Exploring Plant Evolution and Adaptation | The Diversity of Kingdom Plantae

1. Plants A survey of Kingdom Plantae

3. Characteristics of Plants • All Plants are Producers - Photosynthetic • Plants are Multicellular • Plant cells have cell walls • Plants are Non Motile

4. Plant Evolution • Plants are thought to have evolved from Green Algae. • Modern Plants and Green Algae have the same type of chlorophyll, similar cell wall composition and both have starch as their food storing polysaccharide.

5. Green Algae

6. Green Algae may be unicellular or multicellular and primarily live in aquatic environments • Modern Plants however are adapted to life on land

7. Advantages of Life in Aquatic Environment • Constant source of water - no risk of desiccation • Nutrients are readily available • Water provides support • Water is a medium for the transport of gametes • They have a moist surface for gas exchange

8. Life on Land • In order to survive on land plants must posses strategies or adaptations that compensate for the aforementioned advantages of life in water

9. Plant Classification

11. Bryophytes • A common example of bryophytes are mosses

13. Bryophyte Characteristics • Have NO true roots, stems or leaves • Gas exchange occurs through small openings called stomates • Have NO Vascular tissue

14. Must live in moist areas • Usually Small in size - 2cm. • Are anchored to the ground by structures called Rhizoids • Gametophyte generation is dominant • Each Gametophyte is a separate sex

16. Why are Bryophytes limited to Moist environments • Sperm have to swim to egg • Only posses a thin cuticle so they are prone to desiccation.

17. Why Bryophytes are Limited in Size. • With no vascular tissue there is no support for large sizes . • Also due to no vascular tissue materials are transported via diffusion…..this can only occur over a small area.

18. Reproduction In Bryophytes • Bryophytes undergo what is called an Alternation of Generations • An alternation between a haploid gametopyte generation and a diploid sporophyte generation.

19. Alternation of Generations in Bryophytes • See diagram on page 476

20. Tracheophytes • Tracheophytes are characterized by the presence of vascular tissue • Have “True” Roots Stems and leaves • There are two groups of tracheophytes:

22. What is Vascular Tissue? • Vascular tissue are parts of plants that are responsible for the transport of materials throughout the plant. • 2 types of Vascular Tissue • Xylem - transports water and minerals • Phloem - transports “food”

23. Spore Producing Tracheophytes • An example of spore producing tracheophytes are Ferns

25. Characteristics of Spore Producing Tracheophytes • Vascular tissue • true roots,stems, and leaves • Thicker cuticle then Bryophytes • No seeds but spores

26. Sporophyte generation is dominant, Gametophyte generation is reduced • Gametophyte generation still dependent on water for reproduction • Both sex organs on one gametophyte

27. Alternation of Generations in Spore Producing Tracheophytes • See page 477

29. Seed Producing Tracheophytes

30. Gymnosperms and Angiosperms • These two groups of plants produce seeds. • Both have no need for water for reproduction and have true leaves, stems and roots. (needles are leaves). • In both the sporophyte is dominant (the plant is the sporophyte). The gametophytes are microscopic.

31. Gymnosperms • Conifers are gymnosperms. There seeds are in the female cones while pollen comes from the male cones. • They have advanced plant features (roots, leaves, stems) and usually restricted to harsh environments (cold). Why? • Thrive in cool climates, with poor soil, often found in moist seashore areas. • Some gymnosperms have leaves.

33. Life Cycle • They have a simple life cycle (page 479) and are often pollinated by wind. • Male gametophyte is the pollen grain • Female gametophyte is the Ovule • These gametophytes are contained within cones.

34. Life Cycle • Male cones release millions of pollen grains. • If a pollen grain lands on the ovule of a female cone a pollen tube will form • sperm will travel down the tube and fertilize the egg.

35. Life Cycle • A covering forms around the zygote and the food supply to form a seed. • When seed ripen the cones will open • seeds have papery wings and are dispersed by the wind.

36. Angiosperms • These are the most advanced plants and have adapted to a wide variety of habitats (everywhere you see flowers, you see angiosperms).

37. Angiosperms • These are the flowering plants: the reproductive structures of plants are located within the flower. • Male and female sex organs are in close proximity and are often placed to take advantage of wind or insects. • Pollen moves from one place to another to ensure fertilization of eggs. (see life cycle on page 480).

38. Types of Flowers Perfect Flowers • Flowers that have both male and female parts Imperfect Flowers • Flowers that have either male or female parts

40. Fertilization of a Flower • When a pollen grain lands on a stigma a pollen tube forms • The pollen tube grows down through the style • The tube nucleus directs the growth of the pollen tube • The sperm nuclei enter the ovule

41. Fertilization of a Flower • One sperm nucleus fuses with the egg to form a zygote • The other fuses with the two polar nuclei to form a cell that becomes the endosperm (Food Source) • This is know as double fertilization

42. Seed Structure After fertilization the ovule develops into a seed.

43. Fruit • After fertilization the ovary of the flower enlarges forming the fruit. The seed is contained in the fruit • As the fruit ripens the flower parts fall away.

44. Reasons for the success of Angiosperms • 1. Pollination is relatively easy (by wind, insects or self pollination) • 2. Flowers tend to attract insects (for pollen or nectar • 3. Seeds are protected by a seed coat (allowing seeds to pass undigested through most digestive tracts, then they grow in the free fertilizer)

45. Reasons for the success of Angiosperms • 4. Fruits are attractive to animals who in turn help disperse seeds (above). • 5. Seeds are able to suffer severe conditions such as fire, freezing, drought and then emerge when conditions are again suitable. • 6. Plants themselves have adapted to a wide variety of habitats.

46. Types of Angiosperms

47. Monocots vs Dicots • Vascular tissue • Parallel veins in leaves vs Netted Veins in leaves • Seeds • One Cotyledon vs Two Cotyledons • Flowers • petals in multiples of 3 vs petals in multiples of 4 or 5

48. Monocots vs Dicots

49. Special Structures