THE PLANT KINGDOM

1. THE PLANT KINGDOM Chapters29,30, 35,36,37,38,39

2. Figure 29.1 How Plants Colonized Land – Chapter 29-30 • Overview: The Greening of Earth • Looking at a lush landscape It is difficult to imagine the land without any plants or other organisms

3. How Plants Colonized Land

4. Viridiplantae Streptophyta LE 29-4 Plantae Charophyceans Red algae Embryophytes Chlorophytes Ancestral alga

5. Derived Traits of Plants • Five key traits appear in nearly all land plants but are absent in the charophyceans • 1. Apical meristems • 2. Alternation of generations • 3. Walled spores produced in sporangia • 4. Multicellular gametangia • 5. Multicellular dependent embryos • ( + cuticle covering the epidermis for waterproofing)

6. Developing leaves Apical meristem of shoot Apical meristems of plant shoots and roots. The light micrographs are longitudinal sections at the tips of a shoot and root. 1. APICAL MERISTEMS Apical meristem of root Shoot Root 100 µm 100 µm Haploid multicellular organism (gametophyte) Mitosis Mitosis 2. ALTERNATION OF GENERATIONS n n n n n Spores Gametes MEIOSIS FERTILIZATION 2n 2n Zygote Mitosis Diploid multicellular organism (sporophyte) Figure 29.5 Alternation of generations: a generalized scheme Apical meristems and alternation of generations

7. 1. Apical Meristem • Localized regions of cell division at the tips of shoots and roots. • Cells produced by apical meristems differentiate into various tissues, leaves, and roots. • Because plants do not move, they need to elongate to increase exposure to environmental resources.

8. Haploid multicellular organism (gametophyte) Mitosis Mitosis n n n n n Spores Gametes MEIOSIS FERTILIZATION 2n 2n Zygote Mitosis Diploid multicellular organism (sporophyte) Alternation of generations: a generalized scheme 2. Alternation of Generation • Life cycle alternates between two different multicellular bodies.This reproductive cycle is characteristic of land plants

9. Walled spores; multicellular gametangia; and multicellular, dependent embryos Spores 3. WALLED SPORES PRODUCED IN SPORANGIA Protect spores Sporangium Sporophyte and sporangium of Sphagnum (a moss) Longitudinal section of Sphagnum sporangium (LM) Sporophyte Gametophyte 4. MULTICELLULAR GAMETANGIA - Produce Gametes Female gametophyte Archegonium with egg Antheridium with sperm Archegonia ( female )and antheridia (male) of Marchantia (a liverwort) Male gametophyte 5. MULTICELLULAR, DEPENDENT EMBRYOS-embryos Remain in the female parent and receive nutrients from it. Embryo Maternal tissue 2 µm Embryo and placental transfer cell of Marchantia 10 µm Wall ingrowths Figure 29.5 Placental transfer cell

10. Major groups of Plants • Bryophyta – mosses – five derived traits • Pterophyta – Ferns – vascular tissue • Gymnosperm – Conifers – naked seed • Angiosperm – Flowering Plants – Flowers (protected seed) a. Monocots b. Dicots

11. Plant Cladogram: An overview of land plant evolution Land plants Vascular plants Bryophytes (nonvascular plants) Seedless vascular plants Seed plants Mosses Hornworts Liverworts Angiosperms Gymnosperms Charophyceans Pterophyte (ferns, horsetails, whisk fern) Origin of seed plants (about 360 mya) Lycophytes (club mosses, spike mosses, quillworts) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Figure 29.7

12. Bryophyte Gametophytes • In all three bryophyte phyla • Gametophytes are larger and longer-living than sporophytes Gametophyte: Haploid. Produces gametes by mitosis Sporophyte: Diploid – Produces haploid SPORES by meiosis

13. Polytrichum commune, hairy cap moss LE 29-9d Sporophyte Gametophyte

14. Alternation of Generations Haploid multicellular organism (gametophyte) LE 29-5b Mitosis Mitosis Gametes Spores MEIOSIS FERTILIZATION Zygote Mitosis Diploid multicellular organism (sporophyte)

15. Raindrop Key Male gametophyte A sperm swims through a film of moisture to an archegonium and fertilizes the egg. Haploid (n) Spores develop into threadlike protonemata. Sperm Diploid (2n) 5 6 3 8 4 2 1 “Bud” Most mosses have separate male and female gametophytes, with antheridia and archegonia, respectively. Antheridia The haploid protonemata produce “buds” that grow into gametophytes. Protonemata “Bud” Egg Spores Gametophore Femalegametophyte Archegonia Meiosis occurs and haploid spores develop in the sporangium of the sporophyte. When the sporangium lid pops off, the peristome “teeth” regulate gradual release of the spores. Peristome Rhizoid The sporophyte grows a long stalk, or seta, that emerges from the archegonium. Sporangium FERTILIZATION Seta MEIOSIS (within archegonium) Capsule(sporangium) Zygote Calyptra Maturesporophytes Mature sporophytes Embryo Foot Archegonium Youngsporophyte The diploid zygote develops into a sporophyte embryo within the archegonium. Femalegametophytes Capsule with peristome (LM) Attached by its foot, the sporophyte remains nutritionally dependent on the gametophyte. 7 Figure 29.8 • The life cycle of a moss

