Reproduction in Flowering Plants Emphasis on Pollinators Mrs. Zemcik Living Environment Expanded by Joe Naumann, UMSL.

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

Scopa (pollen holder) of a Megachilid bee

Halictid bee, showing adhering pollen

Syrphid fly, showing

some adhering

pollen

Halictid bee

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

Seed Germination

Monocot Dicot

Hypogeous

Epigeous

Radicle

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