Summary BOT161 - Notes on flowers

Flowers
Embryo sac and Pollen grains • One sperm fuses with egg - diploid
• Plants have haploid (gametophyte) zygote (divides via mitosis to
and diploid (sporophyte)phases in produce embryo)
life cycle • One fuses with other nuclei in
• Angiosperms embryo sac (polar nuclei) to form
§ Gametophyte in sperate triploid endosperm mother cell
plants (divides via mitosis to produce
§ Male - pollen grain (sperm) endosperm)
§ Female - embryo sac (egg) • Ie double fer@liza@on - unique to
• A>er meiosis - separate angiosperms
mul@cellular individuals (spores • Endosperm
NOT gametes) § storage @ssue in early
• Spores grow - haploid plants matura@on
(gametophytes) - produce sex cells § in rice, maize, wheat and
(gametes) via mitosis barley
• Pollen grain - 2 sperm cells / inflorescences
embryo sac - 1 egg • sunflowers, daises,
§ Depend on diploid parent chrysanthemums
for nutri@on
§ Pollen - during original
development and growth of
pollen tube
§ Embryo sac - en@re
existence
• Embryo sac - in ovule
How pollen is transported
• Pollina@ng agent/vector - moves
pollen to embryo sac
§ Bio@c - insects, birds, Reproduc@ve features
mammals (rodents, shrews, • all stamens together - androecium
bats) • all carpels together - gynoecium
§ Abio@c - wind, water
• Pollina@on - transfer of pollen from
anther to s@gma
• Fer@liza@on - fusion of male and
female gametes
Hermaphrodi@c plants
• Flowers have male (sperm-
producing via pollen) and female
func@on (egg producing via
embryonic sac)
• Do not inbreed
Sperm in reproduc@on
• Both sperm cells used in sexual
reproduc@on