Classification of
Plants
A plant can be divided into 3 parts
leaf
21.3 Roots and Stems
TEKS 4B, 5B, 10B, 10C
Stems support plants, transport materials, and provide
storage.
• Stems have many functions.
– support leaves and flowers
– house most of the vascular system
– store water
Baobab trees
Cactus
21.3 Roots and Stems
TEKS 4B, 5B, 10B, 10C
Stems support plants, transport materials, and provide
storage.
• Stems have many functions.
– support leaves and flowers
– house most of the vascular system
– store water
– grow underground for storage
Ginger rhizomes
Potato tubers
• Rhizomes
– underground,
horizontal roots with
that sprout new
plants
– may also be referred
to as creeping
rootstalks, or
rootstocks
– Example: Ginger,
horseradish
Strawberry
• Stoloniferous
– Sends out above
ground roots to
sprout a new plant
– Example:
strawberries
21.3 Roots and Stems
TEKS 4B, 5B, 10B, 10C
• Primary growth increases a plant’s length.
• Secondary growth increases a plant’s width.
21.3 Roots and Stems
TEKS 4B, 5B, 10B, 10C
• Some stems are herbaceous and conduct photosynthesis.
21.3 Roots and Stems
• Some stems can be woody,
and form protective bark.
TEKS 4B, 5B, 10B, 10C
20.3 Diversity of Flowering Plants
TEKS 7B, 7D, 8B
Flowering plants are also categorized by stem type and
lifespan.
• Stem type can be woody or herbaceous.
– Wood is a fibrous
material made up of
dead cells.
– Wood has high
concentrations of
lignin and cellulose.
– Woody stems
are rigid
Oak
20.3 Diversity of Flowering Plants
TEKS 7B, 7D, 8B
Flowering plants are also categorized by stem type and
lifespan.
• Stem type can be woody or herbaceous.
– Wood is a fibrous
material made up of
dead cells.
– Wood has high
concentrations of
lignin and cellulose.
– Woody stems
are Rigid
– Herbaceous plants do not
produce wood. And are
photosynthetic
Iris
Types of Stems
• Tree –
– one main woody stem
– Usually over 3 meters
tall
• Shrub
– Multiple woody stems
– Normally under 3
meters tall
Types of Stems
• Vine
– No supporting stem
– Woody or non-woody
• Herbaceous
– Non-woody
– Grasses, bamboo
21.3 Roots and Stems
TEKS 4B, 5B, 10B, 10C
Roots anchor plants and absorb mineral nutrients from
soil.
• Roots provide many
functions.
– support the plant
– absorb, transport,
and store nutrients
– root hairs help
absorption
21.3 Roots and Stems
TEKS 4B, 5B, 10B, 10C
• There are several parts of a root.
– root cap covers the tip
root cap
21.3 Roots and Stems
TEKS 4B, 5B, 10B, 10C
• There are several parts of a root.
– root cap covers the tip
– apical meristem is an area
of growth
apical meristem
Specialized tissue in plants
1. Meristematic Tissue- only area of plant
that will produce more cells by mitosis,
the cells are undifferentiated at first.
-
Apical meristem- unspecialized tissue
growing at the tips of roots, branches
21.3 Roots and Stems
• There are several parts of a root.
– root cap covers the tip
– apical meristem is an area
of growth
– vascular cylinder contains
xylem and phloem
vascular cylinder
TEKS 4B, 5B, 10B, 10C
21.3 Roots and Stems
TEKS 4B, 5B, 10B, 10C
• There are two main types of roots.
– Fibrous root systems have fine branches.
– Taproot systems have one main root.
Fibrous root
Taproot
Plants with fibrous roots
Grass
Violet
Types of Roots
• Taproots
– Single main root with
secondary hair-like
roots extending
– Makes it harder to pull
them from the ground
– Examples include
carrots, dandelions,
beets and radishes
Plants with taproots
Carrots
Beet
Types of Roots
• Tuberous root
– Excess starch storage
in the roots
– Example: potato
Types of Roots
• Bulb
– Actually an
underground STEM
for storage
– Example: onions
21.4 Leaves
TEKS 4B, 5B, 10B, 10C
Most leaves share some similar structures.
