1. Plant Diversity

2. What Is A Plant? Multicellular eukaryotes Cell walls with cellulose
Photosynthesis using green pigments
chlorophyll a and b
Autotrophs
Some are parasites or saprobes

3. What Plants Need To Survive
Sunlight
Water and minerals
Gas exchange
Movement of water and nutrients

4. Early Plants For most of Earth’s history plants did not exist
Origins in the water
Green algae: the first plants evolved from an organism much like the multicellular green algae living today
Depended on water to complete their life cycles

5. The First Plants Life on land favored the evolution of plants:
More resistant to the drying rays of the sun
More capable at conserving water
More capable of reproducing on dry land

6. The First Plants Like today’s mosses Gave rise to the plants of today!
Non-vascular Plants
Seedless Vascular Plants
Gymnosperms
Angiosperms
Four groups based on:
Water-conducting tissues
Seeds
Flowers
Today scientists can classify plants more precisely by comparing DNA sequences of various species

7. The Plant Life Cycle: Alternation of Generations
Haploid gametophyte (N): gamete-producing phase of an organism
Diploid sporophyte (2N): spore-producing phase of an organism

8. SEEDLESS PLANTS

9. Green Algae First plants Mostly aquatic
Fresh and salt water, some moist areas on land
Absorb water and nutrients from surroundings
Life Cycle: switch between haploid and diploid
No specialized cells

10. Bryophytes Mosses, liverworts, hornworts Depend on water
Sperm swim through water to reach eggs of other plants
No vascular tissue
Can draw up water by osmosis only a few cm above the ground

11. Mosses The most common bryophytes
Well adapted to wet habitats and nutrient-poor soils
Gametophyte dominant
Reproduce  produce thin stalks with sporophyte
Rhizoids: long, thin cells that anchor them in the ground and absorb water and minerals from the surrounding soil
No true roots

12. Life Cycle of A Moss Archegonia: produces eggs
Antheridia: produces sperm
Sperm of the bryophyte must swim to an egg for fertilization to occur
A diploid zygote results from fertilization
Sporophyte: the zygote
Grows out of the gametophyte and depends on it for water and nutrients
When ready, haploid spores are released to start the cycle again

13. VASCULAR PLANTS

14. Vascular Plants: Tracheophytes
Vascular tissue: a type of tissue that is specialized to conduct water and nutrients through the body of the plant
Tracheid: hollow plant cell in xylem tissue with thick cell walls that resist pressure
One of the great evolutionary innovations of the plant kingdom!

15. Vascular Plants Xylem and Phloem: Allow vascular plants to:
move fluids throughout the plant body
even against the force of gravity
Allow vascular plants to:
grow upright
reach great heights

16. Structure of Vascular Tissue
Xylem: vascular tissue that carries water upward from the roots to every part of the plant
Phloem: vascular tissue responsible for the transport of nutrients & carbohydrates produced by photosynthesis

17. Vascular Plants Roots: absorb water and minerals
Leaves: photosynthetic organisms that contain one or more bundles of vascular tissue
Stems: supporting structures that connect roots and leaves, carrying water and nutrients between them

18. SEEDLESS VASCULAR PLANTS

19. Seedless Vascular Plants
Club mosses, horsetails, and ferns
Ferns have survived Earth’s long history in numbers greater than any other group of spore-bearing vascular plants
More than 11,000 species live today
Strong roots
Rhizomes: creeping or underground stems
Fronds: large leaves
Can thrive in areas with little light
Most abundant in wet or seasonably wet habitats

20. Life Cycle of Ferns Sporophyte = Dominant
Produce haploid spores on the underside of their fronds in sporangia
Spores are released
Spores germinate into haploid gametophytes
Diploid zygote is produced from fertilization
Sporophyte grows and the gametophyte withers away

21. SEED PLANTS

22. Seed Plants Seeds include: Seed plants are divided into two groups:
Acorns, pine nuts, dandelion seeds, kernels of corn, etc.
Seed plants are divided into two groups:
Gymnosperms
Angiosperms

