Download Intro to Plants

Kingdom
Plantae
The Body’s Organization
Each level represents a different compartment
Organism
Organs
Tissues
Cells
Organelles
Multicellular Organisms
700-500 mya
Eukaryotic Cells
1.7 bya
Major
Evolutionary
Events in the
Origin of Life
First Cells
Prokaryotes
“the animation of matter”
3.5 bya
Primordial Soup
Domains:
Eubacteria
Archaea
Kingdoms:
Eukarya
Animal
Fungi
Archaebacteria
Plant
Protist
Eubacteria
Common
ancestor
Introduction to Plants
• Based on weight, plants are the dominant
group of organisms on land. This is called
biomass.
• Most plants are photosynthetic.
– They produce organic materials from inorganic
materials by photosynthesis.
• A few plant species live as parasites.
– Many parasitic plants cannot photosynthesize.
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Importance of Plants
Asthetics
Medicine
Food
Industrial products
Recreation
Air quality
Water quality
Climate
Fish and wildlife habitats
Ecosystem
Introduction to Plants
• Plants probably evolved from multicellular
aquatic green algae that could not survive on
land. Through mutations and natural
selection, plants changed enough and some
survived. (Evolutionary viewpoint)
• Multicellularity enabled plants to develop
features that helped them live more
successfully on land.
Introduction to Plants
Before plants could thrive on land, they had to
be able to:
– Absorb nutrients from their surroundings.
– Prevent their bodies from drying out.
– Reproduce without water to transmit sperm.
Absorbing Nutrients
• On land, most plants take nutrients from the
soil with their roots.
• Fungi have helped land plants to get
nutrients from Earth’s rocky surface.
– Symbiotic relationships referred to as mutualism
between fungi and the roots of plants
are called mycorrhizae.
– Today, about 80% of all plant
species form mycorrhizae.
Preventing Water Loss
• The first plants lived at the edges of bodies of
water, where drying out was not a problem.
• A watertight covering, which reduces water
loss, made it possible for plants to live in drier
habitats.
– This covering, called
the cuticle, is a waxy
layer that covers the
non-woody
aboveground parts
of most plants.
Preventing Water Loss
• The cuticle does not let oxygen or carbon
dioxide pass through it.
• Pores called stomata permit plants to
exchange oxygen and carbon dioxide.
– Stomata extend through the cuticle and the
outer layer of cells (epidermis).
• A pair of guard cells border
each stoma.
• Stomata open and close
as the guard cells
change shape.
Preventing Water Loss
Reproducing on Land
• Aquatic algae reproduce sexually when sperm
swim through the water and fertilize eggs.
• The sperm of most plants must be able to
move without water.
• In most plants, sperm are enclosed in
a structure (pollen) that keeps
them from drying out.
• Pollen permits the sperm
of most plants to be carried
by wind or animals rather
than water.
Four Types of Plant Tissue
A growing plant is like building a house!
• Building a House
1. Foundation is laid
2. Construction of the
frame
3. Installation of
plumbing, heating,
etc
4. Waterproof walls
and roof
5. Food stored in
appropriate places
• Building a plant
1. Meristems give rise to all
tissues
2. Three tissue systems give
rise to the major organs of
a plant
3. Installation of the vascular
tissue (plumbing)
4. Installation of dermal
tissues
– covering, skin
5. Installation of ground
tissue
– parenchyma
Meristematic Tissue
• Meristems are regions of cell division
• Main difference between animals and plants
• Birds and mammals stop growing at maturity,
although certain cells get replenished (skin)
• Plants have the ability to keep growing their
entire lives
• Meristems make it possible to grow a new
plant from a cutting
• Growth in plants is the counterpart (to some
extent) to movement in animals
Epidermis – stoma, trichomes, & root hairs
http://www.ucd.ie/botany/Steer/hair/roothairs.html
Cell Division: Mitosis (nuclear division)
+ Cytokinesis (cytoplasmic division)
1. Interphase
2. Prophase
3. Metaphase
4. Anaphase
5. Telophase
6. Cytokinesis
Illustration from:
Vascular Tissue, Seeds and Flowers
• One of the most important structures in plants
is the conducting tissues that move water and
other materials through the plant body.
• Without these structures, plants would remain
very small.
Advantages of Conducting Tissue
• Some plants are small.
– Materials are transported within their bodies by
osmosis and diffusion.
• Specialized cells that transport water and
other materials within a plant are found in
vascular tissues.
• The existence of vascular tissue allows for
larger and more complex plants.
