1. Plants

2. Objective Students will be able to
Describe the characteristics of plants

3. Plants An Overview of Plants
Between 260,000 and 300,000 different species
Have adapted to almost every environment

4. Plants have some general characteristics:
An Overview of Plants
Plants have some general characteristics:
Roots or root-like structures
Can perform photosynthesis
Has cells that are different from those of other organisms

5. Plant cells An Overview of Plants
Cell walls, which provide structure and protection.
Green pigment chlorophyll
Central vacuole, which regulates water content.

6. An Overview of Plants
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.

7. An Overview of Plants

8. An Overview of Plants
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.

9. When plants moved to land, they had to adapt to new conditions.
An Overview of Plants
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.

10. When plants moved to land, they had to adapt to new conditions.
An Overview of Plants
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.

11. An Overview of Plants 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.

12. Objective Students will be able to: Identify seedless plants
Distinguish between vascular and nonvascular seedless plants
Explain a pioneer species
Explain how humans use seedless plants

13. Seedless Plants Nonvascular plants Seedless Vascular 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

14. Nonvascular plants
Water is absorbed and distributed directly through cell membranes and cell walls.
Grow in damp environments
Reproduce by spores rather than seeds

15. Nonvascular plants Examples of nonvascular plants:
Mosses - green, leaflike growths arranged around a central stalk

16. Nonvascular plants Examples of nonvascular plants:
Liverworts - flattened, leaflike bodies

17. Nonvascular plants Examples of nonvascular plants:
Hornworts - have only one chloroplast in each of their cells

18. Nonvascular plants Pioneer species
Organisms that are the first to grow in new or disturbed areas and which change environmental conditions

19. 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

20. Seedless Vascular plants
Examples of seedless vascular plants
Ferns - largest group of seedless vascular plants
Have stems, leaves, and roots
Leaves are called fronds
Reproduce by spores found on the back of their fronds

21. Seedless Vascular plants
Examples of seedless vascular plants
Club mosses - needlelike leaves

22. Seedless Vascular plants
Examples of seedless vascular plants
Horsetails - jointed stem with a hollow center

23. 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.

24. Objective Students will be able to:
Describe the characteristics of a seed plant
Describe the anatomy of a seed plant
Distinguish between gymnosperms and angiosperms
Compare and contrast monocots and dicots
Explain how humans use seed plants

25. Seed Plants Have leaves, stems, roots, and vascular tissue
Reproduce by seeds, which contain an embryo and stored food

26. Seed Plants
Leaves
Trap light and make food through photosynthesis.

27. 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.

28. Seed Plants
Leaves
Palisade layer - contains chloroplasts, where most food is made
Spongy layer - loosely arranged cells and air

29. Seed Plants
Stems
allow the movement of materials between leaves and roots.
Usually above ground
Support the branches, leaves, and flowers
May store food

30. Seed Plants Stems: Herbaceous stems—soft and green
Woody stems—hard, rigid, and woody

31. 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.

32. 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

33. Seed Plants
There are two kinds of seed plants
Gymnosperms
Angiosperms

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

35. Gymnosperms
Four divisions:
Conifers
Cycads
Ginkgoes
Gnetophytes

36. Gymnosperms
Conifers
Cone-bearing, reproducing because of male and female cones
Woody
Most are trees, some are shrubs
First trees on earth

37. Gymnosperms Conifers are the oldest living things on earth
Left: oldest tree is a bristle-cone pine, the Methuselah tree is 4,839 years old
Right: Newly discovered in Sweden, this spruce has a root system that is 9,600 years old.

38. Gymnosperms Conifers are the oldest living things on earth
NOVA Online | Methuselah Tree

39. Gymnosperms Conifers are the tallest living things on earth
Hyperion is the newly discovered sequoia that is feet tall, beating out the Stratospheric Giant at feet.

40. Gymnosperms Conifers are the widest living things on earth
Left: the General Sherman Redwood at 102 ft. around
Right: The Tree at Santa Maria del Tule, a Montezuma Cypress at 164 ft. in circumference

41. Gymnosperms Conifers are the widest living things on earth
This is known as the “Tree of a hundred horses.”
At 204 ft around it was the widest tree ever measured
It now grows in three pieces

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

43. Angiosperms Two groups: Monocots One cotyledon in seed
Vascular bundles scatteres
Flower parts in multiples of three
Parallel veins on leaves

44. Angiosperms Two groups: Dicots Two cotyledons inside their seeds
Vascular bundles in rings
Flower parts in multiples of four or five
Branching veins

45. Angiosperms 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

46. Seed Plants
Seed plants are very important because they have useful purposes
Wood for construction
Paper products.
Angiosperms form the basis of diets for most animals, including humans.