• The blade is usually broad and
flat.
– collects sunlight for
photosynthesis
– connects to the stem by a
petiole
blade
petiole
Upper epidermis
Palisade mesophyll
chloroplast
Lower epidermis
Phloem
Xylem
Spongy
mesophyll
guard
cells
cuticle
stomata
21.4 Leaves
TEKS 4B, 5B, 10B, 10C
• Mesophyll is between the leaf’s dermal tissue layers.
cuticle
upper
epidermis
palisade
mesophyll
spongy
mesophyll
lower
epidermis
21.4 Leaves
TEKS 4B, 5B, 10B, 10C
Most leaves are specialized systems for photosynthesis.
• There are two types of mesophyll cells.
– both types contain chloroplasts
– palisade mesophyll absorbs sunlight
– spongy mesophyll connects to stomata
cuticle
upper
epidermis
palisade
mesophyll
xylem
spongy
mesophyll
phloem
lower
epidermis
stomata
21.4 Leaves
TEKS 4B, 5B, 10B, 10C
• Guard cells surround each stoma.
– Stomata open and close when guard cells change
shape.
– When stomata are open, water evaporates and gas
exchanges.
– Stomata close at night and when plant loses too much
water.
guard cells
stoma
21.4 Leaves
TEKS 4B, 5B, 10B, 10C
• Leaves may be simple, compound, or double compound.
Simple leaf
Compound leaf
Double compound leaf
21.4 Leaves
TEKS 4B, 5B, 10B, 10C
• Leaf margins may be toothed, entire, or lobed.
Toothed margin
Entire margin
Lobed margin
21.4 Leaves
• Leaves have many adaptations.
– for extreme temperatures,
ex: pine needles
TEKS 4B, 5B, 10B, 10C
21.4 Leaves
• Leaves have many adaptations.
– for extreme temperatures,
ex: pine needles
– for water loss,
ex: cactus spines
TEKS 4B, 5B, 10B, 10C
21.4 Leaves
• Leaves have many adaptations.
– for extreme temperatures,
ex: pine needles
– for water loss,
ex: cactus spines
– for aquatic environments,
ex: water lily
TEKS 4B, 5B, 10B, 10C
21.4 Leaves
• Leaves have many adaptations.
– for extreme temperatures,
ex: pine needles
– for water loss,
ex: cactus spines
– for aquatic environments,
ex: water lily
– for getting food,
ex: Venus’ flytrap
TEKS 4B, 5B, 10B, 10C
21.4 Leaves
TEKS 4B, 5B, 10B, 10C
• Leaf veins may be parallel or pinnate.
Parallel veins
Pinnate veins
Leaf venation
• This is the arrangement of the veins in the
leaf
– Pinnate- one main vein with secondary veins
branching from it
– Palmate- several main veins branching from a
single point and then secondary veins
branching from it
Leaf venation
• Pinnate
• Palmate
Non - flowering Plants
Bryophytes
Seedless
Vascular
Spore-producing Plants
Gymnosperms
Seed-producing
Plant Kingdom
Non-flowering
Plants
Flowering Plants
(Angiosperms)
Non - flowering Plants
Bryophytes
Seedless
Vascular
Plants
Gymnosperms
Do NOT produce flowers
Plant Kingdom
Non-flowering
Plants
Flowering Plants
(Angiosperms)
20.3 Diversity of Flowering Plants
TEKS 7B, 7D, 8B
KEY CONCEPT
The largest phylum in the plant kingdom is the
flowering plants.
20.2 Classification of Plants
TEKS 5B, 7D, 8B, 8C
• Angiosperms have seeds enclosed in some type of fruit.
– A flower is the reproductive structure of angiosperms.
– A fruit is a mature ovary of a flower.
• Angiosperms, or flowering plants, belong in phylum
Anthophyta.
20.3 Diversity of Flowering Plants
TEKS 7B, 7D, 8B
Flowering plants have unique adaptations that allow them
to dominate in today’s world.
• Flowers allow for efficient pollination.