Advantages of Conducting Tissue
• The larger, more complex plants have a
vascular system.
– A system of well-developed vascular tissue that
distributes materials more efficiently.
• Three groups of plants alive today lack a
vascular system.
– These plants are called nonvascular plants.
• Plants that have a vascular system are called
vascular plants.
Advantages of Seeds
• A seed is a structure that contains the embryo
of a plant.
– An embryo is an early stage in the development
of plants and animals.
• Most plants living today are seed plants.
– Vascular plants that
produce seeds.
Advantages of Seeds
• Protection
– Seeds are surrounded by a protective cover
called the seed coat.
– The seed coat protects the embryo from drying
out and from mechanical injury and disease.
• Nourishment
– Most kinds of seeds have a supply of nutrients
stored in them.
– These nutrients are
a ready source of
nourishment for a
plant embryo as it
starts to grow.
Advantages of Seeds
• Plant Dispersal
– Seeds disperse (spread) the offspring of seed
plants.
– Many seeds have structures that help wind,
water, or animals carry them away from their
parent plant.
– Dispersal prevents competition
for water, nutrients, light, and
living space between parents
and offspring.
Advantages of Seeds
• Delayed Growth
– The embryo in a seed is in a state of suspended
animation.
– Most seeds will not sprout until conditions are
favorable.
• Such as when moisture is present
and the weather is warm.
– Seeds make it possible
for plant embryos to survive
through unfavorable periods
such as droughts or
cold winters.
Advantages of Flowers
• The flower is a reproductive structure that
produces pollen and seeds.
• Most plants living today are flowering plants –
seed plants that produce flowers.
– The pollen of the first seed plants are believed by
evolutionists to be carried by wind.
– Large amounts of pollen are
needed to ensure cross-pollination
by wind – an inefficient system.
Advantages of Flowers
• Many flowers attract animals, such as insects,
bats, and birds.
• Tiny pollen grains stick to animals, which carry
pollen directly from one
flower to another.
• Flowering plants that
are pollinated by animals
produce less pollen,
and cross-pollination
can occur between
individuals that live far apart.
Plant Life Cycles
• Plants have life cycles in which haploid plants
that make gametes (gametophytes) alternate
with diploid plants that make spores
(sporophytes).
– A life cycle in
which a
gametophyte
alternates with
a sporophyte is
called alternation
of generations.
Alternation of Generations
Vascular-Plant Sporophyte
• Vascular System
– Larger bodies require an efficient vascular system
for transporting materials internally.
– The sporophytes of vascular plants have two
types of vascular tissue.
– Each type of vascular tissue contains strands of
long, tube like cells that are lined up end to end
like sections of pipe.
– These strands of
cells transport water
and nutrients within
a plant’s body.
Vascular-Plant Sporophyte
– Soft-walled cells transport organic nutrients in a
tissue called phloem.
– Hard-walled cells transport water and mineral
nutrients in a tissue called xylem.
• The walls of the water-conducting cells in xylem
are thickened, which helps support the plant
body.
– This makes it
possible for
vascular plants
to grow to
great heights.
Vascular-Plant Sporophyte
Vascular-Plant Sporophyte
• Distinctive Body Form
– Nearly all plants have a body that consists of a
vertical shaft from which specialized structures
branch.
– The part of a plant’s body
that grows mostly upward
is called the shoot.
– In most plants, the part
of the body that grows
downward is called
the root.
Vascular-Plant Sporophyte
– Zones of actively dividing plant cells, called
meristems, produce plant growth.
– The vertical form of the plant
body results as new cells are
made at the tips of the
plant body.
Kinds of Plants
•Nonvascular
•Vascular without Seeds
•Vascular with Seeds
Kinds of Plants
•Nonvascular
•Vascular without Seeds
•Vascular with Seeds
Nonvascular Plants
• Nonvascular plants do not
have a vascular system
for transporting water and
other nutrients within their
bodies.
• All nonvascular plants
lack true roots, stems,
and leaves.
– Although most have
structures that resemble
them.
Features of Nonvascular Plants
• Require Water for Sexual Reproduction
– Nonvascular plants must be covered by a film of
water in order for fertilization to occur.
– Eggs and sperm form in separate structures,
which are often on separate plants.
– The gametophytes grow
in mats tightly covered
by a film of water; sperm
can easily swim to
neighboring individuals
and fertilize their eggs.
