Download flowering plants

Chapters 22-25:Plant Notes
Ferns
Conebearing
plants
Flowers; Seeds
Enclosed in Fruit
Mosses
Seeds
Water-Conducting
(Vascular) Tissue
Green
algae
ancestor
Flowering
plants
Plant Characteristics:
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photosynthetic
multicellular
eukaryotic
cell wall made of cellulose
sexual (seeds and spores) and asexual
(vegetative propagation) reproduction
• common ancestor was green algae (a protist)
• 2 Categories of Plants: Vascular and
Nonvascular (vascular tissue- is specialized
tissue for the transport of water and solutes
through a plant)
Plant Classification
• 10 Major Divisions in the Plant Kingdom
• 4 Main Divisions are:
– Bryophyta – Mosses (Nonvascular)
• 23,000 living species
• Lack vascular tissue – Need moist environment-water is
absorbed from cell to cell
• Lack true roots – have rhizoids
• Reproduce by spores
– Pterophyta – Ferns (Vascular)
• 12,000 living species
• Can inhabit drier areas
• Reproduce by spores – NO seeds
Comparison of Moss with Flowering Plant
Division of Plants Continued
– Gymnosperms : Conifers
• 550 living species
• Produce naked seeds in cones
– Angiosperms : flowering plants
• 235,000 living species
• Produce seeds
in flowers
(protected in fruit)
Two Groups:
Monocots and Dicots
Features of Seed Plants
Comparing
Comparing Features
Features of
of Seed
Seed Plants
Plants
Feature
Feature
Gymnosperms
Angiosperms
Seeds
Seeds
Bear their seeds on cones
Bear their seeds within
flowers
Reproduction
Reproduction
Can reproduce without
water; male gametophytes
are contained in pollen
grains; fertilization occurs
by pollination
Can reproduce without
water; male gametophytes
are contained in pollen
grains; fertilization occurs
by pollination
Examples
Examples
Conifers, cycads, ginkgoes,
gnetophytes
Grasses, flowering trees
and shrubs, wildflowers,
cultivated flowers
Comparison of Monocots and Dicots
Vascular Plants
• vascular plants make up over 90% of all plants
• ferns (seedless), gymnosperms (cone bearing), and
angiosperms (flowering plants)
• xylem and phloem make up vascular tissue
– xylem- tissue that carries water and minerals upward in
a plant
– phloem- tissue that carries sugars (from
photosynthesis) upward and downward in a plant
• have roots
– to absorb water, anchor the plant in the ground, protect
the plant from bacteria and fungi
– two types of roots
• taproot- enlarged primary root; grows deep to reach
water deep below the surface (carrot)
• fibrous- numerous, extensively branched roots; grow
near the surface and help prevent topsoil from being
washed away by heavy rains (grass)
Vascular Tissue
Xylem Cells
Phloem Cells
Carry water
Carry Food
More on Vascular plants…..
• have stems
– holds leaves up to sunlight and transport
water and food between roots and leaves
• have leaves
– collect light for photosynthesis
– have stomas- pores in epidermis of leaf for
carbon dioxide, water vapor, and oxygen
to be exchanged
• reproduce by seeds and spores
– ferns- have spores, no seeds (sperm and egg)
– gymnosperms- seeds in cones (pine tree)
– angiosperms- seeds in flowers (deciduous trees,
flowers, bushes)
Nonvascular Plants- Bryophytes
• Mosses, Liverworts, and Hornworts
• lack vascular tissue for long distance transport of
water and solutes
• more dependent on water, need to live in moist
environments
• lack true roots, stems, and leaves
• have rhizoids- long, thin cells that anchor them to
the ground and absorb water and minerals
• need water for sexual reproduction- sperm swim
to egg
Nonvascular Plants
Plant Life Cycle-Alternation of
Generation
• plants have two alternating phases in their lifecycle
• a diploid (2N) phase
– sporophyte (makes spores by meiosis)
• a haploid (N) phase
– gametophyte (makes gametes by mitosis)
haploid
diploid
Spores
Gametophyte
Sporophyte
mosses
Gametophyte
Sporophyte
sperm
fertilization
eggs
ferns
seed plants
Alternation of Generations in Ferns
Fern Life Cycle
Alternation of Generations in Conifers
Alternation of Generations in Angiosperms
Comparison
Flower
Structure
A Perfect
Flower
stigma
filament
anther
petal
ovary
style
sepal
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A perfect flower is one that contains both male and female reproductive
structures.
The male reproductive structures are collectively called the stamen.
The stamen consists of the filaments and anthers.
The female structures are collectively called the pistil.
The pistil consists of the ovary, style and stigma.