– animals feed on pollen or nectar
– pollen is spread from plant to plant in process
Flowering Plants
(Angiosperms)
Monocotyledons
(Monocots)
Dendrobium
Orchid
Dicotyledons
(Dicots)
Clove
pink
Single
cotelydon
Two
cotelydons
Cotyledon = seed leaf
20.3 Diversity of Flowering Plants
TEKS 7B, 7D, 8B
Botanists classify flowering plants into two groups based
on seed type.
• A cotyledon is an embryonic “seed leaf.”
• Monocots have a single seed leaf.
– leaf veins usually parallel
– flower parts usually in multiples of 3
– bundles of vascular tissue scattered in stem
20.3 Diversity of Flowering Plants
• Dicots have two seed leaves.
– leaf veins usually netlike
– flower parts usually in multiples of 4 or 5
– bundles of vascular tissue in rings in stem
TEKS 7B, 7D, 8B
Single
cotelydon
Two
cotelydons
Parallel
Veins
Branched
Veins
Parallel veins
Branched veins
Single
cotelydon
Two
cotelydons
Parallel
Veins
Branched
Veins
Fibrous
Roots
Taproot
20.3 Diversity of Flowering Plants
• There are three types of plant life spans.
– Annuals mature from seed,
flower, and die in one year.
Wheat
TEKS 7B, 7D, 8B
20.3 Diversity of Flowering Plants
• There are three types of plant life spans.
– Annuals mature from seed,
flower, and die in one year.
– Biennials take two years to
compete life cycle.
Foxglove
TEKS 7B, 7D, 8B
20.3 Diversity of Flowering Plants
TEKS 7B, 7D, 8B
• There are three types of plant life spans.
– Annuals mature from seed, flower, and die in one year.
– Biennials take two years to compete life cycle.
– Perennials live more than two years.
Big bluestem
20.3 Diversity of Flowering Plants
• Fruit allows for efficient seed dispersal.
– Fruit is flower’s ripened ovary
– Surrounds and protects seed(s)
– Many forms, each function in seed dispersal
TEKS 7B, 7D, 8B
• Fruit = the developed ovary of a seed plant with its
contents and accessory parts, as the pea pod, nut,
tomato, or pineapple.
Vegetable is a general term,
not a scientific term
• Vegetable = any plant whose fruit,
seeds, roots, tubers, bulbs, stems,
leaves, or flower parts are edible, as
the tomato, bean, beet, potato, onion,
asparagus, spinach, or cauliflower.
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
KEY CONCEPT
Reproduction of flowering plants takes place within
flowers.
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
Flowers contain reproductive organs protected by
specialized leaves.
• Sepals and petals are modified leaves.
– Sepals are outermost
layer that protects
developing flower
sepal
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
– Petals can help to attract animal pollinators
petal
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
• A stamen is the male structure of the flower.
stamen
filament
anther
– anther produces pollen grains
– filament supports the anther
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
• The innermost layer of a flower is the female carpel.
stigma
carpel
style
ovary
– stigma is sticky tip
– style is tube leading from stigma to ovary
– ovary produces female gametophyte
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
Flowering plants can be pollinated by wind or animals.
• Flowering plants pollinated when pollen grains land on
stigma.
• Wind pollinated flowers have small flowers and large
amounts of pollen.
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
• Animal pollinated flowers have larger flowers and less
pollen.
– many flowering plants pollinated by animal pollinators
pollen grains
– pollination occurs as animal feeds from flower to flower
– animal pollination more efficient than wind pollination
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
Fertilization takes place within the flower.
• Male gametophytes, or pollen grains, are produced in the
anthers.
– male spores produced in
anthers by meiosis
– each spore divides by
mitosis to form two
haploid cells
– two cells form a
pollen grain
single pollen grain
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
• One female gametophyte can form in each ovule of a
flower’s ovary.
– four female spores produced in ovule by meiosis
– one spore develops into female gametophyte
– female gametophyte contains seven cells
– one cell has two nuclei, or polar nuclei
– one cell will develop into an egg
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
• Pollination occurs when a pollen grain lands on a stigma.
pollen tube
sperm
stigma
– one cell from pollen grain forms pollen tube
– other cell forms two sperm that travel down tube
20.1 Origins of Plant Life
TEKS 7A, 7E, 8C, 12A
• Pollen grains allow for reproduction without free-standing
water.