Classification of Nonvascular
Plants
• Bryophytes
Small with leaflike, stemlike, and rootlike
structures. Mosses usually only grow to 1
inch. Disseminated by spores:
mosses, liverworts, hornworts
Mosses
Bryophyta
Liverwort
Hepatophyta
Hornwort
Anthocerophyta
Bryophyte Reproduction
Mosses and Medicine
• Moss has been used as an antiseptic for
centuries.
• In World War I, moss was used to treat
soldier’s wounds in emergency situations.
• The antiseptic qualities result from moss’
natural absorbency and acidity.
Mistaken for Mosses
• A variety of plants and plantlike organisms
are mistakenly called mosses.
– Irish moss is a red alga.
– Spanish moss is
a flowering vascular plant.
– Reindeer moss is
a lichen.
Kinds of Plants
•Nonvascular
•Vascular without Seeds
•Vascular with Seeds
Seedless Vascular Plants
Features of Seedless Vascular Plants
• Vascular System
– Have both xylem and
phloem.
– The water-conducting cells in
the xylem are reinforced with
lignin, a major part of wood.
– Lignin bonds with cellulose to
make a sturdy, strong cell
walls.
– Because of their vascular
system, they grow much larger
than nonvascular plants and
also develop true roots, stems,
and leaves.
Classification of Seedless Vascular
Plants
• Ferns
– Phylum Pterophyta are the most common and
most familiar seedless vascular plants.
– Ferns grow throughout
the world, but they are
most abundant in the
tropics.
– The plants that are
recognized as ferns
are sporophytes.
Reproduction of Seedless Vascular
Plants
– Most fern sporophytes have rhizomes that are
anchored by roots and leaves called fronds.
• The coiled young leaves of a fern are called
fiddleheads.
– Spores are produced
in sporangia that
grow in clumps called
sori on the lower side
of fronds.
Sori
– The gametophytes of ferns are flatted, heartshaped green plants that are usually less than 1
cm across.
Kinds of Plants
•Nonvascular
•Vascular without Seeds
•Vascular with Seeds
 Gymnosperms
 Angiosperms
Gymnosperms
• Seed plants whose seeds
do not develop within a
sealed container (a fruit).
• The word comes from
the Greek words
gymnos, meaning
“naked,” and sperma,
meaning “seed.”
Features of Gymnosperms
• Seeds
– All gymnosperms produce
seeds.
– Seeds protect plant
embryos, provide them with
nutrients, and permit them
to survive long periods of
unfavorable conditions.
– In some plants, seeds also
disperse new plants far from
their parents.
Features of Gymnosperms
• Greatly Reduced Gametophytes
– All seed plants produce very tiny gametophytes of
two types.
• Male and female.
– The gametophytes
form within the tissues
of the sporophytes.
– Grains of pollen are
male gametophytes.
– Female gametophytes
form within structures
that become seeds.
– In all but one species of gymnosperm, male and
female gametophytes develop in male and female
cones.
Features of Gymnosperms
• Wind Pollination
– The sperm of gymnosperms do not swim
through water to reach and fertilize eggs.
– Instead, the sperm are carried to the structures
that contain eggs by pollen,
which can drift on the wind.
– Wind pollination makes
sexual reproduction
possible even when
conditions are very dry.
Kinds of Gymnosperms
• Conifers
– Phylum Coniferophyta are the most familiar and
most successful gymnosperms.
– Conifers have leaves that are either needle-like or
reduced to tiny scales.
• These leaves are an
adaption for
limiting water loss.
Kinds of Gymnosperms
– Some of the tallest living plants, the redwoods of
coastal California and Oregon are conifers.
– The oldest trees in the world are thought to be
bristlecone pines, a species of conifer that grows
in the Rocky Mountains and Great Basin.
• Some bristlecone pines are about 5,000 years old.
– Vast forests of conifers
grow in cool, dry regions
of the world.
Kinds of Gymnosperms
• Cycads
– Phylum Cycadophyta have short stems and
palm-like leaves.
– Cones that produce pollen and those that
produce seeds develop on different plants.
– Cycads are widespread
throughout the tropics.
Kinds of Plants
•Nonvascular
•Vascular without Seeds
•Vascular with Seeds
 Gymnosperms
 Angiosperms
Angiosperms
• Most seed plants are flowering plants or
angiosperms.
• Angiosperms produce seeds that develop
enclosed within a specialized structure
called a fruit.
• The word comes from
the Greek words
angeion, meaning
“case,” and sperma,
meaning “seed.”
Features of Angiosperms
• Flowers
– The male and female gametophytes of
angiosperms develop within flowers which promote
pollination and fertilization more efficiently than
do cones.
