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Chapter 9: Flowers and Reproduction (Flower Structure and Cross…
Chapter 9: Flowers and Reproduction
Reproduction
Asexual Reprioduction
fragmentation
individual parts become self-sufficent
establish adventitious roots
progeny
genetically identical to parent
as adapted as parent
adversely effected by minor changes
rapid colonization of new site possible
isolated individuals can produce
Sexual Reproduction
Plant Life Cycle
alternation of generations
sporophyte phase
always diploid
have organs
meiosis occurs in spores
gameopyte stage
microspores
male
megaspores
female
Flower Structure
floral appendages
Sepals
lower, outermost
thickest, toughest, waxiest part of flower
used as protection
development of bud
insects
known collectively as the
calyx
petals
located above sepals
known collectively as the
corolla
sepals and petals together constitute the
perianth
attract pollinators
stamens
located above petals
known collectively as
androecium
produce pollen
filiment
anther
Tapetum
microsporoctyes
carpels
constitute the
gynoecium
located at highest level on recepticle
parts
stigma
catches pollen grains
style
elevates stigma
ovary
produces megaspores
placentae
ovules
3 more items...
ovary wall
Fertilization
plasmogamy
fusion of the protoplasts of gametes
karyogamy
fusion of the nuclei
double fertilization
occurs in angiosperms only
undergoes karyogamy with both polar nuclei
triploid endosperm nucleus
nourishes the zygote
Embryo and Seed Development
embryo proper
globular stage
heart stage
torpedo stage
radicle
epicotyl
hypocotyl
mature embryo
cotyledons
monocots
dicots
endosperm
albuminous seed
exalbuminious
testa
seed coat
suspensor
pushes embryo deep into endosperm
delicate, ephemeral
later crushed by growth
Fruit Development
pericarp
exocarp
outer layer
skin or peel
endocarp
tough innermost layer
pit
mesocarp
middle layer
flesh
entire fruit wall
mature ovary is a
fruit
Gametophytes
Microgametophyte
vegetative cell
generative cell
forms two sperm cells
pollen tube
penetrates stigma
absorbs nutrients
grows downward through style
Megagametophyte
embryo sac
central cell
two polar nuclei
three antipodal cells
egg apparatus
consists of two synergids
an egg
Flower Structure and Cross-Pollination
cross-pollination
cross pollination
pollination from different individuals
new combinations of genes
creates genetic diversity
self-pollination
pollnation from same flower
no possibility of new allels
Stamen and Style Maturation Times
self-fertiliztion prevented if mature at different times
stigma tissues unreceptive
style not elongated
exposed pollen lives briefly
desiccation in dry air
damage by UV light
no living pollen left in flower
Stigma and Pollen Incompatablity
compatability barriers
proteins produced are blocked
diploid/diploid system
Monoecious and Dioecious Species
essential organs
perfect flower
has both stamens and carpels
imperfect flower
lack stamens
incomplete flower
lack carpels
lack both essential organs
non essential organs
sepals
petals
do not produce spores
Monoecious
staminate and carpellate flowers on same plant
Examples
cattails
corn
Dioecious
produce only staminate flowers
produce only carpellate flowers
Examples
marijuana
dates
willows
papaya
life cycle
microgametophytes
megagametophytes
staminate sphorophytes
carellate sporophytes
Pollination
aminal-pollinated
distinct modifications
pigments
fragrance
nectar
size
pollen grain reaching stigma is improved
ccoevolution
flowers/insects
flower/bird
flower shape
actinomorphic
regular
radial symmetry
zygomorphic
bilateral symmetry
advantagious in pollination
wind -pollinated
distinct modifications
large feathery stigmas
zygomorphy provides no advantage
attracting pollinators is unnecessary
mutations prevent formation of petals
sepals reduced or absent
aided by growth pattern
dense populations aid pollination
widely scattered pop must rely on animals
ovary position
inferior ovary
epigynous
result if receptacle tissue grows around the ovary
superior ovary
hypogynous parts
no fusion to the ovary occurs
more common arrangement
half-inferior
intermediate, partially buried ovaries
perigynous flower parts
Inflorescences and Pollination
many flowers grouped together
Arrangements
derterminate inflorescences
limited potential for growth
apex is coverted to a flower
terminal flower opens first
indeterminate inflorescences
lowest , outermost flower opens first
Raceme
Spike
Head
Umbel
Fruit Types and Seed Dispersal
Fruits
true fruit
contains only ovarian tissue
blueberries
accessory fruit
contains any nonovarian tissue
stawberries
simple fruit
develops from a single or fused ovary
most common kind
aggregate fruit
separate carpels fuse
raspberries
multiple fruit
all individual fruits fuse
pineapple
Classification of Fruit Types
dry fruits
indehiscent fruits
developed from single carpel
caryopsis
simple, small, one seed
testa fused to fruit wall
wheat, corn, oats
Achene
seed remains distinct
fruit wall thin and papery
sunflower
Samara
one seed fruit
wing-like outgrowths
maple, alder, ash
develop from compound carpel
Nut
all but one ovule degenerate
pericarp is hard
walnut
dehiscent fruits
develop from single carpel
legume
fruit breaks open along both sides
beans, peas
follicle
fruit breaks open on only one side
columbine, milkweeds
develop from compound gynoecium
capsule
opens many ways
Iris, poppy
schizocarp
compound ovary breaks
mericaps
fleshy fruits
eaten during natural seed distribution
berry
all three layers are soft
tomato and grape
pome
endocarp is papery
apple
drupe
endocarp is hard
cherry, plum, apricot
pepo
exocarp is tough
pumpkin, squash, cantelope
hesperidium
exocarp is leathery
citrus fruits
Dispersal methods
gravity
wind
water
animals