16. LIVERWORTS (PHYLUM HEPATOPHYTA) Gametophore of female gametophyte Plagiochila deltoidea, a “leafy” liverwort Foot Seta Sporangium Marchantia polymorpha, a “thalloid” liverwort Marchantia sporophyte (LM) 500 µm MOSSES (PHYLUM BRYOPHYTA) HORNWORTS (PHYLUM ANTHOCEROPHYTA) An Anthoceros hornwort species Polytrichum commune, hairy-cap moss Sporophyte Sporophyte Gametophyte Gametophyte Figure 29.9 • Bryophyte diversity

17. Ecological and Economic Importance of Mosses • Sphagnum, or “peat moss” • Forms extensive deposits of partially decayed organic material known as peat • Plays an important role in the Earth’s carbon cycle (a) Peat being harvested from a peat bog Sporangium at tip of sporophyte Gametophyte Living photo- synthetic cells Closeup of Sphagnum. Note the “leafy” gametophytes and their offspring, the sporophytes. (b) Dead water- storing cells 100 µm Sphagnum “leaf” (LM). The combination of living photosynthetic cells and dead water-storing cells gives the moss its spongy quality. (c) (d) “Tolland Man,” a bog mummy dating from 405–100 B.C. The acidic, oxygen-poor conditions produced by Sphagnum canpreserve human or other animal bodies for thousands of years. Figure 29.10 a–d

18. Importance of Peat bogs • Dominant plant is Sphagnum, or peat moss • Absorbs massive amounts of CO2 which is a greenhouse gas • Function as a global thermostat. If the temperature rises, moss grows and pulls more CO2 from the atmosphere. If it cools too much, it releases CO2

19. Ferns and other seedless vascular plants formed the first forests • Bryophytes and bryophyte-like plants • Were the prevalent vegetation during the first 100 million years of plant evolution • Vascular plants • Began to evolve during the Carboniferous period

20. LE 29-14f Athyrium filix-femina, lady fern

21. Key LE 29-12 Haploid (n) Diploid (2n) Antheridium Spore Young gametophyte MEIOSIS Sporangium Sperm Archegonium Egg New sporophyte Mature sporophyte Sporangium Zygote FERTILIZATION Sorus Gametophyte Fiddlehead

22. (a) Sporophyte dependent on gametophyte (mosses and other bryophytes). (b) Large sporophyte and small, independent gametophyte (ferns and other seedless vascular plants). (c) Reduced gametophyte dependent on sporophyte (seed plants: gymnosperms and angiosperms). Gametophyte/sporophyte relationships Sporophyte (2n) Sporophyte (2n) Gametophyte (n) Gametophyte (n) Microscopic female gametophytes (n) in ovulate cones (dependent) Microscopic female gametophytes (n) inside these parts of flowers (dependent) Microscopic male gametophytes (n) inside these parts of flowers (dependent) Microscopic male gametophytes (n) in pollen cones (dependent) Sporophyte (2n), the flowering plant (independent) Sporophyte (2n) (independent) Figure 30.2a–c

23. Vascular plants have two types of vascular tissue • Xylem • Conducts most of the water and minerals • Includes dead cells called tracheids • Phloem • Distributes sugars, amino acids, and other organic products • Consists of living cells

24. Evolution of Roots • Roots • Are organs that anchor vascular plants • Enable vascular plants to absorb water and nutrients from the soil • May have evolved from subterranean stems

25. Evolution of Leaves • Leaves • Are organs that increase the surface area of vascular plants, thereby capturing more solar energy for photosynthesis

26. The life cycle of a fern 1 Sporangia release spores. Most fern species produce a single type of spore that gives rise to a bisexual gametophyte. The fern spore develops into a small, photosynthetic gametophyte. 3 Although this illustration shows an egg and sperm from the same gametophyte, a variety of mechanisms promote cross-fertilization between gametophytes. 2 Key Haploid (n) Diploid (2n) Antheridium Young gametophyte Spore MEIOSIS Sporangium Sperm Archegonium Egg Mature sporophyte New sporophyte Zygote Sporangium FERTILIZATION Sorus On the underside of the sporophyte‘s reproductive leaves are spots called sori. Each sorus is a cluster of sporangia. 6 Fern sperm use flagella to swim from the antheridia to eggs in the archegonia. 4 Gametophyte 5 A zygote develops into a new sporophyte, and the young plant grows out from an archegonium of its parent, the gametophyte. Fiddlehead Figure 29.12