– Some flowers, such as
roses, are brightly colored
or have strong scents.
• This attracts insects and
other animals that carry
pollen and increases the
likelihood of crosspollination,
which often occurs before
the flowers open.
Features of Angiosperms
• Fruits
– Although fruits provide some protection for
developing seeds, their primary function is to
promote seed dispersal.
– The angiosperms produce many different types of
fruits, which develop from parts of flowers.
– Many fruits are eaten by animals and pass
undigested from the animals’ bodies.
– Other fruits have structures that help them float on
wind or water.
– Some fruits even forcefully eject their seeds, flinging
them away from the parent plant.
Kinds of Angiosperms
• Botanists divide the angiosperms into two
subgroups, monocots and dicots.
• The monocots are
flowering plants
that produce seeds
with one seed leaf
(cotyledon).
– Most monocots also
produce flowers with
parts that are in multiples
of three and have long,
narrow leaves with
parallel veins.
Kinds of Angiosperms
• The dicots are flowering plants that produce
seeds with two seed leaves, dicotyledons.
– Most dicots also
produce flowers
with parts in
multiples of two,
four, or five and
have leaves with
branching veins.
Familiar Families of Angiosperms
Subgroup
Monocots
Family
Examples
Iridaceae
(Iris)
Irises, gladiolus, crocus
Liliaceae
(Lily)
Daylilies, tulips,
asparagus, aloe vera
(class
Monocotyledonae)
Poaceae
(Grass)
Wheat, corn, rice,
lawn grasses
Dicots
Asteraceae
(Aster)
Daisies, sunflowers,
lettuce, ragweed
Brassicaceae
(Mustard)
Broccoli, cauliflower,
turnips, cabbage
Fabaceae
(Legume)
Beans, clovers, peas,
peanuts, soybeans
Rosaceae
(Rose)
Roses, apples, peaches,
pears, plums
Solanaceae
(Nightshade)
Potatoes, tomatoes,
peppers, petunias
(class Dicotyledonae)
Plants as Food
• Humans depend on plants in many ways.
• Plants store the extra nutrients they make or
absorb in their bodies.
• Plant parts contain organic nutrients
(carbohydrates, fats, and proteins) and
minerals (calcium, magnesium, and iron).
• All types of plant parts – roots,
stems, leaves, flowers, fruits,
and seeds – are eaten as food.
Fruits and Vegetables
• To a botanist, a fruit
is the part of a plant
that contains seeds.
• A vegetative part is any
nonreproductive part of a plant.
• The foods that you think
of as fruits (such as apples,
bananas, and melons) are also
fruits in the botanical sense.
• Vegetables that contain seeds are
fruits in the botanical sense such
as cucumbers or tomatoes.
• Fruits and vegetables provide
dietary fiber and are important
sources of essential vitamins and
minerals.
Root Crops
• Potatoes are an important food
staple in many parts of the world.
– Rich in calories and easy
to grow, potatoes are an ideal
crop for a small farm.
– They are classified as root crops
because they grow underground.
– Potatoes are actually tubers, modified
underground stems that store starch.
• Yams, an essential food crop in many tropical
parts of the world, are roots.
• Sweet Potatoes, carrots, radishes, turnips,
beets, and cassava are important root crops.
– These vegetables are enlarged roots that store
starch.
Legumes
• Many members of the pea family, which are called
legumes, produce protein-rich seeds in long pods.
– About 45% of a soybean,
the most important legume
grown for food, is protein.
• Soybeans are often cooked and
pressed into cakes called tofu.
• Peas, peanuts, and the many different types of
beans are the seeds of legumes.
• Alfalfa, which is fed to livestock, is another
important legume.
– Like many legumes, alfalfa has nitrogen-fixing
bacteria, which add nitrogen compounds to the soil, in
its roots.
• Alfalfa is also grown to enrich the soil.
• Student handout ends at this point;
however, the following slides will be
presented during a plant lab.
Cereals
• Cereals are grasses that are grown as food
for humans and livestock.
• Cereal grasses produce large numbers of type
of edible, dry fruit called a grain.
• A grain contains a single seed with a large
supply of endosperm.
• Each grain develops
from a flower.
• The flowers of cereal
grasses form in tightly
packed clusters of many
individual flowers.
Cereals
• A grain is covered by a dry,
papery husk called the bran,
which includes the wall of the
ovary and the seed coat.
• Cereal grains are rich in
carbohydrates and also contain
protein, vitamins, and dietary
fiber.
