Chapter 29 Plant Diversity 1.What are the characteristics of plants? -Photosynthetic autotrophs -Cellulose in cell walls -Starch as storage polysaccharide -PROBLEM – light, CO 2 & O 2 are above ground - water & minerals are below ground -SOLUTION – evolution of specialized structures 2.What adaptations do plants have for survival on land? -Stomata – pores used for gas exchange -Roots – absorb water & minerals from underground -Apical meristems – tips of shoots & roots where growth occurs -Cuticle – waxy covering to prevent water loss thru leaves -Jacketed gametangia – gamete producing organ with protective jacket of cells to prevent dehydration -Sporopollenin – polymer that formed around exposed zygotes & forms walls of plant spores preventing dehydration -Lignin – structural polymer that provides strength for woody tissues of vascular plants Algae also

Chapter 29: Plant Diversity 1.What are the characteristics of plants? 2.What adaptations do plants have for survival on land? 3. What were the adaptations/highlights of plant evolution? -Plants likely evolved from Charophytes (green algae) -similar peroxisome enzymes -similar %age of cellulose found in plants & charophytes -nuclear & chloroplast genes have similar DNA -Movement to land led to Bryophytes (mosses & worts) -Tougher spores (sporopollenin) -Jacketed gametangia -Vascular tissue (ferns) -Cells joined to transport water & nutrients -Lacked seeds -Development of seeds (Gymnosperms, e.g. pine tree) -More protection of embryo -Embryo w/ food -Development of flowers (Angiosperms, e.g. oak tree) -Complex reproductive structure

Figure 29.7 Highlights of plant evolution Bryophytes (nonvascular plants) Seedless vascular plants Seed plants Vascular plants Land plants Origin of seed plants (about 360 mya) Origin of vascular plants (about 420 mya) Origin of land plants (about 475 mya) Ancestral green alga Charophyceans Liverworts Hornworts Mosses Lycophytes (club mosses, spike mosses, quillworts) Pterophytes (ferns, horsetails, whisk ferns) Gymnosperms Angiosperms

Chapter 29 Plant Diversity 1.What are the characteristics of plants? 2.What adaptations do plants have for survival on land? 3. What were the adaptations/highlights of plant evolution? 4. Describe alternation of generations -Alternates between sexual & asexual reproduction -Gametophyte (n) make gametes by mitosis -Sporophyte (2n) makes spores by meiosis Haploid multicellular organism (gametophyte) Mitosis Gametes Zygote Diploid multicellular organism (sporophyte) Alternation of generations: a generalized scheme MEIOSISFERTILIZATION 2n2n 2n2n n n n n n Spores Mitosis

Figure 29.8 The life cycle of a Polytrichum moss Mature sporophytes Young sporophytes Male gametophyte Raindrop Sperm Key Haploid (n) Diploid (2n) Antheridia Female gametophyte Egg Arch- egonia FERTILIZATION (within archegonium) Zygote Archegonium Embryo Female gametophytes Gametophore Foot Capsule (sporangium) Seta Peristome Spores Protonemata “Bud” MEIOSIS Sporangium Calyptra Capsule with peristome (LM) Rhizoid Mature sporophytes

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

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

Figure Seedless Vascular Plant Diversity LYCOPHYTES (PHYLUM LYCOPHYTA) PTEROPHYTES (PHYLUM PTEROPHYTA) WHISK FERNS AND RELATIVES HORSETAILS FERNS Isoetes gunnii, a quillwort Selaginella apoda, a spike moss Diphasiastrum tristachyum, a club moss Strobili (clusters of sporophylls) Psilotum nudum, a whisk fern Equisetum arvense, field horsetail Vegetative stem Strobilus on fertile stem Athyrium filix-femina, lady fern

Chapter 30: The Evolution of Seed Plants 1.What are the 3 most important reproductive adaptations? -Reduction of the gametophyte -Advent of the seed – replaced spore -Evolution of pollen – male gametophyte -Air dispersal instead of sperm swimming

