Seed PlantsChapter 12 Section 3

Objectives:

Describe 3 ways that seed plants differ from

seedless plants

Describe the structure of seeds

Compare angiosperms & gymnosperms

Explain the economic & environmental

importance of gymnosperms & angiosperms

FYI: The Millennium Seed Bank

Royal Botanic Gardens in Kew, England

◦ Collecting seeds from 24,000 plant species

around the world

◦ 50,000 species may become extinct in the

next 30 years

◦ Ensures the survival of plants that stabilize

soil, provide food, medicine, and building

material

FYI: Sea Bean (genus Mucuna)

Largest seed pod in the world

Floats from river to ocean, 1000’s of miles

before it is washed to shore

http://waynesword.palomar.edu/images/mucuna4b.gif http://www.ncaquariums.com/askaquarium/ataimg/seabeans.jpg

Seed Plants:

2 groups of vascular plants that produce

seeds:

◦ Gymnosperms

Trees & Shrubs that do not have flowers or fruit

◦ Angiosperms

Have flowers and seeds that are protected by fruit

Characteristics of Seed Plants

Similarities: seed and seedless plants both

alternate between a 2 stage life cycle

◦ Sporophyte

◦ Gametophyte

Characteristics of Seed Plants:

Differences:

◦ Produce seeds; nourish and protect young

sporophytes

◦ Gametophytes do not live independently of

the sporophyte; tiny; form within the

reproductive structures of the sporophyte

◦ The sperm of seed plants do not need water

to reach an egg; form inside pollen – can be

transported by wind or animals

Pollen:

The tiny granules that contain the male

gametophyte of seed plants

Seed Plants:

Because of these characteristics, seed

plants can live just about anywhere!

Most common plants on Earth today

The Structure of Seeds:

A seed forms after fertilization

3 Parts:

◦ Young plant: Sporophyte

◦ Stored food: Cotyledons (seed leaves)

◦ Seed coat: surrounds and protects the young

plant

Seed Structure:

http://www.uen.org/utahlink/tours/admin/tour/14719/14719lr001135.gif

The Structure of Seeds:

Advantages over seedless plants:

◦ Young plant uses the stored food in the seed

◦ Can be spread by animals (more efficient)

Gymnosperms:

Do not have flowers or fruit

Seeds are usually protected by a cone

4 Groups:

◦ Conifers

◦ Ginkgoes

◦ Cycads

◦ Gnetophytes

Importance of Gymnosperms:

Conifers: used for building materials, paper products, anti-cancer drugs

Pine trees: produce resin (used to make soap, turpentine, paint, ink)

Gnetophytes: anti-allergy drugs

All are popular in gardens and parks

Gymnosperms:

Gymnosperm Life Cycle:

Most familiar gymnosperm: conifer

(“cone-bearing”) – have male & female

cones

Spores of each type of cone become tiny

gametophytes

Gymnosperm Life Cycle:

Male gametophytes are found in pollen (pollen contain sperm)

Female gametophytes produce eggs

Transfer of pollen from male to female cones = pollination

Fertilized egg develops into a young sporophytewithin the female cone

Released under special circumstances (ex: forest fire)

Gymnosperm Life Cycle:

http://img.sparknotes.com/figures/9/9f79f1dbce762884bf644e4ac8450061/gymnospermlifecycle.gif

Angiosperms:

Vascular plants that produce flowers and

fruits

Most abundant plants today

235,000 species

In almost every land ecosystem

Angiosperm Reproduction:

Flowers help angiosperms reproduce

◦ Some depend on the wind for pollination

◦ Others have flowers that attract animals

Fruits surround and protect seeds

◦ Depend on the wind to carry them

◦ Other fruits attract animals to eat them or

are carried (ex: burrs)

2 Kinds of Angiosperms:

2 Classes of Angiosperms

◦Monocots

◦Dicots

Monocots:

One cotyledon

Leaves with parallel veins

Flower parts in threes

Scattered bundles of vascular tissue

Ex: Grasses, orchids, onions, lilies,

palms

Monocots:

http://www.agen.ufl.edu/~owens/age2062/OnLineBiology/OLBB/www.emc.maricopa.edu/faculty/farabee/BIOBK/monocots_1.gif

Dicots:

2 cotyledons

Ex: roses, cactuses, sunflowers, peanuts,

peas

Leaves with branching veins

Bundles of vascular tissue are in a ring

Dicots:

http://www.agen.ufl.edu/~owens/age2062/OnLineBiology/OLBB/www.emc.maricopa.edu/faculty/farabee/BIOBK/DICOTS.gif

Importance of Angiosperms:

Provide food for land animals

Part of food chain

Major food crops for people (corn, rice,

wheat)

Oak trees (building materials)

Cotton or flax (clothing or rope)

Medicines, rubber, perfume oils

Angiosperms:

Quick Quiz:

How are gymnosperms and angiosperms

different?

How are flowering plants important?