Diversity of Flowering PlantsMr. Chapman

Biology 20

Gymnosperms and AngiospermsRecall the difference between gymnosperms and

angiosperms:

A gymnosperm is a seed-bearing, vascular plant that does not enclose its seeds in a fruit.

An angiosperm is a seed-bearing, vascular plant that DOES enclose its seeds in some type of fruit.

Different Seed-BearersGymnosperm Angiosperm

Flowers and PollinationGymnosperms, which do not have flowers, rely on the

wind for pollination.

Because gymnosperms do not have flowers, no insects travel to them to feed off their nectar, and hence gymnosperms do not have pollinators to help them spread their genetic material in the environment.

Flowers and PollinationFlowers allow for more efficient pollination.

Insects, which in this case we will call pollinators, feed on the nectar a flower plant produces (the sweet, sugary solution produced in some species of flower).

When insects feed on this nectar, they get the pollen of the plant on themselves. Recall that this pollen will produce the male gametophytes, or sperm, that will eventually fertilize a plant.

Flowers and PollinationWhen the insect moves to a different flower (of the same

species) to feed, the insect will carry the pollen from one flower to another, fertilizing the new plant.

Because of this mutualistic relationship, flowering plants pollinated by animals do not need to produce nearly as much pollen as the gymnosperms, which rely on the wind to randomly disperse their pollen.

Diversity of Fruit

Diversity of FruitRecall that a fruit is simply a ripened ovary of a flowering

plant.

For example, the shells of sunflower plants and peanuts are also fruits. Fruit play an important role in seed dispersal because they are a tasty food source for animals, which digest the food but not the seeds.

TWO Types of Flowering PlantsBotanists (people who study plants for a living) classify flowering

plants into two groups based on their types of seeds:

- Monocots: flowering plants with one embryonic leaf inside a seed

- Dicots: flowering plants with one embryonic leaf inside a seeed.

- Monocots and Dicots have typically have major differences in plant structure. “Cots” is an abbreviation for cotyledon, an embryonic leaf inside a seed.

Monocots vs. Dicots