Bellringer-March 17, 2014

1) How do flowers reproduce?2) Do flowers have separate male and female

organs? 3) How do monocot and eudicot flowers differ?

Flowers/ReproductionAquaponics

Flower• Sexual reproductive structure

• Produces egg and sperm

• Fertilization takes place inside the flower

The flower: the defining structure of angiosperms

Reproductive structure: pollen transfer; specialized shoot with modified leaves

Sepals: enclose flower before it opens

Petals: attract pollinators Stamens: male sex organs;

anther (produces pollen), filament

Carpels (Pistal): female sex organs; stigma, style, ovary, ovules

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

• Flowers/fruits can be carried by wind, water, or animals to new locations, enhancing seed dispersal

Figure 30.9a–c

Wings enable maple fruits to be easily carried by the wind.

(a)

Seeds within berries and other edible fruits are often dispersed in animal feces.

(b)

The barbs of cockleburs facilitate seed dispersal by allowing the fruits to “hitchhike” on animals.

(c)

Pollination

Pollination: Transfer of mature pollen grains from the anther to the stigma

• 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

Fruits• Form when ovary with ovules

(eggs) ripens• May be dry and hardened (nuts)• May be enlarged and fleshy

(berries, apples, tomatoes) …TASTY!!!

• Used to help disperse seeds

2 groups of Angiosperms (flowers) Monocots: 1 embryonic seed leaf called cotyledon

(lilies, palms, grasses, grain crops); parallel venation; 3 petals

Eudicots (formerly Dicots): 2 embryonic seed leaves (roses, peas, sunflowers, oaks, maples); netlike venation; 4-5 petals

Vascular tissue refinement: vessel elements/fiber cells