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Flowers and Reproduction (flower structure (carpels (three parts (style,…
Flowers and Reproduction
Fruit Types and seed dispersal
multiple fruit
figs
avaggregate fruit
rasberries
true fruit is
one ovarian tissue
the red flesh on strawberry
is receptacle not the carpel tissue
accessory fruit
pineapples
develop coalescence
multiple fruit
accessory fruit
non ovarian tissue is present
Gametophytes
microgametophyte
pollen grains
filled with giant vacuole
pollen tube
absorbs nutrients from stigma
grows downward through the style
vegetative cells
divides and forms two sperm cells
generative cell
divides and forms two sperm cells
small lens-shaped
divides and forms two sperm cells
pollen grain lands on a stigma
germinates
producing a pollen tube
penetrates into the loose open tissues of the stigma
multinucleate megametophyte
embryo sac
the seven cells
are one large central cell
two polar nuclei
three small antipodal cells
egg apparatus cons
two synergids and an egg
fertilization
syngamy of sperm and egg
plasmogamy
fusion of the protoplastof the gametes and karyogamy
angiosperms only
second sperm nucleus released from the pollen tube
migrates from the singed into the central cell
undergoes karyogamy
both polar nuclei have large endosperm nucleus
triploid containing three set of genes
Embryo and seed development
endosperm sparse or absent at maturity
the seed is exalbuminous
torpedo stage
embryo is elongate cylinder
short axis
consisting of radicle, epicotyl, hypocotyl
suspensor
pushes the embryo deep into the endosperm
two primordial cells
grow into two cotyledons
mature
embryo becomes quiescent
partially dehydrates
funiculus break leaving a scar, the hilum
endosperm is abundant is
albuminous seed
integuments
surround the nucellus
testa
expand and mature into the seed coat
The plant life cycle
sporophyte phase
herbs, trees, shrubs
sporophyte generation
always diploid
diploid adults have sex organs
produce haploid sex cells called gametes
sperm & egg called zygote
eggs
megagametes
sperm
microgametes
meiosis
results in haploid gametes
syngamy or fertilization
gametes fussing with other gametes
alteration of generations
life cycle with two generations
plant spores undergo mitosis
form a gametophyte
Inflorescence and pollination
small flower may be overlooked
don't want a lot
inflorescence
many flowers grouped together
gives a collective visual signal to pollinators
two basic arrangements occur
indeterminate inflorescence
lowest or outermost flowers open first
while flowers are open new flowers are being initiated at the apex
determinate inflorescences
limited potential growth
apex is converted into a flower
flower structure
Sepals
lowermost & outermost of floral appendages
incomplete flowers
do not have all four appendages
Petals are above sepals
on receptacle and make up a the corolla
stamen
two parts aka the filament
androecium
above petals are stamens
microspores are initially called pollen
complete flowers
have all four appendage
flowers attach receptacle
stalk is a pedicel
carpels
three parts
style
ovary
stigma
constitute the gynoecium
inside ovary are placentae
singer for placentae is ovules
ovules
small central mass of parenchyma
know as nucleus
Asexual Reproduction
adventitious buds
may grow out
fragmentation
a large spreading or vining plant grows
individual parts become self sufficient
establishing adventitious roots
middle of the plant dies
ends separate & act as individuals
willows & thistles
adventurous shoot buds form on roots
then grow into plants
Fruit Development
ovule develops into a seed
ovary mature into a fruit
mesocarp is the middle
exocarp is the outer
endocarp may be tough
Cross-pollination
pollination of a carpel by pollen from a different individual
different individual
self-pollination
pollination of a carpal by pollen from the same flower
or another flower on the same plant
no possibility of new alleles
Stigma and pollen incompatibility
compatibility barriers
chemical relations between pollen & carpels
pollen tube grows
stigma & styla test proteins
Monocious and Dioecious Species
two organs are essential organs
produce the critical important spores
if organ(s) is absent sexual reproduction is affected
flowers that lack or both essential organs
incomplete& imperfect flowers
has both it is a perfect flower
dioecious
dioecy and the species
species may have individuals
that produce only staminate flowers
produce only carpellate flowers
Monoecy
condition of having staminate flowers
located on the same plant as carpellate flowers
