PGS 82 - 87

Plants With Seeds

Types of Plants with Seeds

Gymnosperms are trees and shrubs that produce seeds in cones or fleshy structures on stems.

Examples are pine, spruce, fir and ginkgo.Angiosperms produce their seeds within fruit.Examples are peach trees, grasses, oaks,

roses, and buttercups.

Characteristics of Seed Plants

They produce seeds which are nourished and protected.

Gametophytes are found living on and protected by the reproductive structures of the sporophyte.

Male gametophytes travel by wind or animals and are called pollen.

They still have a two part life cycle and can live in most places.

What’s So Great about Seeds?

A seed (which develops after fertilization) is made up of: a young sporophyte, stored food, and a tough seed coat.

The young plant is nourished by the stored food until it can produce its own.

In contrast, spores must develop where it can begin photosynthesis as soon as it begins to grow.

Gymnosperms

Seeds of gymnosperms are not enclosed in a fruit.

There are four groups of gymnosperms: conifers, ginkgoes, cycads and gnetophytes.

Conifers are pines, spruces and firs.Ginkgoes are just the ginkgo tree.Cycads are tropical plants with cones. Gnetophytes are shrubs in dry areas.

Gymnosperm life cycle

Gymnosperms that use cones to carry seeds produce both male and female cones.

The male gametophyte is pollen and the female is an egg.

Wind carries pollen from the male cone to the female cone on the same plant or different plants (called pollination).

The egg is fertilized when the pollen and egg unite.

It develops into a seed in the female cone.Once it is mature, it drops to the ground to

germinate and grow into a tree.We use conifers for wood, paper, soap, paint

and ink

Angiosperms

Angiosperms are flowering plants and are the most abundant plants today.

There are over 235,000 species.They have a vascular system.All angiosperms have flowers and produce

fruits.

What are Flowers For?

Flowers help angiosperms reproduce.Some need wind for pollination and some rely

on animals to spread pollen for them.

What are Fruits For?

Fruits help to ensure that seeds survive as they are transported to areas where new plants can grow.

Fruits surround and protect seeds.Some fruits have structures that help the

wind carry them away.Some fruits have structures that attract

animals to eat the fruit or to attach to animals.

Monocots and Dicots

Angiosperms have two classes: monocots and dicots.

The difference is in the number of cotyledon in their seeds.

A cotyledon is a seed leaf found inside the seed.

Monocots have one, dicots have two. Monocots are grasses, orchids, onions, and

palms.Dicots are roses, cacti, sunflowers, and peas.

The Importance of Angiosperms

They provide food for animals.Humans depend on flowering plants and use

them as major food crops like corn, wheat and rice.

Some are used as furniture and toys. Some produce cotton for clothes or ropes.Some are even used as medicines and

perfume oils.