• More than 70% of the world’s
cultivated farmland is used for
growing cereal grains.
• More than half of the calories
that humans consume come
from just three cereal grasses:
wheat, corn, and rice.
Wheat
• For more than 1/3 of the world’s population, wheat is
the primary source of food.
• The endosperm of wheat grains, which is high in
carbohydrates, is
commonly ground into
white flour and used to
make breads and pasta.
• Vitamin-rich wheat germ
consists of the embryos
of wheat grains.
• Whole-wheat flour consists
of the endosperm plus
the germ and bran layers.
Wheat
• Wheat grains are not always ground into flour.
– In the Middle East, wheat grains are often boiled
or soaked, dried and then pounded until they
crack.
• Most wheat is grown in temperate regions that
have fertile soil and
moderate rainfall.
– One of the world’s best
wheat-growing areas is
the Great Plains region
of the US and Canada.
Corn
• Corn is the most widely cultivated crop in the US.
• American colonists of the 1600s and 1700s first
learned how to grow corn from Native Americans.
• In the southeastern US,
corn was more widely
grown than wheat, which
does not grow as well
in hot climates.
• Foods that are made from
corn include corn bread,
corn pone, hominy, and grits.
Corn
• About 70% of the corn crop harvested in the
US is consumed by livestock.
• Other uses for corn include the production of
corn syrup, margarine, corn oil, cornstarch,
and fuel-grade ethanol.
• Most of the corn grown
in the US today comes
from a region known
as the Corn Belt,
which includes Iowa,
Nebraska, Minnesota, Illinois, and Indiana.
Rice
• For more than half of the people in the world, rice
is the main part of every meal.
• Although it is low in protein, rice is an excellent
source of energy rich carbohydrates.
• While brown rice still has its vitamin-rich bran
layers, white rice has been processed to remove
the bran layers.
– This processing helps to
prevent spoilage in stored rice.
– In societies where people eat
mainly rice, vitamin-rich sauces
such as soy sauce are often
added to white rice to make
meals more nutritious.
Rice
• The white rice you buy at a
grocery store is enriched with
added vitamins.
• Rice is often added to
processed foods such as
breakfast cereal, soup, baby
food, and flour.
• In the US, rice is grown in
central California, in the
Southeast, and along the Gulf
Coast in fields.
Nonfood Uses of Plants
• Wood
– After food, wood is the single most valuable resource
obtained from plants.
• Many products such as furniture, buildings,
boats, cabinets, and violins are made from wood.
– The wood from trees that have been cut down and
sawed into boards, is called lumber.
• Nearly 75% of the lumber cut in the
US is used for building construction.
• The rest is used to make products
that contain wood, or it is ground
and moistened to make wood pulp.
• Wood pulp is made into paper, rayon,
and many other products.
– For more than a quarter of the world’s people, wood is
still the main source of fuel for heating and cooking.
Nonfood Uses of Plants
• Medicines
– By studying the plants traditionally used to treat
human ailments, researchers have developed many
“modern” medicines.
Name
Source
Action
Caffeine
Tea leaves
Acts as a stimulant
Codeine
Poppy fruits
Relieves pain
Cortisone
Yam tubers
Relieves symptoms of allergies
Digitalis
Foxglove leaves
Stabilizes irregular heartbeats and
treats cardiac disorders
Ephedrine Ephedra stems
Acts as a decongestant
Salix
Bark of willow trees Relieves aches and pains (aspirin)
Taxol
Yew tree bark
Reduces the size of cancerous tumors
Nonfood Uses of Plants
• Fibers
– Fibers are strands of cellulose, which is
a component of the cell walls of plants.
– In plants, fibers help provide support for plant
body.
– The strength and flexibility of plant fibers make
them ideal materials for making paper, cloth, and
rope.
• Most of the fibers used to make paper come from wood.
– Paper-making fibers are also obtained from many
other plants, including cotton, flax, rice, bamboo,
and papyrus.
Nonfood Uses of Plants
– For centuries, people have made
clothing with cloth made of cotton,
the world’s most important plant fiber.
• White fibers fill up the inside of a
cotton boll, the fruit of the cotton plant.
• Cotton thread is spun from the fine white
fibers, which grow on cotton seeds.
– The stems of flax yield softer, more
durable fibers that are used to make linen.
– More than 30% of the world’s clothing is
now made of synthetic fibers, but natural
plant fibers are still prized for their
durability and comfort.
– Sturdy fibers of hemp and sisal
plants are used to make rope.