Plants
Plant Characteristics and
Special Functions
Overview of Plants
 all shapes and sizes
 all types of environments
Common Characteristics of Plants
About 260,000 species of plants live on Earth today.
All plants:
1.
2.
3.
4.
Are multicellular
Have a nucleus surrounded by a cell wall.
Are producers – capture light from the Sun.
Have life cycles divided into two stages (generations).
Special Functions
Below ground: roots
Absorb water and nutrients from soil.
Transport materials to leaves through the stem.
Above ground: stems and leaves = shoot system
Leaves use materials + CO2 to make sugars and carbohydrates through
photosynthesis.
Transporting Materials
Materials move through a vascular system.
Stems transport the materials from one part of the plant to
another.
The vascular tissues are bundled together from the root to the
leaves; look like tubes.
Transporting Materials - Tissue
Xylem: carries water and dissolved nutrients up from roots.
Phloem: transports energy-rich materials, such as sugar, down
from leaves.
Both are long, hollow tubes that contain fibers to support the
body of the plant.
Xylem is a little larger.
Transporting Materials - Tissue
Making Sugars - Photosynthesis
Plants make sure through
photosynthesis.
What is the formula?
Co2 + H2O + sunlight  oxygen + glucose
(C6H12O6)
Where does it take place?
In the chloroplasts, which contain chlorophyll
Inside of the Leaf
Upper layer is filled with
chloroplasts.
Vascular tissue is located toward
the center.
Stomata, or tiny openings, are
located on the bottom of the leaf –
gas exchange occurs here (CO2
comes in, O2 goes out).
Controlling Gas Exchange
Stomata can open and close to let CO2 and oxygen in and out.
Water is able to evaporate from open stomata  transpiration.
Sunlight and wind cause transpiration.
Water Loss
Plants have a waxy cuticle, or protective layer, to prevent too
much water from evaporating.
Stomata can open and close to prevent this, also.
Adapting to Environment - Cactus
Special adaptation – no leaves – uses
spines instead.
Photosynthesis occurs in the stem, where
the cactus is able to hold more nutrients
without the threat of transpiration.
Plant Growth
Plants grow as long as they live.
They get bigger when cells at the tips of their roots and stems
divide and multiply more quickly than other cells.
Only stems grow leaves – leaves grow from buds.
The Stem – Three Functions
Holds the vascular system
Provide support and plant structure
Store sugars produced by photosynthesis
Soft Stems
Wildflowers, garden flowers, and vegetables
Survive by using the carbs stored in its roots to grow new, soft,
green stems and leaves in warmer weather.
Woody Stems
Trees and shrubs
Tough, thick stems that do not die each
year.
Keep growing longer/thicker
Tough xylem layer  wood
Plants
Mosses and Ferns
Plant Life
Begin to appear about 475 million years ago.
Probably looked like green algae found in shallow
ponds today.
The First Plants
Had to adapt from aquatic to land organisms.
They had to be able to get all of their nutrients,
water, and sunlight in a new environment.
Ancestors of mosses and ferns – evolved from
algae.
Mosses and Ferns
Mosses are simpler
Liverworts and hornworts are closely related
Ferns appeared later
The First Plants
Had to adapt from aquatic to land organisms.
Ancestors of mosses and ferns – evolved from
algae.
Mosses are nonvascular.
Moss cells have a cell wall and storage areas
(central vacuoles).
Do not grow large, but they have structures that
act like roots, stems, and leaves.
Nonvascular: no vascular tissues (xylem and
phloem); the nutrients just move from cell to cell.
Mosses are nonvascular.
Moss Reproductive Cycle
first part – moss grows and maintains itself.
Second part – spore producing stage; there must
be enough water.
Spore: single reproductive cell that has a hard covering;
small and transported through the air.
Plants that grow from spores – first generation.
Moss Reproductive Cycle
When you see a clump of moss, it contains both
male and female reproductive structures that
produce reproductive cells.
Male cells need water in order to move to and
fuse with a female cell.
Moss Reproductive Cycle
Fertilized eggs grow into a small stalk wit a
capsule on the end – the second generation.
Meiosis produces thousands of spores inside the
capsule.
When they are released, the cycle starts over.
Moss Reproductive Cycle
Ferns are vascular plants.
Ferns, horsetails, and club mosses were the first
vascular plants on Earth.
Can grow much larger because they have support.
Roots can branch out more underground, stems go
grow taller and branch out to smaller stems, and
leaves can grow – more sugars (more
photosynthesis).
