The Plant Kingdom: Flowering Plants

1. The Plant Kingdom: Flowering Plants Chapter 25

2. LEARNING OBJECTIVE 1 • Summarize the features that distinguish flowering plants from gymnosperms

3. KEY TERMS • ANGIOSPERM • Traditional name for flowering plants • A large, diverse phylum of plants that form flowers for sexual reproduction and produce seeds enclosed in fruits

4. Flowering Plants • Like gymnosperms: • Flowering plants have vascular tissues and produce seeds • Unlike gymnosperms: • Ovules of flowering plants are enclosed within an ovary

5. KEY TERMS • OVULE • Structure in the ovary that contains a female gametophyte and develops into a seed after fertilization • OVARY • Base of a carpel or fused carpels that contains ovules and develops into a fruit after fertilization

6. Orange Fruit Development

7. LEARNING OBJECTIVE 2 • Describe the ecological and economic significance of the flowering plants

8. Ecology and Economy • Our survival as a species depends on flowering plants • Major food crops • Products • Cork, rubber, tobacco, coffee, chocolate, aromatic oils for perfumes • Valuable lumber • Fibers and medicines

9. Economic Botany • Subdiscipline of botany that deals with plants of economic importance • Most of these are flowering plants

10. LEARNING OBJECTIVE 3 • Distinguish between monocots and eudicots, the two largest classes of flowering plants • Give specific examples of each class

11. KEY TERMS • COTYLEDON • The seed leaf of a plant embryo, which may contain food stored for germination

12. KEY TERMS • MONOCOT • One of two main classes of flowering plants; monocot seeds contain a single cotyledon • Monocots have floral parts in threes • Monocots include grasses, orchids, irises, onions, lilies, palms

13. KEY TERMS • EUDICOT • One of two main classes of flowering plants; eudicot seeds contain two cotyledons • Eudicots have floral parts in fours or fives • Eudicots include oaks, roses, mustards, cacti, blueberries, sunflowers

14. Monocots and Eudicots

15. Petal Sepal Anther of stamen Stigmas of pistil (a) Monocots, such as this nodding trillium (Trillium cernuum), have their floral parts in threes. Note the three green sepals, three white petals, six stamens, and three stigmas (the compound pistil consists of three fused carpels). Fig. 25-2a, p. 488

16. Petal Anther of stamen Pistils (b) Most eudicots such as this Tacitus bellus have floral parts in fours or fives. Note the five petals, 10 stamens, and five separate pistils. Five sepals are also present but barely visible against the background. Fig. 25-2b, p. 488

17. LEARNING OBJECTIVE 4 • Briefly explain the life cycle of a flowering plant • Describe double fertilization

18. Life Cycle • Flowering plants undergo an alternation of generations: • Sporophyte generation is larger and nutritionally independent • Gametophyte generation is reduced to only a few microscopic cells

19. KEY TERMS • DOUBLE FERTILIZATION • A process in the flowering plant life cycle in which there are two fertilizations • One results in formation of a zygote • Second results in formation of endosperm

20. KEY TERMS • ENDOSPERM • The 3n nutritive tissue formed at some point in the development of all angiosperm seeds

21. Life Cycle: Flowering Plants

22. Pollination Developing pollen tube of mature male gametophyte Each microspore develops into a pollen grain Embryo sac (mature female gametophyte) 6 5 Pollen grain (immature male gametophyte) Microspore Tetrad of microspores Pollen tube 3 Polar nuclei Megaspore Egg nucleus Two sperm cells HAPLOID (n) GAMETOPHYTE GENERATION Meiosis Double fertilization Ovary DIPLOID (2n) SPOROPHYTE GENERATION 7 Megaspore mother cell Endosperm (3n) 2 4 Zygote (2n) Megasporangium (ovule) Fruit 8 Embryo Seed Microspore mother cells within microsporangia Seed coat 1 Seedling Anther Flower of mature sporophyte Fig. 25-3, p. 490

23. Pollen Grains

24. LEARNING OBJECTIVE 5 • Discuss some of the evolutionary adaptations of flowering plants

25. Adaptations of Flowering Plants 1 • Reproduce sexually by forming flowers • Form seeds within fruits after double fertilization