The sepals and the petals are called sterile structures since they are not part of
the reproductive system.
stigma
filament
anther
petal
ovary
style
sepal
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Sepals- usually green surrounding the flower and protect the flower while it is
developing
Petals- which are often brightly colored and attract insects and other
pollinators to the flower
Stamen- anther and filament
Filament- long, thin stalk that supports the anther
Anther- oval sac where pollen is made (male gametophyte)
Carpels- (pistils) produces the female gametophyte
Ovary- contains ovules (female gametophyte)
Style- stalk to carpel
Stigma- top sticky portion of the carpel, this is where pollen lands
Plant Adaptations
• Cuticle covering outside of land plants to
conserve water
• Lignin makes cell walls harder which enables
trees and woody plant to grow taller and spread
branches and leaves for catching sunlight
• Lose leaves (deciduous) to cope with drought
and become dormant
Leaf Structure
Parts of a Leaf
3.
4.
5.
6.
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3.cuticle
4. epidermis
5. mesophyll
6. vein (phloem and xylem)
7. stoma
8. guard cells
7.
8
•Mesophyll- ground tissue where photosynthesis takes place
•Guard Cell- specialized cells in the epidermis that controls the opening and
closing of the stomata
•Cuticle- waxy coating on leaf to reduce water loss
•Epidermis- outer layer of the leaf - Protection
•Xylem- cells that carry water upward from the roots
•Phloem- cells the transport sugar throughout the plant
•Stoma- pore-like openings in the underside of the leaf that allow CO2 and O2 to
diffuse in and out of the leaf
Adaptations:
• Plants regulate the
opening and
Guard cells
closing of their
stomata to balance
stoma
water loss with
rates of
photosynthesis
Stomata open
stoma Guard cells
Stomata closed
Plant Structures
• Roots
– absorb water and minerals
• root hairs-extensions of epidermis –greatly
increase surface area for absorption
– anchor plant in soil
– Store food
– Two Types of roots
– taproot-enlarged primary root
• Grow deep reaching water deep below surface
– Fibrous –numerous branched roots
• Grow near surface
Root Types
Tap Root
Fibrous Root
Plant Structures Continued
• Stems
– Hold leaves up to sunlight and transport
water and food between roots and leaves
– Produce flowers for reproduction
Cross-section of a tree trunk
Cambium = growth
Wood
Bark
Cork- contains old nonfunctioning
phloem
Xylem: Heartwood-
Cork Cambium- produces cork
contains old xylem provides
the tree with support
Phloem
wood
Vascular Cambium- produces
new xylem
Xylem: Sapwood- contains active xylem
Plant Response
• Phototropism- tendency of a plant to
grow towards a source of light
• Geotropism- response of a plant to the
force of gravity (why plants grow up)
• Photoperiodism- response of plants to
periods of light and darkness
Vegetative Propagation
Producing new plants from roots, stems or
leaves of an existing plant –(Asexual)
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Bulbs –short underground stem with thick
fleshy leaves containing stored food
Tubers – fleshy portion of an underground
stem with has buds (“eyes”)
Runners – an over ground stem that produces
new roots and upright stems at various points
Rhizomes – an under ground stem that
produces new roots and upright stems at
various points
Plant Hormones
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Chemical Messengers
molecules produced at specific locations.
Occur in low concentrations.
Cause altered processes in target cells at
other locations.
General plant hormones
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Auxins
Gibberellins
Cytokinins
Abscisic acid
Ethylene
Auxin
Auxins are produced in the
apical meristem and are
transported downward into
the rest of the plant.
Stimulate cell elongation
Other Effects of Auxin
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Apical dominance
Prevents leaf abscission
Involved in growth tropisms
Enhances fruit growth
– Auxin from the developing seeds results in
fruit growth
Apical Dominance
Fig. 28-5
Auxin associated with phototropism
Growth movement
Loosening of cell wall
Gravitropism (Geotropism)
Auxin as a weed killer
• 2,4-D – 2,4 dichlorophenoxy acetic acid
• Causes a plant to grow itself to death
• More readily absorbed by broad-leaved
plants
• Most often the “weed” of ‘Weed and Feed’
lawn fertilizers
Gibberellin
Produced in the shoot apex of leaf
buds and root system
Stimulates cell division and
elongation
Discovered in association with Foolish
disease of rice (Gibberella fujikuroi)
uninfected
infected
Effects of Gibberellins
 Produce dramatic increases in size,
particularly in stems and fruit.
 General cell elongation.
 Breaking of dormancy.
 Promotion of flowering.
 Transport is non-polar, bidirectional
producing general responses.
Fig. 28-19
Cytokinins
Function of Cytokinins
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Promotes cell division.
Morphogenesis.
Lateral bud development.
Delay of senescence.
Stomatal opening.
Rapid transport in xylem stream.
Abscisic acid
Made by the leaves
Widespread in plant body-moves
readily through the plant
Functions of abscisic acid
 General growth inhibitor – counteracts the
growth promoting effects of auxins and
gibberellins
 Causes stomatal closure.
 Readily translocated.
 Produced in response to stress.
Ethylene
H
H
\
/
C = C
/
\
H
H
Functions of ethylene
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Gaseous in form.
Rapid diffusion.
Affects adjacent individuals.
Fruit ripening.
Senescence and abscission.
Interference with auxin transport.
Initiation of stem elongation and bud
development.