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Chapter 30 Plant Diversity II. Fig. 29-7 Origin of land plants (about 475 mya) 1 2 3 1 2 3 Origin of vascular plants (about 420 mya) Origin of extant.

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Presentation on theme: "Chapter 30 Plant Diversity II. Fig. 29-7 Origin of land plants (about 475 mya) 1 2 3 1 2 3 Origin of vascular plants (about 420 mya) Origin of extant."— Presentation transcript:

1 Chapter 30 Plant Diversity II

2 Fig Origin of land plants (about 475 mya) Origin of vascular plants (about 420 mya) Origin of extant seed plants (about 305 mya) ANCES- TRAL GREEN ALGA Liverworts Hornworts Mosses Lycophytes (club mosses, spike mosses, quillworts) Pterophytes (ferns, horsetails, whisk ferns) Gymnosperms Angiosperms Seed plants Seedless vascular plants Nonvascular plants (bryophytes) Land plants Vascular plants Millions of years ago (mya) Chapter 30: Plant Diversity II

3 What are five crucial adaptations that led the success of seed Plants? –Seeds –Reduced gametophytes –Heterospory –Ovules –Pollen

4 Seeds Seeds changed the course of plant evolution, enabling their bearers to become the dominant producers in most terrestrial ecosystems A seed consists of an embryo and nutrients surrounded by a protective coat

5 Fig 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 Reduced Gametophyte Reduced Gametophyte : protection of antheridia and archegonia

6 Heterospory: The Rule Among Seed Plants The ancestors of seed plants were likely homosporous, while seed plants are heterosporous Megasporangia produce megaspores that give rise to female gametophytes Microsporangia produce microspores that give rise to male gametophytes

7 Ovules and Production of Eggs An ovule consists of a megasporang ium, megaspore, and one or more protective integuments Megasporangium (2n) Megaspore (n) (a) Unfertilized ovule Integument Spore wall Immature female cone

8 Pollen and Production of Sperm Microspores develop into pollen grains, which contain the male gametophytes Pollination Pollen eliminates the need for a film of water and can be dispersed great distances by air or animals If a pollen grain germinates, it gives rise to a pollen tube that discharges two sperm into the female gametophyte within the ovule 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)

9 The Evolutionary Advantage of Seeds A seed develops from the whole ovule A seed is a sporophyte embryo, along with its food supply, packaged in a protective coat Seeds provide some evolutionary advantages over spores: –They may remain dormant for days to years, until conditions are favorable for germination –They may be transported long distances by wind or animals

10 Fig. 30-UN1 Nonvascular plants (bryophytes) Seedless vascular plants Gymnosperms Angiosperms Gymnosperms What are the four phyla of gymnosperms? Which phyla is the most biologically significant?

11 Concept 30.2: Gymnosperms bear “naked” seeds, typically on cones 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)

12 Phylum Cycadophyta Individuals have large cones and palmlike leaves These thrived during the Mesozoic, but relatively few species exist today

13 Fig. 30-5a Cycas revoluta

14 Phylum Ginkgophyta This phylum consists of a single living species, Ginkgo biloba It has a high tolerance to air pollution and is a popular ornamental tree

15 Fig. 30-5b Ginkgo biloba pollen-producing tree

16 Fig. 30-5c Ginkgo biloba leaves and fleshy seeds

17 Phylum Gnetophyta This phylum comprises three genera Species vary in appearance, and some are tropical whereas others live in deserts

18 Fig. 30-5e Ephedra

19 Fig. 30-5f Welwitschia

20 Fig. 30-5g Welwitschia Ovulate cones

21 Phylum Coniferophyta This phylum is by far the largest of the gymnosperm phyla Most conifers are evergreens and can carry out photosynthesis year round

22 Fig. 30-5i European larch

23 Fig. 30-5j Bristlecone pine

24 Fig. 30-5k Sequoia

25 Fig. 30-5m Common juniper

26 The Life Cycle of a Pine: A Closer Look Three key features of the gymnosperm life cycle are: –Dominance of the sporophyte generation –Development of seeds from fertilized ovules –The transfer of sperm to ovules by pollen The life cycle of a pine provides an example Animation: Pine Life Cycle Animation: Pine Life Cycle

27 Fig 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)

28 Angiosperms Angiosperms are seed plants with reproductive structures called flowers and fruits They are the most widespread and diverse of all plants Nonvascular plants (bryophytes) Seedless vascular plants Gymnosperms Angiosperms

29 Fig Carpel Ovule Sepal Petal Stigma Style Ovary Stamen Anther Filament Video: Flower Blooming (time lapse) Video: Flower Blooming (time lapse)

30 Fruits 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

31 Fig Hazelnut Ruby grapefruit Tomato Nectarine Milkweed

32 Fig Barbs Seeds within berries Wings

33 The Angiosperm Life Cycle The flower of the sporophyte is composed of both male and female structures Male gametophytes are contained within pollen grains produced by the microsporangia of anthers The female gametophyte, or embryo sac, develops within an ovule contained within an ovary at the base of a stigma Most flowers have mechanisms to ensure cross-pollination between flowers from different plants of the same species

34 A pollen grain that has landed on a stigma germinates and the pollen tube of the male gametophyte grows down to the ovary The ovule is entered by a pore called the micropyle Double fertilization occurs when the pollen tube discharges two sperm into the female gametophyte within an ovule

35 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 endosperm The endosperm nourishes the developing embryo Within a seed, the embryo consists of a root and two seed leaves called cotyledons

36 Fig 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

37 Video: Flowering Plant Life Cycle (time lapse) Video: Flowering Plant Life Cycle (time lapse) Animation: Seed Development Animation: Seed Development Animation: Plant Fertilization Animation: Plant Fertilization

38 Fig n 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

39 Fig o 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

40 Basal Angiosperms Three small lineages constitute the basal angiosperms These include Amborella trichopoda, water lilies, and star anise

41 Fig b Water lily

42 Fig c Star anise

43 Magnoliids Magnoliids include magnolias, laurels, and black pepper plants Magnoliids are more closely related to monocots and eudicots than basal angiosperms

44 Fig d Southern magnolia

45 Monocots More than one-quarter of angiosperm species are monocots

46 Fig e Orchid

47 Fig f

48 Fig g Anther Barley Stigma Ovary Filament

49 Eudicots More than two-thirds of angiosperm species are eudicots

50 Fig h California poppy

51 Fig j Dog rose

52 Fig l Zucchini flowers


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