Download Angiosperms

Angiosperms
Earth’s dominant plants
Angiosperm Characteristics

Vascular

Flowering plants

Double fertilization

Seeds are covered in a
fruit

Dominant sporophyte
generation

Xylem – vessel
elements

Phloem – sieve tube
elements
2 Largest Classes
Eudicots
Monocots

Grasses, corn, palms

Mainly herbaceous

Parallel veins in leaves

Flower parts – multiples of
3

Seed – 1 cotyledon,
endosperm

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  pollen grain (immature male
gametophyte

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  gametophyte
(aka embryo sac)
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  3n cell
 endosperm
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


Broad leaves


efficient photosynthesis
Abscission


Vessel elements
Reduces water loss
Adaptability of
sporophyte generation