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Flowers & Reproduction (Flower Structure & Cross-Pollination…
Flowers & Reproduction
Asexual Reproduction :star:
common way-fragmentation
individual parts become self-sufficient with advantageous roots
cacti, willows, aspens
Sexual Reproduction :star:
Life Cycle
sporophytes=diploid
spores=haploid
undergo mitosis= gametophyte
micro=male
mega=female
Flower Structure
flower stalk=pedicel
receptacle=axis of attachment
complete flower=petals, stamens, carpels, and sepals
sepals=modified leaves=protection=together are a calyx
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petals=make up corolla=attract pollinators
stamens=filament & stalk=produce pollen
carpels=stigma, style, ovary, nucellus
Gametophytes :check:
microgametophytes
consists of vegetative cell & two sperm cells
pollen grain into pollen tube
megagametophyte
two, four, then eight haploid nuclei in a cell
Fertilization :tada:
double fertilization=both sperm nuclei undergo fusion
endosperm nourishes the zygote
eating it when eating wheat, corn, rice, or oats
Embryo & Seed Development
zygote undergoes nuclear & cellular divisions
suspensor pushes embryo into endosperm
radicle=embryonic root
epicotyl=embryonic stem
hypocotyl=root/shoot junction
Fruit Development
ovary matures into fruit
exocarp=outer layer (peel)
mesocarp=flashy middle
endocarp=tough or thin inner layer
pericarp=entire fruit wall
Flower Structure & Cross-Pollination
Cross-Pollination
pollination of a carpel by pollen from a different individual
new combinations of genes
self-pollination=pollination of a carpel by pollen from same flower or another flower on the same plant
has about same result as asexual reproduction
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Stamen & Style Maturation Times
self fertilization only occurs if anthers & stigmas mature at same time
Stigma & Pollen Incompatibility :no_entry:
many crop species
compatibility barriers=chemical reactions btween pollen & carpels=no pollen growth
diploid/diploid system
Monoecious & Dioecious
essential organs=stamens & carpels
lacking either or both=imperfect flower
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perfect flower=both stamens & carpels
nonessential organs=sepals & petals
dioecious=staminate flowers & carpellate flowers produced
ensures cross-pollination
monoecious=staminate flowers on the same plant as carpellate flowers
Animal-Pollinated Flowers
mutations=pigments, fragrances, & sugar-rich secretions
has higher probability of pollen reaching stigma vs wind pollen
evolution created their different shapes and sizes
Wind-Pollinated Flowers :
don't need fragrance, pigment, or sugar secretions for pollinators
flowers tend to be tiny
huge numbers of grains are produced
conifers, grasses, oaks
Ovary Position
must be protected from pollinators
long styles and stamen filaments for protection
ovaries are deep within flower
Inflorescences & Pollination
inflorescence=many flowers grouped together
give pollinators visual cues
plant can be available longer for pollinators
determinate inflorescences=limited potential for growth
indeterminate inflorescences=some flowers open first then the innermost open
Fruit Types & Seed Dispersal
fruits result in protection & distribution of seeds
seed dispersal=gravity, wind, water, & animals
True Fruits & Accessory Fruits
true fruit=fruits containing only ovarian tissue
accessory fruit=if any nonovarian tissue is present
false fruit
Classification of Fruit Types
dry=not typically eaten by natural seed-distributing animals
fleshy=eaten during natural seed distribution process
must be consumed but not damaged