26. Adaptations of Flowering Plants 2 • Have efficient water-conducting vessel elementsin xylem and carbohydrate-conducting sieve-tube elementsin phloem • Have pollen grains transported by wind, water, insects, other animals

27. KEY TERMS • APOMIXIS • A type of reproduction in which fruits and seeds are formed asexually

28. Adaptability of Flowering Plants

29. LEARNING OBJECTIVE 6 • Trace the evolution of flowering plants from gymnosperms

30. Evolution of Flowering Plants • Probably descended from ancient gymnosperms with specialized features • leaves with broad, expanded blades and closed carpels • Probably arose only once

31. Drimys piperita Carpel

32. Carpel Fused margin Ovules Stigma Ovary Style Stigma (a) The carpel resembles a folded leaf in which the ovules borne on its upper surface are enclosed. (b) A cross section of the carpel, cut along the dashed line in (a). Fig. 25-6, p. 493

33. Fossil Angiosperms

34. Pistils Scars on reproductive axis Carpel Ovule (a) The oldest known fossil angiosperm. This fossil of the extinct plant Archaefructus shows a carpel-bearing stem. It was discovered in northeastern China and is about 125 million years old. (b) The fossilized flower of the extinct plant Archaeanthus linnenbergeri, which lived about 100 mya. The scars on the reproductive axis (receptacle) may show where stamens, petals, and sepals were originally attached but abscised (fell off). Many spirally arranged pistils were still attached at the time this flower was fossilized. Fig. 25-7, p. 494

35. Evolution of Flowering Plants

36. Basal Angiosperms Core Angiosperms Monocots Amborella Water lilies Star anise Eudicots Magnoliids Evolution of vessel elements Evolution of flowering plants (a) One hypothesis of relationships among the flowering plants, based on fossil and molecular evidence. Amborella, water lilies, and star anise are living plants whose ancestors apparently branched off the angiosperm family tree early. These early groups were followed by the magnoliids, the monocot branch, and the eudicots. Fig. 25-8, p. 495

37. LEARNING OBJECTIVE 7 • Distinguish between basal angiosperms and core angiosperms

38. KEY TERMS • BASAL ANGIOSPERM • One of three groups of angiosperms thought to be ancestral to all other flowering plants • CORE ANGIOSPERM • Group including most angiosperm species • Divided into three subgroups: magnoliids, monocots, and eudicots

39. KEY TERMS • MAGNOLIID • One of the groups of flowering plants • Core angiosperms once classified as “dicots,” but molecular evidence indicates they are neither eudicots nor monocots • Includes species in magnolia, laurel, and black pepper families, several related families

40. LEARNING OBJECTIVE 8 • Briefly describe the distinguishing characteristics and give an example or two of each of the following flowering plant families: magnolia, walnut, cactus, mustard, rose, pea, potato, pumpkin, sunflower, grass, orchid, and agave

41. Flowering Plant Families 1 • More than 300 families • Magnolia family • Important ornamentals and source of timber • Examples: southern magnolia, tuliptree

42. Magnolia Family

43. Fig. 25-9, p. 497

44. Flowering Plant Families 2 • Walnut family • Provides nuts for food, wood for furniture • Examples: English walnut, black walnut, pecan • Cactus family • Important as ornamentals • Examples: prickly pear, Christmas cactus

45. Walnut Family

46. Female flowers Catkin of male flowers Fruit (a drupe) Young tree Compound leaf Fruit with husk removed to show hard stone (a) The pinnately compound leaves and green fruits of black walnut (Juglans nigra) make the tree easy to recognize. Fig. 25-10a, p. 498

47. Fig. 25-10b, p. 498

48. Fig. 25-10c, p. 498

49. Cactus Family

50. Stamens Stigma Petals (c) Cactus flowers contain numerous sepals, petals, and stamens. The compound pistil consists of two to many fused carpels. In this photo of a prickly pear cactus (Opuntia humifusa), the petals, stamens, and stigma are evident. Fig. 25-11c, p. 499