23. Seed Plants Reproduction free from water Can live just about anywhere
Adaptations to reproduce without water:
Flowers or cones
Transfer of sperm by pollination
Protection of embryos in seeds

24. Cones and Flowers
Gametophyte of seed plants grow and mature within sporophyte structures called cones (gymnosperms) and flowers (angiosperms)

25. Pollen Pollen Grain: male gametophyte is contained in a tiny structure
The wind, insects, birds and small mammals may carries pollen grains
Pollination: the transfer of the pollen grain to the female gametophyte

26. Evolution of Seed Plants
The seed was very important evolutionarily
Seed: embryo of a plant encased in a protective covering and surrounded by a food supply
Mosses and ferns underwent major adaptive radiation mya
Land environments were much wetter than they are today
As the land became drier, it became harder for seedless plants to survive
Fossils of seed-bearing plants exist from almost 360 mya
The original seed plants resembled ferns

27. GYMNOSPERMS

28. Gymnosperms…Cone Bearers
The most ancient surviving seed plants
Include cycads, ginkgoes, and conifers
“Naked Seed”: these plants all reproduce with seeds that are exposed

29. Conifers The most common gymnosperms with more than 500 known species
Pines, spruces, firs, cedars, sequoias, redwoods, yews
Some, like the bristlecone pine tree, can live for more than 4000 years
Others, such as the giant redwood, can grow to more than 100 meters in height

30. Ecology of Conifers
Thrive in a wide variety of habitats: on mountains, in sandy soil, and in cool, moist areas
Leaves have adaptations to dry conditions
The leaves are long and thin, like pine needles
This shape reduces the surface area from which water can be lost
Waxy layer also prevents water loss
Most are evergreens: they retain their leaves through the year

31. Cones Pollen Cones (male cones): produce pollen
Seed Cones (female cones): produce female gametophytes in two ovules
The complete life cycle takes 2 years to complete
The direct transfer of pollen to the female cone allows fertilization to take place without the need for gametes to swim through standing water

32. ANGIOSPERMS

33. Angiosperms…Flowering Plants
Flowering plants first arrived about 135 mya
Originated on land and became the dominant plant life on Earth
The majority of living plant species reproduce with flowers

34. Flowers: An Evolutionary Advantage
Attract animals which transport pollen from flower to flower
More efficient than wind pollination of most gymnosperms
Flowers contain ovaries, which surround and protect the seeds

35. Angiosperms…”Enclosed Seeds”
After pollination, the ovary develops into a fruit, which protects the seed and aids in its dispersal
Fruit: thick wall of tissue surrounding the seed
Adds to the success of angiosperms

36. Monocots and Dicots Monocots Dicots
Angiosperm whose seeds have one cotyledon
Parallel veins
Floral parts often in multiples of 3
Stem vascular bundles are scattered
Fibrous root
Angiosperm whose seeds have two cotyledons
Branched veins
Floral parts often in multiples of 4-5
Stem vascular bundles are arranged in a ring
Taproot

37. Comparing Monocots and Dicots

38. Woody Plants
Woody plants are made primarily of cells with thick cell walls that support the plant body
Trees
All types!
Shrubs
Blueberries, rhododendrons, roses
Vines
Grapes and ivy

39. Herbaceous Plants
Smooth and non-woody plants that do not produce wood as they grow
Dandelions, zinnias, petunias, sunflowers

40. Growing Season
Annuals: Flowering plants that complete a life cycle within one growing season
Garden plants, marigolds, petunias, pansies, zinnias, wheat and cucumbers too!
Biennials: Flowering plants that complete a life cycle in two years
Primrose, parsley, celery, foxglove
Perennials: Flowering plants that live for more than two years
Peonies, asparagus, grasses: herbaceous perennials
Palm trees, sagebrush, maple trees, honeysuckle: woody perennials