1. Plant Diversity II: The Evolution of Seed Plants Adapted for Union City High School by Greg Campbell From Campbell, N. and Reece, J. (2008). Biology 8 th Ed. San Francisco, Ca. Pearson Benjamin Cummings.

2. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Seeds changed the course of plant evolution, enabling their bearers to become the dominant producers in most ____________ecosystems  A ______consists of an embryo and nutrients surrounded by a protective coat

3. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  In addition to seeds, the following are common to all seed plants 1.____________________ 2.____________________ 3.____________________ 4.____________________

4. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  The ____________of seed plants develop within the walls of spores that are retained within tissues of the parent ____________

5. Fig. 30-2 Reduced (usually microscopic), dependent on surrounding sporophyte tissue for nutrition Reduced, independent (photosynthetic and free-living) Gametophyte Sporophyte (2n) Gametophyte (n) Sporophyte Example Gametophyte (n) Dominant Reduced, dependent on gametophyte for nutrition Mosses and other nonvascular plants Ferns and other seedless vascular plants Seed plants (gymnosperms and angiosperms) PLANT GROUP GymnospermAngiosperm Microscopic female gametophytes (n) inside ovulate cone Microscopic male gametophytes (n) inside pollen cone Sporophyte (2n) Microscopic female gametophytes (n) inside these parts of flowers Microscopic male gametophytes (n) inside these parts of flowers

6. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  The ancestors of seed plants were likely _____________, while seed plants are heterosporous  _________________produce megaspores that give rise to _________ gametophytes  _________________produce microspores that give rise to _______ gametophytes

7. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  An _________ consists of a megasporangium, megaspore, and one or more protective _______________  ________________ megaspores have one integument  _______________ megaspores usually have two integuments

8. Fig. 30-3-1 Megasporangium (2n) Megaspore (n) (a) Unfertilized ovule Integument Spore wall Immature female cone

9. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Microspores develop into pollen grains, which contain the _________ gametophytes  _____________ is the transfer of pollen to the part of a seed plant containing the ovules  Pollen eliminates the need for ___________ and can be dispersed great distances by air or ___________  If a pollen grain germinates, it gives rise to a pollen ______ that discharges two _____ into the female gametophyte within the ovule

10. Fig. 30-3-2 Male gametophyte (within a germinated pollen grain) (n) Female gametophyte (n) (b) Fertilized ovule Micropyle Pollen grain (n) Spore wall Discharged sperm nucleus (n) Egg nucleus (n)

11. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  A seed develops from the whole ovule  A seed is a ___________ embryo, along with its food supply, packaged in a protective coat  Seeds provide some evolutionary advantages over spores: 1.____________________________________ 2.____________________________________

12. Fig. 30-3-4 Seed coat (derived from integument) (c) Gymnosperm seed Embryo (2n) (new sporophyte) Food supply (female gametophyte tissue) (n) (b) Fertilized ovule(a) Unfertilized ovule Integument Immature female cone Spore wall Megasporangium (2n) Male gametophyte (within a germinated pollen grain) (n) Megaspore (n) MicropylePollen grain (n) Egg nucleus (n) Discharged sperm nucleus (n) Female gametophyte (n)

13. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  The gymnosperms have “naked” seeds not enclosed by ovaries and consist of four phyla: ◦ Cycadophyta (cycads) ◦ Gingkophyta (one living species: Ginkgo biloba) ◦ Gnetophyta (three genera: Gnetum, Ephedra, Welwitschia) ◦ Coniferophyta (conifers, such as pine, fir, and redwood)

14. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Living seed plants can be divided into two clades: gymnosperms and angiosperms  Gymnosperms appear early in the fossil record and dominated the Mesozoic terrestrial ecosystems  Gymnosperms were better suited than nonvascular plants to drier conditions  Today, cone-bearing gymnosperms called conifers dominate in the northern latitudes

15. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Individuals have large cones and palmlike leaves These thrived during the Mesozoic, but relatively few species exist today This phylum consists of a single living species, Ginkgo biloba It has a high tolerance to air pollution and is a popular ornamental tree

16. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings This phylum comprises three genera Species vary in appearance, and some are tropical whereas others live in deserts This phylum is by far the largest of the gymnosperm phyla Most conifers are evergreens and can carry out photosynthesis year round

17. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Three key features of the gymnosperm life cycle are: ◦ Dominance of the ____________ generation ◦ Development of _______ from fertilized ovules ◦ The transfer of sperm to ovules by _________  The life cycle of a pine provides an example Animation: Pine Life Cycle Animation: Pine Life Cycle

18. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  The pine tree is the __________ and produces sporangia in male and female cones  Small cones produce microspores called pollen grains, each of which contains a male _____________  The familiar larger cones contain ______, which produce megaspores that develop into female ______________  It takes nearly three years from cone production to mature seed

19. Fig. 30-6-4 Microsporangium (2n) Microsporocytes (2n) Pollen grains (n) Pollen cone Microsporangia MEIOSIS Mature sporophyte (2n) Haploid (n) Diploid (2n) Key MEIOSIS Surviving megaspore (n) Pollen grain Megasporocyte (2n) Ovule Integument Ovulate cone FERTILIZATION Pollen tube Female gametophyte Sperm nucleus (n) Egg nucleus (n) Archegonium Seedling Seeds Seed coat (2n) Food reserves (n) Embryo (2n) Megasporangium (2n)

20. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  ____________ are seed plants with reproductive structures called flowers and fruits  They are the most widespread and diverse of all plants

21. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  All angiosperms are classified in a single phylum, ____________.  The name comes from the Greek anthos, flower

22. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  The _________ is an angiosperm structure specialized for sexual reproduction  Many species are pollinated by insects or animals, while some species are wind- pollinated

23. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  A flower is a specialized shoot with up to four types of modified leaves: ◦ ______, which enclose the flower ◦ ______, which are brightly colored and attract pollinators ◦ ________, which produce pollen on their terminal anthers ◦ ________, which produce ovules

24. Fig. 30-7 Carpel Ovule Sepal Petal Stigma Style Ovary Stamen Anther Filament

25. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  A carpel consists of an ______ at the base and a style leading up to a _______, where pollen is received Video: Flower Blooming (time lapse) Video: Flower Blooming (time lapse)

26. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  A fruit typically consists of a mature ovary but can also include other flower parts  Fruits protect seeds and aid in their dispersal  Mature fruits can be either fleshy or dry Animation: Fruit Development Animation: Fruit Development

27. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Various fruit adaptations help disperse seeds  Seeds can be carried by wind, water, or animals to new locations

28. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The flower of the sporophyte is composed of both male and female structures Male gametophytes are contained within pollen grains produced by the _____________ of anthers The female gametophyte, or embryo sac, develops within an ovule contained within an ________ at the base of a stigma Most flowers have mechanisms to ensure cross-pollination between flowers from different plants of the same species

29. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A pollen grain that has landed on a stigma germinates and the ______________ of the male gametophyte grows down to the ovary The ovule is entered by a pore called the ___________ ______________________ occurs when the pollen tube discharges two sperm into the female gametophyte within an ovule

30. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings One sperm fertilizes the egg, while the other combines with two nuclei in the central cell of the female gametophyte and initiates development of food-storing _____________ The endosperm nourishes the developing _________ Within a seed, the embryo consists of a root and two seed leaves called _______________

31. Fig. 30-10-4 MEIOSIS Key Microsporangium Microsporocytes (2n) Generative cell Anther Tube cell Pollen grains Microspore (n) Male gametophyte (in pollen grain) (n) Mature flower on sporophyte plant (2n) Haploid (n) Diploid (2n) MEIOSIS Ovule (2n) Ovary Megasporangium (2n) Megaspore (n) Female gametophyte (embryo sac) Antipodal cells Central cell Synergids Egg (n) Pollen tube Stigma Sperm (n) Discharged sperm nuclei (n) FERTILIZATION Germinating seed Embryo (2n) Endosperm (3n) Seed coat (2n) Seed Nucleus of developing endosperm (3n) Zygote (2n) Egg nucleus (n) Style Sperm

32. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Clarifying the origin and diversification of angiosperms poses fascinating challenges to evolutionary biologists  Angiosperms originated at least 140 million years ago  During the late Mesozoic, the major branches of the clade diverged from their common ancestor

33. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  The ancestors of angiosperms and gymnosperms diverged about 305 million years ago  Angiosperms may be closely related to Bennettitales, extinct seed plants with flowerlike structures  Amborella and water lilies are likely descended from two of the most ancient angiosperm lineages

34. Fig. 30-12 Microsporangia (contain microspores) Ovules A possible ancestor of the angiosperms? (a) (b) Angiosperm phylogeny Most recent common ancestor of all living angiosperms Millions of years ago 300 250 200 150 100 50 0 Living gymnosperms Bennettitales Amborella Star anise and relatives Water lilies Monocots Magnoliids Eudicots

35. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  The two main groups of angiosperms are ____________(one cotyledon) and _________ (“true” dicots)  The clade eudicot includes some groups formerly assigned to the paraphyletic dicot (two cotyledons) group

36. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings More than one-quarter of angiosperm species are monocots More than two-thirds of angiosperm species are eudicots

37. Fig. 30-13o Roots Pollen Root system usually fibrous (no main root) Pollen grain with three openings Pollen grain with one opening Floral organs usually in multiples of three Flowers Floral organs usually in multiples of four or five Monocot Characteristics Eudicot Characteristics Taproot (main root) usually present Monocot Characteristics Eudicot Characteristics Vascular tissue usually arranged in ring Veins usually parallel Vascular tissue scattered Leaf venation One cotyledon Embryos Two cotyledons Stems Veins usually netlike

38. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Pollination of flowers and transport of seeds by animals are two important relationships in terrestrial ecosystems  Clades with bilaterally symmetrical flowers have more species than those with radially symmetrical flowers  This is likely because bilateral symmetry affects the movement of pollinators and reduces gene flow in diverging populations Video: Bat Pollinating Agave Plant Video: Bat Pollinating Agave Plant Video: Bee Pollinating Video: Bee Pollinating

39. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  No group of plants is more important to human survival than seed plants  Plants are key sources of food, fuel, wood products, and medicine  Our reliance on seed plants makes preservation of plant diversity critical

40. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Most of our food comes from angiosperms  Six crops (wheat, rice, maize, potatoes, cassava, and sweet potatoes) yield 80% of the calories consumed by humans  Modern crops are products of relatively recent genetic change resulting from artificial selection  Many seed plants provide wood  Secondary compounds of seed plants are used in medicines

41. Table 30-1a

42. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings  Destruction of habitat is causing extinction of many plant species  Loss of plant habitat is often accompanied by loss of the animal species that plants support  At the current rate of habitat loss, 50% of Earth’s species will become extinct within the next 100–200 years