins branching
Tap roots
Vascular bundles in a ring
Monocot vs. Dicot
Pollination vs. Fertilization
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Pollination – the transfer of pollen from the
anther to the stigma (allows fertilization to
take place)
Self pollination – when the pollen comes from
the same flower or plant
Cross pollination – when the pollen comes
from a different plant
Fertilization – union of the nuclei of the pollen
and the nuclei of the ovule (produces seeds)
Parts of a Seed
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Seed Coat
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Protects the seed.
Sometimes very hard & difficult to
germinate.
Horticulturists assist germination by
scarifying the seed coat or damaging the
seed coat to promote germination.
Stratifying seeds mimics the freeze/thaw
cycle of nature.
Parts of a Seed
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Endosperm
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Supplies food for
the germinating
seed.
Embryo
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The young plant.
Propagation
Propagation
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What is Propagation?
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Increasing the number of a plant species
or reproduction of a species.
Two Types of Propagation
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Sexual
Asexual
Sexual Propagation
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The use of seed for reproducing plants.
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Allows the most variation of any
propagation method.
Only way to obtain new varieties and
increase hybrid vigor of the plants.
Less expensive & quicker than other
methods.
Occurs through pollination.
Asexual Propagation
Use of a part of a plant for reproducing
new plants, other than the seed. (leaf,
stem, root, tissue culture)
 Also called vegetative propagation.
 The new plant is an exact duplication of
the parent plant. (same DNA)
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Methods of Asexual Propagation
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Cuttings
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Vegetative parts that
the parent uses to
regenerate itself.
Examples:
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Leaf cuttings.
Root cuttings.
Stem cuttings.
Root hormones are
applied to speed up
root development.
Methods of Asexual Propagation
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Layering
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The stem is
encouraged to root
while still attached to
the parent plant.
Examples:
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Simple layering.
Tip layering.
Air layering.
Methods of Asexual Propagation
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Division
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Dividing or separating
the main part of the
plant into smaller parts.
Grafting
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Joining two plants
together so they grow as
one.
T-Budding is the most
common method.
Methods of Asexual Propagation
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Tissue Culture
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Also called
micropropagation.
The use of a very
small and actively
growing part of the
plant to produce a
high number of new
plants.
Cloning achieved by
tissue culture.
Plant Life Cycles
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Annuals – complete life cycle in one
season
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Warm season – spring and summer
Cool season – fall and winter
Biennial – complete life cycle in two
years
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Vegetation produced the first year and fruit
produced the second year
Plant Life Cycles
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Perennial – live year after year
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Herbaceous – usually die back in winter
and grow new vegetation each year
Woody – do not die back because they
withstand the colder temperatures
Photosynthesis
Photosynthesis
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Process in which light energy is
converted to chemical energy in the
form of a simple sugar (glucose).
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Chlorophyll & chloroplast are essential.
Carbon dioxide is used to manufacture
food for plant and releases oxygen
necessary for animal life at the same time.
Photosynthesis reaction
Photosynthesis
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Rate of photosynthesis (food making)
process depends on & varies with the….
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Light intensity
Temperature
Concentration of carbon dioxide in the
atmosphere.
Carbon Dioxide
Shortage of carbon dioxide causes a
low rate of photosynthesis.
 Enclosed greenhouses can have a
shortage of carbon dioxide.
 A CO2 generator might be used to
correct a shortage of carbon dioxide in
the greenhouse.
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Light
Low light hinders plant growth.
 A dark room reduces the photosynthetic
rate and plants will have stunted
growth and yellow leaves.
 All plants have a preferred range, but
they can adapt to various levels of light
brightness (intensity).
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Temperature
Affects the process of photosynthesis.
 Best rate of photosynthesis occurs
between 65-85 degrees Fahrenheit.
 Extremes of temperature can
completely stop the process.
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Respiration
Respiration
The process through which energy
stored in organic molecules is released
to do metabolic work
 Conducted in all living cells, it is
controlled by enzymes, and releases
carbon dioxide and water
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Respiration reaction
Respiration
Plants “breathe” through their leaves.
 The underside of the leaves have
microscopic pores called stomata.
 Air passes in and out of the leaf through the
stomata.
 Respiration takes place 24 hours a day.
 Each cell and the plant as a whole take in
oxygen and gives off carbon dioxide.
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Transpiration
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Process in which excess water is given
off by plants.
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Water escapes through stomata.
Rate depends on light, temperature,
humidity, wind, and water supply.
Competition
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Process in which two organisms are
trying to use the same resource.
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Water
Space
Sunlight
Nutrients
Competition
Intraspecific – competition between
organisms of the same species
 Interspecific – competition between
organisms of different species
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Plant Nutrition
Nutrients
There are 16 chemical elements essential
for plant growth and production.
