Plants

PlantsPlants

Objective Objective Students will be able to Students will be able to

Describe the characteristics of Describe the characteristics of plantsplants

An Overview of Plants

Plants Between 260,000 and 300,000 different

species Have adapted to almost every

environment


Plants have some general characteristics: Roots or root-like structures Can perform photosynthesis Has cells that are different from those

of other organisms


Plant cells Cell walls, which provide structure and

protection.

Green pigment chlorophyll Central vacuole, which regulates water

content.


Earliest plants were probably green algae, dating back to 420 m.y.a.

Cone-bearing plants show up around 300 m.y.a.

Flowerings plants came into existence around 120 m.y.a.


Scientists think plants probably evolved from green algae in the sea because:Plants and green algae have the same

types of chlorophyll and carotenoids.Fossils of early plants are similar to the

ancient green algae.


When plants moved to land, they had to adapt to new conditions.

More sunlight and carbon dioxide were available.

Plants developed a cuticle—a waxy, protective layer secreted onto the surface of the plant which holds water in and allows plants to live in drier conditions.


When plants moved to land, they had to adapt to new conditions.

Cell walls developed cellulose, a chemical compound that provides structure and support, which allows plants to stand upright on land.

Water-resistant spores and seeds enabled plants to reproduce on land.


Plant classification

Vascular plants use tube-like structures that carry water and nutrients throughout the plant.

Nonvascular plants lack tube-like structures and use other ways to move water and nutrients.

ObjectiveObjective Students will be able to:Students will be able to:

Identify seedless plants Identify seedless plants Distinguish between vascular and Distinguish between vascular and

nonvascular seedless plantsnonvascular seedless plants Explain a pioneer speciesExplain a pioneer species Explain how humans use seedless Explain how humans use seedless

plantsplants

Seedless Plants

Nonvascular plants Very small plants that have rhizoids

rather than roots Seedless Vascular plants

Reproduce by spores, but have vascular tissue that carries water and nutrients throughout the plant

Nonvascular plants Water is absorbed and distributed

directly through cell membranes and cell walls.

Grow in damp environments Reproduce by spores rather than

seeds

Examples of nonvascular plants: Mosses - green,

leaflike growths arranged around a central stalk

Nonvascular plants

Nonvascular plants Examples of

nonvascular plants: Liverworts -

flattened, leaflike bodies

Nonvascular plants Examples of

nonvascular plants: Hornworts - have

only one chloroplast in each of their cells

Nonvascular plants Pioneer species

Organisms that are the first to grow in new or disturbed areas and which change environmental conditions

Seedless Vascular plants

Reproduce by spores, but have vascular tissue that carries water and nutrients throughout the plant

Can grow bigger and thicker than nonvascular plants

Seedless Vascular plants Examples of seedless vascular

plants Ferns - largest group of

seedless vascular plantsHave stems, leaves, and rootsLeaves are called frondsReproduce by spores found on

the back of their fronds


plants Club mosses - needlelike leaves


plants Horsetails - jointed stem with a

hollow center

Seedless plants Seedless plants are important because

they have many useful purposes Fuel—decaying seedless plants are

compressed into peat and eventually coal

Soil conditioners Ferns can be used for weaving material

and basketry.

ObjectiveObjective Students will be able to:Students will be able to:

Describe the characteristics of a seed plantDescribe the characteristics of a seed plant Describe the anatomy of a seed plantDescribe the anatomy of a seed plant Distinguish between gymnosperms and Distinguish between gymnosperms and

angiospermsangiosperms Compare and contrast monocots and dicotsCompare and contrast monocots and dicots Explain how humans use seed plantsExplain how humans use seed plants

Seed Plants

Have leaves, stems, roots, and vascular tissue

Reproduce by seeds, which contain an embryo and stored food

Seed Plants Leaves

Trap light and make food through photosynthesis.

