1. Flowering plants
Section 22.4

2. Flowering plants (angiosperm) overview
Most abundant plant species on Earth
First appeared 135 million years ago
Flower – reproductive organ
Contain ovaries – surround and protect seeds
Gives rise to name angiosperm – ‘enclosed seed’.
Reproduce via sexual reproduction
After fertilization, fruit development provides protection for the seed

3. Why do they have flowers?
Attract animals such as bees, moths and hummingbirds
Attracted by scent, color or shape
Take pollen away when they leave
Pollinate as they move – more efficient than wind

4. Why do they have fruits? All fruits contain one or more mature ovaries
Wall helps to disperse seeds inside – carrying away from parent plant
Can be spread by animals….

5. How do you classify angiosperms?
Originally classified on the basis of number of seed leaves (Cotyledons)
One seed leaf – monocots
Two seed leaves – dicots
Actually, life is more complicated
Ancient chinese fruiting plant fossil (Archaefructus – oldest known plant with reproductive organs found resembling modern flowers)
Can not be classified as either monocot or dicot
Amborella – from pacific island of New Caledonia also can’t be classified as either
Now monocots are placed in a single group, but dicots are divided into a variety of distinct and different categories
Dicot not used for classification, but still used today

6. What If you aren’t a scientist?
Alternative widely used classifications exist
Angiosperms can be grouped according to:
Number or seed leaves
Strength and composition of stem
Number of growing seasons

7. Monocots vs Dicots

8. Woody and Herbaceous plants
Flowering plants can be divided on the basis of stem characteristics
Woody plants – plants made with cells that have a thick cell wall which supports plant body
Include trees, shrubs and bines
Herbaceous plants – do not produce wood as they grow
Smooth and nonwoody

9. Annuals, Biennials and Perennials
Some flowers plants will grow, flower and die in a single year
Other grow from year to year
Lifespan determined by genetic and environmental factors
Harsh environmental conditions can shorten life cycles

10. Summary questions
What are the key features of angiosperm reproduction? What aspects are unique to angiosperms?
What is the importance of a fruit?
How can angiosperms be categorized?
How are scientific and everyday classification methods different?

11. Writing assignment
Compare and contrast seeded and seedless plants? What are the main differences in terms of their structure and life cycle?
It may help to produce a summary graphic organizer before you begin