Fern Reproduction
Leaves (fronds) contain
clusters of spores on the back.
Spores grow into tiny
structures that are close to the
ground; these contain the male
and female cells.
First generation
Fern Reproduction
When there is enough water, male cells move to
fuse with female cells.
The fertilized egg forms a plant with new fronds –
the second generation.
As plant grows, female structures die away and
clusters of spores reproduce.
Fern Reproduction
Moss/Fern– Asexual Reproduction
A small piece can separate and grow into a new
plant.
Allows plants to spread more easily.
But, provides less diversity.
Plants
Seeds and Pollen
Seeds
Seed: young plant enclosed in a protective coat.
The seed contains all of its nutrients inside of the
coat – allowing it to survive harsh conditions.
Seeds
Fertilization brings about the next generation of
plant, beginning with the embryo: the immature
form of an organism that has potential to grow.
Seeds
The seed will begin to grow when conditions are
just right.
Germination: beginning of growth of a new plant
from a spore/seed.
Takes in water and uses nutrients inside seed to
grow.
Seeds vs. Spores.
Seeds
Both
Spores
- Multicellular embryo
- Protective coat to
allow survival in harsh
conditions
- Made of single cell
- Contains nutrients
- Contains parent’s
DNA
- No nutrients
Seeds
Seed plants are more commonly found for a few
reasons.
Carried by wind, water, and animals.
Water not needed for male cells to fertilize
female cells.
Pine Trees
Pollen: small multicellular structure that holds a
sperm cell.
When a pollen grain attaches to the part of a
plant that contains an egg, pollination occurs.
Pine Trees – Life cycle
1. meiosis occurs in the pine
cones, producing male and
female cells; each tree has M
and F cones.
2. Male cones: pollen;
female cones: egg cells are
found in cone scales.
Pine Trees – Life cycle
3. female cone produces sticky substance and the
pollen lands on it. Pollen tubes grow to allow male
cells to fuse with female cells.
4. fertilized egg becomes an embryo in a seed
which is released from the pinecone.
Pine Trees – Life cycle
Meiosis and fertilizaiton
Pollen grain + egg cell = first generation
Seed + trees that grow = second generation
Gymnosperms
Gymnosperm: seeded plants
Have been on Earth for 250+ million years.
They produce seeds that are not in fruit.
4 types
Conifers
Cone-bearing trees
Pine, fir, spruce,
redwood, etc.
Cold climates
needle-shaped leaves
Others
Cycads: palm-like plants; tropical
Gnetophytes: tropical
Ginkgoes
Plants
Angiosperms
Angiosperms
Angiosperm: flowering plants
Flowers and fruit
Most plants on Earth today are angiosperms.
Angiosperm Life Cycle
Male cells found in pollen.
Female cells develop into embryos in a seed.
Separate structures for male and female structures.
The M and F cells are contained in a flower.
Angiosperm Life Cycle
Flower: reproductive structure
Egg cells develop in ovary.
Once eggs are fertilized, the ovary grows into a
fruit.
Cherry Tree Life Cycle
1. flower is reproductive structure; anthers are
male parts and pistils are female parts. Meiosis
occurs in both parts.
2. pollen is released and caught on the pistil;
pollen tube grows and an egg cell matures.
Cherry Tree Life Cycle
Cherry Tree Life Cycle
3. fertilization occurs and an embryo forms with a
seed coat; ovary  fruit.
4. fruit may fall or be eaten; if seed lands in a
suitable spot, germination occurs.
Angiosperms Asexually Reproduce
new shoots can grow out of a parent plant and
grow a new plant.
Strawberries do this.
Helps when environmental conditions are not
suitable.
Flowers
Sepals: leafy structures
that enclose flower before
blooming; form base for
flower.
Petals: leafy structures
arranged in a circle around
the pistil; colorful to attract
plant pollination.
Flowers
Stamen: male rep.
part; filament-stalk and
anthers- produces sperm
cells.
Pistil: female rep. part;
ovary-at base, contains
egg; stigma- where
pollen attaches.
Fruit
Fruit = ripened plant ovary.
Some have many seeds (apple), others that just
one (cherry).
Some are fleshy (corn), others are dry (peanuts).
Animals and Angiosperms
Plants are food for animals; animals move pollen
from flower to flower and seeds place to place.
Animals that move pollen are pollinators.
Advantage of animal pollination: pollen goes to
wear it is needed most.