Plants
What makes a plant a plant?
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•
•
•
has a cell wall
has chloroplast & chlorophyll
produce its own food
kisnot mobile
Plant Cell
Animal Cell
Vs.
So where did plants come from?
?
Plant Evolution
Early Life
• Plants evolved from algae and lived in the water
• The first plant appeared about 400 million years
ago!
Bryophytes
• Next, plants moved to land. The first plants were small and lived close
to the water because they had to absorb water from their environment.
• These plants are called Bryophytes (or non-vascular plants).
Vascular plants
• When plants developed tube-like structures that could transport water,
plants were able to live away from the water’s edge.
• These plants are called vascular plants.
What is a vascular system?
• Specialized tissue that transports water and nutrients throughout a plant.
Cross
section
of a
stem
Let’s fill in our
plant chart!
Nonvascular Plants (Bryophytes)
Characteristics:
*must live where it’s damp, moist or wet
* water moves through cell walls
* no roots, stem or leaves
* sperm move through water
Mosses
*Rhizoids - root-like
Hornwort & Liverworts
Liverworts & Hornworts
* “wort” = English for plant
Vascular Plants
Characteristics:
* can live away from water
* transport water & materials through plant
* supports their bodies
* has true roots, stems and leaves
Types:
Reproduces 1. Ferns
Without
2. Horsetails
seeds
3. Club Mosses
Reproduces
With seeds
4. Gymnosperms
5. Angiosperms
Ferns
• 400 million years old!
• Vascular tissue.
• Spores - needs moist
environment.
• Stems grow
underground.
• Leaves called fronds.
Club Moss
• Also called Ground
Pine or Princess
Pine
• Needle-like leaves
• Club Moss are
NOT mosses!!
Horsetails
• Few species today ( ONLY 30!)
• Jointed stems with branches in a circle
around each joint.
• Called “Scouring rushes” in Colonial times.
Gymnosperms
• Oldest type of seed plant
• Naked seed (not enclosed)
• Needle like or scale like leaves
• Deep growing root systems
• Cones (male & female)
Angiosperms
• Flowering Plants
• Seeds within a covering
• Flowers may have both male and female
organs.
• Two groups: monocots and dicots.
• Angiosperms are classified
into two groups based on the
number of seed cotyledons
(kaht uh leed uhns).
• Cotyledons are the leaf-like
parts of the plant embryo
inside the seed.
Monocots
• A monocot has only one cotyledon.
• There are other features typical to monocots
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–
–
–
Leaves are narrow with parallel veins
Roots are fibrous
Flower parts are in multiples of three
Stem vascular tissues are in bundles.
• Examples of monocots:
-Corn, grasses, tulips, lilies
Fun fact: Palm trees are the only monocot
trees!
Dicots
• A dicot seed has two cotyledon
• There are other features typical to dicots:
–
–
–
–
Leaves have branching pattern of veins
Dicots have a large, thick taproot- (makes it hard to uproot)
Flower parts are in multiples of four or five.
Stem vascular tissues are arranged in a ring.
• There are about four times more dicot species than there
are monocot species.
• Examples of dicots:
– All broad-leafed trees, fruit trees, tomatoes, potatoes, peas,
squash, lettuce, sunflowers, roses, violets.
Cross Section of a Leaf…
(if you were to cut a leaf and look at it from the side, you’d get this…)
Cuticle
(Waterproof coating)
• prevents excess water loss
• shiny
Epidermis
light can pass through.
• protection
•
Mesophyll
“meso” means middle
“phyll” means leaf
Palisade mesophyll
• Most photosynthesis happens here
Spongy mesophyll
• Photosynthesis occurs here too
• Air spaces allow carbon dioxide, oxygen and water vapor to flow
freely
Stomata
• “stoma” means mouth
• Opening allows carbon dioxide to enter and oxygen and water to
leaves
• Guard cells - controls opening
• Made of two slightly curved epidermal cells
• Open during day , closed at night.
Stomata Openings
100%
25%
75%
50%
15%
0%
Xylem
• carries water and minerals from roots up through plants
• helps support plant because to thick walls.
Phloem
• carries food throughout plant, both upward and
downward.
Stem Structure
• Herbaceous - soft and flexible
stems (ex: grass, corn)
• Woody - hard and stiff stems (ex:
trees, shrubs)
– Wood - old water-carrying cells (xylem)
vascular tissue
– Bark - old growth
– Cambium - produces new xylem and
phloem
Stem Function
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•
•
•
Support
holds up leaves so they are exposed to the sun
carries substances between the plant’s roots and leaves
stores glucose
Root Structure
• root cap - pushes through soil
• root hairs - increases surface area exposed to soil
• epidermis - protection
Root Function
• supports and anchors
• absorbs water and nutrients from the soil
• stores glucose in the form of starch
Types of roots
Taproot
Fibrous
Plant Reproduction
Types of Plant Reproduction
1. Asexual Reproduction- does not require the
production of sex cells (no sperm or eggs); new plant
is genetically the same as the parent.
Ex: potatoes, spider plants, strawberry plants, root,
leaf or stem cuttings.
2. Sexual Reproduction- requires the production of sex
cells (needs sperm or eggs); new plants are
genetically different from the parents.
Fertilization- sperm and egg combine to form a
new organism (called a zygote)
Plant Life Cycles
• Two Stages:
– Gametophyte- gamete- forming platns (sperm or
egg called sex cells) – haploid cells
– Sporophyte- spore-forming platns; diploid cells.
Flowers
Function
• Reproduction.
• Pollination1. Pollen falls on stigma.
2. Pollen Tube is produced that allows sperm cells to move
down to the ovary to join egg cells
3. Egg cell join with sperm cell (fertilization).
4. Ovule develops into a seed
5. The ovary develops into a fruit that encloses the seed.
The fruit helps in seed dispersal.
Structure
• Sepals - often green leaf-like; protects developing flower
• Petals - colorful leaf-like structure; attracts insects & other
animals
• Pistil - found in center of flower; female reproductive part
made up of:
– stigma - sticky tip of pistil; pollen is deposited here
– style - slender tube; connects the stigma to a hollow structure at
the base of the flower.
– Ovary- bottom of the pistil; contains eggs to be fertilized.
• Stamen - male reproductive parts that is made up of:
– filament - stem-like ; holds up anther
– anther knobs at end of stalk; pollen is produced here.
Types of flowers
• Imperfect Flower: has either male OR
female reproductive parts, but NOT both.
• Perfect Flower: has both male and female
parts.
How does
a plant get
it’s energy?
Photosynthesis!
•“photo” means light, “synthesis” means to put together
•process in which food is synthesized using light energy
•occurs in Chlorophyll (a green pigment)
•Food made is a sugar called glucose
6 CO2 + 6 H2O
Carbon
dioxide
water
Sunlight
chlorophyll
C6H12O6 + 6 O2
glucose
oxygen
Respiration
•release of stored energy in glucose
C6H12O6 + 6 O2
Glucose
oxygen
6 CO2 + 6 H2O + energy
carbon
dioxide
water