reproduction in flowering plants emphasis on pollinators mrs. zemcik living environment expanded by...
Post on 19-Dec-2015
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Reproduction in Flowering Plants
Emphasis on Pollinators
Mrs. Zemcik
Living Environment
Expanded by
Joe Naumann, UMSL
Flower• Sexual reproductive structure
• Produces egg and sperm
• Fertilization takes place inside the flower
Pistil*Stigma –top of the pistil,Sticky surface for pollen to
stick to*Style – connects the stigma
to the ovary*Ovary –contains ovules ( eggs)
Stamen*Anther – produces sperm
nuclei by meiosis. Sperm nuclei are enclosed by pollen grains.
*Filament – holds the anther up
Female reproductive organ
Male reproductive organ
Pollination
• Transfer of mature pollen grains from the anther to the stigma
-wind
-insects
-birds & other animals
Important (endangered?) Pollinators• Bees• Butterflies• Moths• Wasps• Bombyliid flies• syrphid flies • Beetles• Midges• Thrips• Ants
• Green bottle flies• Bactrocera fruit flies• Bats• Birds
– Hummingbirds– Honeyeaters– Sunbirds
• monkeys, lemurs, possums, rodents and lizards
Pollinator population declines and conservation
• In 1999 the Convention on Biological Diversity issued the São Paulo Declaration on Pollinators, recognizing the critical role that these species play in supporting and maintaining terrestrial productivity as well as the survival challenges they face due to anthropogenic change. Today pollinators are considered to be in a state of decline; some species, such as Franklin’s bumble bee (Bombus franklini) have been red-listed and are in danger of extinction.
Serious Problem
• Declines in the health and population of pollinators pose what could be a significant threat to the integrity of biodiversity, to global food webs, and to human health. At least 80% of our world's crop species require pollination to set seed. An estimated one out of every three bites of food comes to us through the work of animal pollinators.
• When a pollen grain lands on the stigma, it germinates and a pollen tube grows down through the style to an ovule (egg)
Fertilization• The sperm travels through the pollen tube to the
ovule. The sperm & egg fuse forming the zygote (fertilized egg) –this grows into the plant embryo (cells grow by mitosis)
*Self pollination –pollen from same flower
*Cross pollination – pollen from a different flower - more variation
• The ovary and zygote (fertilized ovule) develop and ripen.
*The ovule forms the seed and the ovary forms the fruit.
• A fruit is a ripened ovary
The plant embryo uses food stored in the cotyledon of the seed until it develops
leaves for photosynthesis
micropyle –opening in ovule where pollen tube attached, sperm entered
hilum –scar where ovule attached to ovary
radicle –embryonic root
Seedling
Epicotyl – grows above the cotyledons and gives rise to the leaves.
Hypocotyl –below the point of attachment of the cotyledon, develops into the stem.
Parts of a seed
• Dicot
• Monocot
Seed coat
Epicotyl
Cotyledons
Hypocotyl
Seed coatEndosperm
Epicotyl
Hypocotyl
RadicleCotyledon