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Bryophytes >450mya
Reproduction in Flowering
Plants
360 mya
Chapter 36
Fig. 27-4, p. 584
Flowering Plant Life Cycle
Lily Flower
Flower Parts
• Sepals
• cover and protect flower parts in bud
• Petals
• Can attract animal pollinators to flower
• Stamens
• produce pollen grains
Flower Parts
• Each stamen consists of
• a thin stalk (filament)
• attached to a saclike structure (anther)
• Carpel
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Female floral parts
Flower Parts
• Pistil
• a single carpel or group of fused carpels
• female reproductive unit
• carpels contain ovules (can develop into seed)
Male floral parts
Pollen grain (each
will produce two
sperm cells)
Stigma
Style
PISTIL
(consisting
of one or
more
carpels)
Anther
STAMEN
Filament
Ovary
Ovules
(each producing
one egg cell)
• Each pistil has 3 sections:
• stigma, where pollen grains land
• Style, through which pollen travels
• ovary, containing one or more ovules (produces
one egg)
Petal
Sepal
Receptacle
Peduncle
Fig. 36-1b, p. 768
Leaves
Stems
Roots
Monocots
Flowers
Seeds
embryo
cotyledon
Flower parts are in
threes or multiples
of three
Leaves have smooth
edges, often narrow,
with parallel veins
Vascular bundles
are scattered
throughout the stem
Monocots have a
fibrous root system
The seed has one
cotyledon (seed leaf)
Dicots
embryo
cotyledons
Flower parts are in
fours or fives or multiples
of four or five
Leaves are palmate
(handlike) or oval
with netlike veins
Vascular bundles
are arranged in a
ring around the stem
Dicots have a
taproot system
The seed has
two cotyledons
(seed leaves)
Fig. 17-2
Fig. 36-1a, p. 768
Pollen: The Male gametophyte
• Pollen
• Forms within pHaploid microspores go through
mitosis
• ollen sacs in anther
• Each pollen grain contains 2 cells
• 1 cell produces two sperm cells
• 1 tube cell nucleus - produces a pollen tube that
grows through the female style
Embryo Sac: Femal Gametophyte
• Within ovules that are within the ovary
Large haploid megaspores undergo mitosis to
produce 8 cells in the ovule:
• 1 egg
• 2 polar nuclei
• several other cells
• Egg and polar nuclei participate in fertilization
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Egg and
Pollen
Pollination and Fertilization
• Pollination
• transfer of pollen grains from anther to stigma
• Fertilization
• after pollination
• fusion of gametes
Pollination
•Insects are the the major pollinators
•Plants have developed many adaptations that facilitate
• Insects
pollination
Ultraviolet Markings on
Insect-Pollinated Flowers
• flowers yellow or blue
• scented
Pollination
• Birds
• flowers yellow, orange, or red
• no strong scent
Pollination
• Bats
• flowers with dusky white petals
• scented
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Pollinating Agents
Wind
• flowers make large amounts of pollen
• have smaller petals or no petals
•
•
•
•
Mimics bees!
Smell like carrion
Trap animals
Produce heat
Double Fertilization
Fertilization
• Undergo double fertilization in ovule
• 1 Sperm fuses with the Egg
• forming zygote (fertilized egg)
• zygote develops into embryo in a seed
• 1 sperm fuses with the 2 polar nuclei
• forming triploid (3N) nutritive tissue
(endosperm)
Embryonic Development
Embryo
• Develops in the seed
•
•
•
•
from proembryo
to globular embryo
to heart stage
to torpedo stage
•Embryo develops within the seed within the ovule
•Outer layer of ovule develops into a seed coat
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Mature Seed
• Contains:
• a young plant embryo
• nutritive tissue for use during germination:
endosperm or cotyledons (seed leaves)
• Tough, protective seed coat surrounds seed
Relationships among . .
.
• Ovules: have potential to develop into seeds
• Ovaries ripen and turn into fruit surrounding the
seed
• Fruits: mature, ripened ovaries!!!!!
• Seeds: enclosed within fruits
Seed and Fruit Dispersal
Explosive Dehiscence
Wind, water, animals
Germination and Growth
Germination (Seed Sprouting)
• Seed dormancy!!!!!!!
• Avoid using energy reserves while still in fruit
• Wait for favorable environmental conditions
• Internal & external factors influence
germination
• Conditions vary among species
• All need oxygen, water, sunlight (some)
• Cotyledons provide energy to sprout
Dicot
Monocot
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Plant Hormones
Darwins’ Experiments (1870s)
• Although there are many plant hormones, five have
been well-characterized:
• auxins
• gibberellins
• cytokinins
• ethylene
• abscisic acid
Plant Hormones: Auxin
• Cause Tropisms (bending of plant
• Apical Dominance
• Stimulates root development on stem cuttings
Auxins promote cell elongation
• Cause cells to elongate
• apical meristem
• explains phototropism!
• Also influences stem to grow upwards:
• Stem on side Auxin accumulates on lower side
- cells on bottom elongate and force plant up
“Gravitropism”
In roots auxin inhibits cell elongation!!!
- So what happens?
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Auxin and apical dominance
- inhibits axillary bud growth
Gibberrelins
1. Also promote cell elongation (Bolting)
2. Stimulate flowering
3. Seed germination
1. production of Gibberrelins in embryo
2. triggers synthesis of  amylase
3. digests starch in endosperm
4. provides erergy for embryo
Auxins produced by seeds promote fruit
development
2,4-D
2,4,5,-T
Cytokinins
• Promote cell division
- Fruit development
- Sprouting of buds
- Delay senescence
Ethylene
• Ripening fruits
• Regulates timing of leaf, flower, fruit drop
Abscisic Acid – stress hormone
• Stomatal closure caused by
water stress
• Maintains seed dormancy
• Heavy rain washes A.A.
out of seed and it
germinates
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Leaf abscission -
sugars
minerals
Senecence
A.A.
In response to
shortening daylengths
Separation
Chlorophyll
breaks down
layer
Protective
layer
Abscission
•Orange carotenes
•Yellow/red xanthophylls
zone
Leaf Form
Blade
Veins
• Simple
– having a single blade
Petiole
• Compound
– having a blade divided into 2 or more leaflets
Axillary bud
Stipules
Stem
Fig. 33-1, p. 716
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Leaf Form
Simple
Pinnately compound
Palmately
compound
Leaf Arrangement
• On a stem
– alternate (one leaf at each node)
– opposite (two leaves at each node)
– whorled (three or more leaves at each node)
..
California white oak
(Quercus lobata)
White ash
(Fraxinus americana)
Ohio buckeye
(Aesculus
glabra)
(a) Leaf form: simple and compound.
Venation Patterns
Parallel
Bermuda grass
(Cynodon dactylon)
(c) Venation patterns.
Pinnately
netted
Black willow
(Salix nigra)
Palmately
netted
Sweetgum
(Liquidambar
styraciflua)
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