27. Phylum Pterophyta: Ferns, Horsetails, and Whisk Ferns and Relatives • Ferns • Are the most diverse seedless vascular plants

28. The Significance of Seedless Vascular Plants • The ancestors of modern lycophytes, horsetails, and ferns • Grew to great heights during the Carboniferous, forming the first forests

29. Figure 30.1 Importance of Seeds • Overview: Feeding the World • Seeds changed the course of plant evolution • Enabling their bearers to become the dominant producers in most terrestrial ecosystems

30. Integument Spore wall Megasporangium (2n) Megaspore (n) (a) Unfertilized ovule. In this sectional view through the ovule of a pine (a gymnosperm), a fleshy megasporangium is surrounded by a protective layer of tissue called an integument. (Angiosperms have two integuments.) Figure 30.3a Ovules and Production of Eggs • An ovule consists of • A megasporangium, megaspore, and protective integuments

31. Pollen and Production of Sperm • Microspores develop into pollen grains • Which contain the male gametophytes of plants • Pollination • Is the transfer of pollen to the part of a seed plant containing the ovules

32. Importance of Pollen • Pollen, which can be dispersed by air or animals • Eliminated the water requirement for fertilization

33. If a pollen grain germinates • It gives rise to a pollen tube that discharges two sperm into the female gametophyte within the ovule Female gametophyte (n) Egg nucleus (n) Spore wall Male gametophyte (within germinating pollen grain) (n) Discharged sperm nucleus (n) Pollen grain (n) Micropyle (b) Fertilized ovule. A megaspore develops into a multicellular female gametophyte. The micropyle,the only opening through the integument, allowsentry of a pollen grain. The pollen grain contains amale gametophyte, which develops a pollen tubethat discharges sperm. Figure 30.3b

34. Seed coat (derived from Integument) Food supply (female gametophyte tissue) (n) Embryo (2n) (new sporophyte) (c) Gymnosperm seed. Fertilization initiatesthe transformation of the ovule into a seed,which consists of a sporophyte embryo, a food supply, and a protective seed coat derived from the integument. The Evolutionary Advantage of Seeds • A seed • Develops from the whole ovule • Is a sporophyte embryo, along with its food supply, packaged in a protective coat Figure 30.3c

35. Gymnosperms • Gymnosperms bear “naked” seeds, typically on cones • Among the gymnosperms are many well-known conifers • Or cone-bearing trees, including pine, fir, and redwood

36. PHYLUM CYCADOPHYTA PHYLUM GINKGOPHYTA Cycas revoluta PHYLUM GNETOPHYTA Gnetum Welwitschia Ovulate cones Ephedra • Exploring Gymnosperm Diversity Figure 30.4

37. Douglas fir Common juniper Wollemia pine Pacific yew Sequoia Bristlecone pine Exploring Gymnosperm Diversity PHYLUM CYCADOPHYTA Figure 30.4

38. 2 An ovulate cone scale has two ovules, each containing a mega- sporangium. Only one ovule is shown. 1 8 4 5 6 7 3 Key In most conifer species, each tree has both ovulate and pollen cones. Haploid (n) Ovule Diploid (2n) A pollen grain enters through the micropyle and germinates, forming a pollen tube that slowly digests through the megasporangium. Megasporocyte (2n) Ovulate cone Integument Longitudinal section of ovulate cone Micropyle Pollen cone Microsporocytes (2n) Megasporangium Mature sporophyte (2n) Germinating pollen grain Pollen grains (n) (containing male gametophytes) MEIOSIS MEIOSIS While the pollen tube develops, the megasporocyte (megaspore mother cell) undergoes meiosis, producing four haploid cells. One survives as a megaspore. Longitudinal section of pollen cone Surviving megaspore (n) Sporophyll Microsporangium A pollen cone contains many microsporangia held in sporophylls. Each microsporangium contains microsporocytes (microspore mother cells). These undergo meiosis, giving rise to haploid microspores that develop into pollen grains. Seedling Germinating pollen grain Archegonium Egg (n) Integument Female gametophyte Seeds on surface of ovulate scale Germinating pollen grain (n) Food reserves (gametophyte tissue) (n) The female gametophyte develops within the megaspore and contains two or three archegonia, each with an egg. Seed coat (derived from parent sporophyte) (2n) Fertilization usually occurs more than a year after pollination. All eggs may be fertilized, but usually only one zygote develops into an embryo. The ovule becomes a seed, consisting of an embryo, food supply, and seed coat. Discharged sperm nucleus (n) Pollen tube By the time the eggs are mature, two sperm cells have developed in the pollen tube, which extends to the female gametophyte. Fertilization occurs when sperm and egg nuclei unite. Embryo (new sporophyte) (2n) FERTILIZATION Egg nucleus (n) Figure 30.6 The life cycle of a pine