 Divided into non-mineral and mineral
classes and into macronutrient and
micronutrient classes
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Nutrients
Non-mineral – provided by air and water
 Mineral – provided by soil and fertilization
 Macronutrients – needed in large quantities
for plant growth and production.
 Micronutrients – needed in small quantities
for certain reactions within the plant such as
hormone and chlorophyll production.
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Macronutrients (Air/Water)
Carbon – C
 Hydrogen – H
 Oxygen - O
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Macronutrients (Soil)
Nitrogen – N (major)
 Phosphorus – P (major)
 Potassium – K (major)
 Calcium – Ca (lime)
 Magnesium – Mg (lime)
 Sulfur - S
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Micronutrients
Boron - B
 Copper - Cu
 Chloride - Cl
 Iron - Fe
 Zinc - Zn
 Manganese - Mn
 Molybdenum - Mo
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Fertilizers
Fertilizers
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Complete fertilizer
must contain the
three nutrients.
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Nitrogen
Phosphorus
Potassium
Fertilizers
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Come in various forms….
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But most nutrients within a fertilizer must become
in liquid form (soluble) to be used by plants.
Organic Fertilizers
Include animal manures & compost
made with plant or animal products.
 Examples:
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Dried & pulverized manures.
Bone Meal (4-12-0)
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Phosphorus is the primary element
Soybean Meal (7-2-1)
Blood Meal (12-0-0)
Fertilizers
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Organic Fertilizers
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Usually slow acting and long lasting forms
of nitrogen but lacking in the other primary
nutrients.
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Except bone meal.
Inorganic Fertilizers
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Have a higher analysis of soluble nutrients
that have been blended together for a
specific purpose.
Fertilizer Application
Broadcasting or spreading evenly over
the entire surface is used on turf and
home lawns.
 Side-dressing is done by placing
fertilizer in bands about 8 inches from
the row of growing plants.
 Foliar application is the spraying of
fertilizer onto the leaves of plants.
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pH of Growing Media
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pH has the most impact on the availability of
nutrients in the soil/media.
pH Scale
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Ranges from 0 to 14.
Indicates the level of acidity or alkalinity.
7 is considered neutral.
Everything greater than 7 is considered alkaline
(basic).
Everything less than 7 is considered acidic.
pH Scale
pH Scale
Amending the pH
Alkaline soils can be made more acidic
by lowering the pH value with sulfur or
aluminum sulfate.
 Acidic soils can be made more alkaline
by raising the value with lime.
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Lime usually applied as finely ground
dolomitic limestone that supplies both
calcium and magnesium.
Other factors that affect plant
growth and production
Competition – when two plants are
striving to get nutrients, water,
sunlight, or space from one another.
 Insects – damage plants and fruit
 Climatic catastrophes – temperature,
hurricanes, tornadoes, drought, flood,
freeze
 Diseases – damage plants and fruit
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Growing Media
Types of Growing Media
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Soil
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Top layer of the Earth’s surface.
Primary medium for cultivated plants.
Types of Growing Media
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Sphagnum Moss
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Used for encouraging root growth under
certain conditions. Holds water well, but drains.
Types of Growing Media
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Perlite
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Volcanic ash used
for water
adhesion and
aeration in media
mixes.
Types of Growing Media
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Vermiculite
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A mineral; mica-type material used for water
holding in media mixes.
Types of Growing Media
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Peat Moss
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Used in media
mixes of various
types for water
holding capacity
and drainage.
Types of Growing Media
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Bark
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Used in media
mixes of various
types for water
retention,
drainage, and
aeration.
Types of Growing Media
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Compost
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Decomposed
organic matter,
contains most
nutrients needed
by plants.
Careers
Floriculture Careers
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Related to flower production and use.
Floriculture Careers
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Floral designer
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Flower grower
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Designs flowers for a
florist or business.
Produces flowers used in
floral design.
Greenhouse manager
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Manages the production
process for a flower
grower.
Floriculture Careers
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Retail florist
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Floral business that
furnishes flowers to
the general public.
Wholesale florist
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Floral business that
furnishes flowers and
supplies to a retail
florist.
Nursery/Landscape Careers
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Related to the use & production of plants for
aesthetic purposes.
Plants may be used around homes,
businesses, parks, etc.
Nursery/Landscape Careers
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Greenskeeper
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Landscaper
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Takes care of golf
course turf.
Installs plants in
various locations.
Landscape architect
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Design plans for
plant installation.
Nursery/Landscape Careers
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Nursery operator
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Grows trees and
shrubs needed for
landscaping.
Turf farmer
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Grows turfgrass
for sale.
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FFA Advisor
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High School