Angiosperms

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Angiosperms

Earth’s dominant plants

Angiosperm Characteristics

Vascular

Dominant sporophyte generation

Flowering plants

Xylem

– vessel elements

Double fertilization

Seeds are covered in a fruit

Phloem

– sieve tube elements

2 Largest Classes

Monocots

Grasses, corn, palms

Mainly herbaceous

Parallel veins in leaves

Flower parts

– multiples of

3

Seed

– 1 cotyledon, endosperm

Eudicots

Roses, sunflowers, maples

Herbaceous or woody

Branched veins

Flowers

– multiples of 4 or

5

Seed

– 2 cotyledons

Flowers

Reproductive part of angiosperms

4 parts: sepals, petals, stamens, carpels

Complete vs. Incomplete flowers

Perfect vs. Imperfect flowers

Reproduction

Pollination

Wind

Water

Pollinators

Double Fertilization

Germination

What happens in the anther?

Pollen sac contains many microsporocytes

Meiosis

4 haploid microspores

Each microspore

 gametophyte pollen grain (immature male

Each pollen grain contains 2 cells:

Tube cell

Generative cell

Anther splits

– sheds pollen

What happens in the pistil?

Each ovule in ovary contains megasporocyte

Meiosis

4 haploid megaspores

3 megaspores disintegrate

Remaining megaspore divides

(aka embryo sac) gametophyte

Gametophyte contains 7 cells w/ 8 nuclei

Egg cell contains 1 nucleus

Large center cell contains 2 polar nuclei

Double Fertilization

Pollen lands on sticky stigma

Tube cell forms pollen tube through style into ovary

Generative cell divides

2 sperm cells

Double Fertilization

1 sperm fertilizes egg

 zygote

 embryo

1 sperm fuses with both polar nuclei

 endosperm

3

n

cell

Seed and Fruit Formation

Ovule develops into seed

Ovary wall enlarges

Ripens into fruit

Flower parts fall off

Fruits:

Protect seeds from dessication

Aid in dispersal

Success of Flowering Plants

Seeds an advantage over spores

Cross-pollination

– increases variation

Animals disperse pollen and fruit farther than wind

Efficient xylem

Vessel elements

Broad leaves

 efficient photosynthesis

Abscission

Reduces water loss

Adaptability of sporophyte generation

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