– pollen grains contain a cell
that divides to form sperm
– pollen can be carried by
wind or animals to female
structures
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
• Flowering plants go through the process of double
fertilization.
female
gametophyte
egg
sperm
polar nuclei
ovule
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
• Flowering plants go through the process of double
endosperm
fertilization.
– one sperm fertilizes
the egg
seed coat
– other sperm unites
with polar nuclei,
forming endosperm
– endosperm provides
food supply for
embryo
embryo
22.2 Reproduction in Flowering Plants TEKS 6G, 10B
• Each ovule becomes a seed.
• The surrounding ovary grows into a fruit.
22.3 Seed Dispersal and Germination
TEKS 10B
Seeds begin to grow when environmental conditions are
favorable.
• Seed dormancy is a state in which the embryo has stopped
growing.
– Dormancy may end
when conditions are
favorable.
– While dormant,
embryo can withstand
extreme conditions.
22.3 Seed Dispersal and Germination
• Germination begins the growth of an embryo into a
seedling.
– water causes seed to swell and crack coat
– embryonic root, radicle, is first to emerge
– water activates enzymes that help send sugars to
embryo
TEKS 10B
22.3 Seed Dispersal and Germination
• Germination begins the growth of an embryo into a
seedling.
– water causes seed to swell and crack coat
– embryonic root, radicle, is first to emerge
– water activates enzymes that help send sugars to
embryo
– embryonic shoot, plumule, emerges next
TEKS 10B
22.3 Seed Dispersal and Germination
• Germination begins the growth of an embryo into a
seedling.
– water causes seed to swell and crack coat
– embryonic root, radicle, is first to emerge
– water activates enzymes that help send sugars to
embryo
– embryonic shoot, plumule, emerges next
– leaves emerge last
TEKS 10B
22.3 Seed Dispersal and Germination
TEKS 10B
• Once photosynthesis begins, the plant is called a seedling.
22.1 Plant Life Cycles
TEKS 10B
Plant life cycles alternate between producing spores and
gametes.
• A two-phase life cycle is called alternation of generations.
– haploid phase
– diploid phase
– alternates between
the two
SPOROPHYTE
PHASE
fertilization
meiosis
GAMETOPHYTE
PHASE
22.1 Plant Life Cycles
TEKS 10B
• The spore-producing plant is the mature sporophyte.
– sporophyte phase is diploid
– begins with fertilized egg
– spores produced through
meiosis
• The gamete-producing plant is the
mature gametophyte.
– gametophyte
phase is haploid
– begins with spore
– gametes
produced through
mitosis
22.1 Plant Life Cycles
TEKS 10B
Life cycle phases look different among various plant
groups.
• Nonvascular plants have a dominant gametophyte phase.
– moss gametophytes look like green carpet
– moss sporophytes shoot up as stalklike structures
sporophyte (2n)
capsule
spores (1n)
gametophyte (1n)
22.1 Plant Life Cycles
TEKS 10B
• The sporophyte is the dominant phase for seedless
vascular plants.
– Fern spores form in sacs, sori, on underside of mature
sporophytes (fronds).
sporophyte (2n)
sori
22.1 Plant Life Cycles
TEKS 10B
– A fern gametophyte, or prothallus, produces sperm
and eggs.
gametophyte (1n))
rhizoid
– A zygote forms on the prothallus, growing into the
sporophyte.
22.1 Plant Life Cycles
TEKS 10B
• The sporophyte is the dominant phase for seed plants.
–
–
–
–
–
–
–
–
pine trees are typical seed plant sporophytes
female spores produced in female cones
male spores produced in male cones
male spores develop into pollen grains, the male
gametophytes
female spores develop into female gametophytes that
produce eggs
sperm from pollen travel down pollen tube toward egg
fertilized egg develops into embryo
ovule develops into protective pine seed
22.1 Plant Life Cycles
TEKS 10B
• The sporophyte is the dominant phase for seed plants.