39. Angiosperms • The reproductive adaptations of angiosperms include flowers and fruits • Angiosperms • Are commonly known as flowering plants • Are seed plants that produce the reproductive structures called flowers and fruits • Are the most widespread and diverse of all plants

40. Characteristics of Angiosperms • The key adaptations in the evolution of angiosperms • Are flowers and fruits

41. Carpel Stigma Anther Style Stamen Ovary Filament Petal Sepal Receptacle Ovule Flower – reproductive structure of an angiosperm • A flower is a specialized shoot with modified leaves • Sepals, which enclose the flower • Petals, which are brightly colored and attract pollinators • Stamens, which produce pollen • Carpels, which produce ovules Figure 30.7

42. (b) Ruby grapefruit, a fleshy fruitwith a hard outer layer andsoft inner layer of pericarp (a) Tomato, a fleshy fruit withsoft outer and inner layersof pericarp (c) Nectarine, a fleshyfruit with a soft outerlayer and hard innerlayer (pit) of pericarp (d) Milkweed, a dry fruit thatsplits open at maturity (e) Walnut, a dry fruit that remains closed at maturity Figure 30.8a–e Fruits - Typically consist of a mature ovary

43. (a) Wings enable maple fruits to be easily carried by the wind. (b) Seeds within berries and other edible fruits are often dispersed in animal feces. (c) The barbs of cockleburs facilitate seed dispersal by allowing the fruits to “hitchhike” on animals. Can be carried by wind, water, or animals to new locations, enhancing seed dispersal Figure 30.9a–c

44. The Angiosperm Life Cycle • In the angiosperm life cycle • Double fertilization occurs when a pollen tube discharges two sperm into the female gametophyte within an ovule • One sperm fertilizes the egg, while the other combines with two nuclei in the center cell of the female gametophyte and initiates development of food-storing endosperm • The endosperm • Nourishes the developing embryo

45. Angiosperm Diversity • The two main groups of angiosperms • Are monocots and eudicots (Dicots

46. BASAL ANGIOSPERMS Amborella trichopoda Star anise (Illicium floridanum) Water lily (Nymphaea “Rene Gerard”) HYPOTHETICAL TREE OF FLOWERING PLANTS Monocots Eudicots Star anise and relatives Water lilies Amborella Magnoliids MAGNOLIIDS Southern magnolia (Magnolia grandiflora) Exploring Angiosperm Diversity Figure 30.12

47. EUDICOTS MONOCOTS Monocot Characteristics Eudicot Characteristics California poppy (Eschscholzia californica) Orchid (Lemboglossum fossii) Embryos One cotyledon Two cotyledons Leaf venation Pyrenean oak (Quercus pyrenaica) Veins usually netlike Veins usually parallel Pygmy date palm (Phoenix roebelenii) Stems Vascular tissue usually arranged in ring Lily (Lilium “Enchant- ment”) Vascular tissue scattered Roots Dog rose (Rosa canina), a wild rose Root system Usually fibrous (no main root) Taproot (main root) usually present Barley (Hordeum vulgare), a grass Pea (Lathyrus nervosus, Lord Anson’sblue pea), a legume Pollen Pollen grain with three openings Pollen grain with one opening Flowers Zucchini (Cucurbita Pepo), female (left) andmale flowers Anther Floral organs usually in multiples of three Floral organs usually in multiples of four or five Stigma Filament Ovary Exploring Angiosperm Diversity Figure 30.12

48. (c) A flower pollinated by nocturnal animals. Some angiosperms, such as this cactus, depend mainly on nocturnal pollinators, including bats. Common adaptations of such plants include large, light-colored, highly fragrant flowers that nighttime pollinators can locate. (a) A flower pollinated by honeybees. This honeybee is harvesting pollen and nectar (a sugary solution secreted by flower glands) from a Scottish broom flower. The flower has a tripping mechanism that arches the stamens over the beeand dusts it with pollen, some ofwhich will rub off onto the stigmaof the next flower the bee visits. (b) A flower pollinated by hummingbirds.The long, thin beak and tongue of this rufous hummingbird enable the animal to probe flowers that secrete nectar deep within floral tubes. Before the hummer leaves, anthers will dust its beak and head feathers with pollen. Many flowers that are pollinated by birds are red or pink, colors to which bird eyes are especially sensitive. Evolutionary Links Between Angiosperms and Animals • Pollination of flowers by animals and transport of seeds by animals • Are two important relationships in terrestrial ecosystems Figure 30.13a–c

49. Human welfare depends greatly on seed plants • No group is more important to human survival than seed plants

50. Products from Seed Plants • Humans depend on seed plants for • Food • Wood • Many medicines Table 30.1