Seed Plants Leaves

Epidermis - a thin layer of cells on the upper and lower surfaces of a leaf

May have a waxy cuticle coating the epidermis Stomata—small openings in the epidermis that

allow carbon dioxide, water, and oxygen to enter and exit a leaf

Each stoma is surrounded by two guard cells that open and close it.

Seed Plants

Leaves Palisade layer -

contains chloroplasts, where most food is made

Spongy layer - loosely arranged cells and air

Seed Plants Stems

allow the movement of materials between leaves and roots.

Usually above ground Support the branches, leaves, and

flowers May store food

Seed Plants Stems:

Herbaceous stems—soft and green

Woody stems—hard, rigid, and woody

Seed Plants Roots

Roots collect water and nutrients from the ground.

Roots anchor plants so they don’t blow away.

May store food or water.

Seed Plants Vascular tissue

Xylem tissue—transports water from the roots throughout the plant

Phloem tissue—moves food from where it is made to other parts of the plant

Cambium tissue—produces new xylem and phloem cells

Seed PlantsSeed Plants There are two kinds of seed plantsThere are two kinds of seed plants

GymnospermsGymnosperms AngiospermsAngiosperms

GymnospermsGymnosperms Vascular plants that produce

seeds that are not protected by fruit Oldest trees alive Gymnosperms have no flowers. Leaves are often needlelike or scalelike

GymnospermsGymnosperms

Four divisions: Conifers Cycads Ginkgoes Gnetophytes

GymnospermsGymnosperms ConifersConifers

Cone-bearing, reproducing because of Cone-bearing, reproducing because of male and female conesmale and female cones

Woody Woody Most are trees, some are shrubsMost are trees, some are shrubs First trees on earthFirst trees on earth


Conifers are the oldest living things on earth

Left: oldest tree is a Left: oldest tree is a bristle-cone pine, the bristle-cone pine, the Methuselah tree is 4,839 Methuselah tree is 4,839 years old years old

Right: Newly Right: Newly discovered in Sweden, discovered in Sweden, this spruce has a root this spruce has a root system that is 9,600 system that is 9,600 years old. years old.


Conifers are the oldest living things on earth

NOVA Online | MethusNOVA Online | Methuselah Treeelah Tree


Conifers are the tallest living things on earth

Hyperion is the newly Hyperion is the newly discovered sequoia that is discovered sequoia that is 379.1 feet tall, beating out 379.1 feet tall, beating out the Stratospheric Giant at the Stratospheric Giant at 370.5 feet.370.5 feet.


Conifers are the widest living things on earth

Left: the General Left: the General Sherman Redwood at Sherman Redwood at 102 ft. around 102 ft. around

Right: The Tree at Right: The Tree at Santa Maria del Tule, Santa Maria del Tule, a Montezuma Cypress a Montezuma Cypress at 164 ft. in at 164 ft. in circumference circumference


Conifers are the widest living things on earth

This is known as the This is known as the “Tree of a hundred “Tree of a hundred horses.”horses.”

At 204 ft around it At 204 ft around it was the widest tree was the widest tree ever measuredever measured

It now grows in three It now grows in three piecespieces

AngiospermsAngiosperms

Vascular plants that flower and have fruit that contains seeds Fruit develops from flowers. Most fruit contains seeds.


Two groups:

MonocotsOne cotyledon in seedVascular bundles scatteresFlower parts in multiples of threeParallel veins on leaves


Two groups:

DicotsTwo cotyledons inside their seeds Vascular bundles in ringsVascular bundles in rings Flower parts in multiples of four or fiveFlower parts in multiples of four or five Branching veinsBranching veins

AngiospermsAngiosperms Different angiosperms have different

life cycles: Annual - the plant’s life cycle is completed

within one year Biennial - the plant’s life cycle is completed

in two years Perennial - takes more than two years to

grow to maturity

Seed PlantsSeed Plants Seed plants are very important Seed plants are very important

because they have useful purposesbecause they have useful purposes Wood for construction Paper products. Angiosperms form the basis of diets for

most animals, including humans.

Plants

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