20.1 Origins of Plant Life
TEKS 7A, 7E, 8C, 12A
• A seed is a storage device for a plant embryo.
– seed coats protect
embryos from drying
wind and sunlight
– embryo develops
when environment is
favorable
Plant Adaptations
5. Seed dispersal:
a.
decreases competition and
over-crowding
b.
can introduce the seed into a
new habitat
22.3 Seed Dispersal and Germination
TEKS 10B
• Seeds dispersed by wind can have wing- or parachutelike fruits.
Cypselae
Double samaras
Seed Dispersal
• Name: Water
• Description: Seeds or
fruits are dropped from
the plant into the rivers,
lakes or seas; seeds float
• Example: Coconut
Seed Dispersal
• Name: Animal
Description
Attach to animal fur
Example
Burrs
Ingestion followed by Apple
excretion at a different
location
Birds eat fruit and
Berries
throw away the seeds
22.3 Seed Dispersal and Germination
TEKS 10B
Animals, wind, and water can spread seeds.
• Seeds dispersed by animals can have nutritious fruits or
fruits that cling.
Seed Dispersal
• Name: Self
• Description: Forceful
ejection by various
mechanisms
• Example: Dwarf
mistletoe, Pea plant,
Squirting cucumber
22.5 Plant Hormones and Responses
TEKS 10B
KEY CONCEPT
Plant hormones guide plant growth and development.
22.5 Plant Hormones and Responses
Plant hormones regulate plant functions.
• Hormones are chemical messengers.
– produced in one part of an organism
– stimulates or suppresses activity in another part
TEKS 10B
22.5 Plant Hormones and Responses
TEKS 10B
• Gibberellins are plant hormones that produce dramatic
increases in size.
– ending seed dormancy
– rapid growth of young
seedlings
– rapid growth of some
flower stalks
22.5 Plant Hormones and Responses
• Ethylene causes the ripening of fruits.
– some fruits picked before
they are ripe
– sprayed with ethylene to
ripen when reach
destination
TEKS 10B
22.5 Plant Hormones and Responses
• Cytokinins stimulate cytokinesis.
– final stage in cell division
– produced in growing roots, seeds, and fruits
– involved in growth of side branches
TEKS 10B
22.5 Plant Hormones and Responses
• Auxins lengthen plant cells in the growing tip.
– stimulates growth of
primary stem
– controls some forms of
tropism
• A tropism is the movement
of plant in response to an
environmental stimulus.
TEKS 10B
22.5 Plant Hormones and Responses
TEKS 10B
Plants can respond to light, touch, gravity, and seasonal
changes.
• Phototropism is the
tendency of a plant to
grow toward light.
– auxins build up on
shaded side of stem
– cells on shaded
side lengthen
– causes stem to
bend toward light
22.5 Plant Hormones and Responses
TEKS 10B
• Photoperiodism is a response to the changing lengths of
day and night.
– triggers some plants to flower
– triggers fall colors/winter dormancy of deciduous trees
22.5 Plant Hormones and Responses
TEKS 10B
• Gravitropism is a plant’s response to Earth’s gravitational
pull.
– positive gravitropism is downward growth (roots)
– negative gravitropism is upward growth (shoots)
• Gravitropism- response of a plant to the
force of gravity; stems grow up, and roots
grow down, regardless of how the plant is
oriented
22.5 Plant Hormones and Responses
TEKS 10B
• Thigmotropism is a plant’s response to touchlike stimuli.
– climbing plants and vines
– plants that grow in direction of constant wind
22.5 Plant Hormones and Responses
TEKS 10B
• Some plants have rapid responses not involving growth.
– Some responses protect
plants from predators.
– Some responses allow
plants to capture food.
Rapid Response
• Rapid Response- quick reaction of plant in
response to touch that is NOT growth;
– ex: venus fly trap, mimosa
Plant Adaptations
1. Chemical defenses:
a. Some plants produce chemical compounds
that are toxic to insects that may feed on
them
Plant Adaptations
4. Carnivorous plants: Live in wet, acidic
environments with little nitrogen.
Adaptations include:
a. Ability to trap and digest insects as a
nitrogen source