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

Chapter 30: The Evolution of Seed Plants 1.What are the 3 most important reproductive adaptations? -Reduction of the gametophyte -Advent of the seed – replaced spore as -Evolution of pollen – male gametophyte 2.How does an ovule become a seed? -Fertilization -Growth of the embryo

Figure 30.3 From ovule to seed 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.) (a) Fertilized ovule. A megaspore develops into a multicellular female gametophyte. The micropyle, the only opening through the integument, allows entry of a pollen grain. The pollen grain contains a male gametophyte, which develops a pollen tube that discharges sperm. (b) Gymnosperm seed. Fertilization initiates the 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. (c) Integument Spore wall Megasporangium (2n) Megaspore (n) Male gametophyte (within germinating pollen grain) (n) Female gametophyte (n) Egg nucleus (n) Discharged sperm nucleus (n) Pollen grain (n) Micropyle Seed coat (derived from integument) Food supply (female gametophyte tissue) (n) Embryo (2n) (new sporophyte)

Chapter 30: The Evolution of Seed Plants 1.What are the 3 most important reproductive adaptations? 2.How does an ovule become a seed? 3.What’s the difference between a megaspore & a microspore? -Megasporangia  megaspores  female gametophytes (eggs) -Microsporangia  microspores  male gametophytes (sperm) 4.What are gymnosperms? -“naked seed” plants -Pines, spruce, fir, sequoia, yews, junipers, ginkgo -Most lumber & paper products -The gymnosperm life cycle…

Figure 30.6 The life cycle of a pine FERTILIZATION Seed coat (derived from parent sporophyte) (2n) Food reserves (gametophyte tissue) (n) Embryo (new sporophyte) (2n) Seeds on surface of ovulate scale Seedling MEIOSIS Surviving megaspore (n) Germinating pollen grain Archegonium IntegumentEgg (n) Female gametophyte Germinating pollen grain (n) Discharged sperm nucleus (n) Pollen tube Egg nucleus (n) Ovule Key Haploid (n) Diploid (2n) Megasporocyte (2n) Integument Longitudinal section of ovulate cone Ovulate cone Pollen cone Mature sporophyte (2n) Longitudinal section of pollen cone Microsporocytes (2n) Pollen grains (n) (containing male gametophytes) Micropyle Germinating pollen grain Megasporangium MEIOSIS Sporophyll Microsporangium

Chapter 30: The Evolution of Seed Plants 1.What are the 3 most important reproductive adaptations? 2.How does an ovule become a seed? 3.What’s the difference between a megaspore & a microspore? 4.What are gymnosperms? -“naked seed” plants -Pines, spruce, fir, sequoia, yews, junipers, ginkgo -Most lumber & paper products -The gymnosperm life cycle… 5.What are angiosperms? - Flowering plants 6.What is a flower? - Reproductive structure of an angiosperm

Figure 30.7 The structure of an idealized flower Anther Filament Stigma Style Ovary Carpel Petal Receptacle Ovule Sepal Stamen Female structures Male structures

Chapter 30: The Evolution of Seed Plants 1.What are the 3 most important reproductive adaptations? 2.How does an ovule become a seed? 3.What’s the difference between a megaspore & a microspore? 4.What are gymnosperms? 5.What are angiosperms? 6.What is a flower? -Reproductive structure of an angiosperm 7.What is a fruit? -Mature ovary -Helps seed dispersal

Figure 30.8 Some variations in fruit structure Ruby grapefruit, a fleshy fruit with a hard outer layer and soft inner layer of pericarp (b) Tomato, a fleshy fruit with soft outer and inner layers of pericarp (a) Nectarine, a fleshy fruit with a soft outer layer and hard inner layer (pit) of pericarp (c) Walnut, a dry fruit that remains closed at maturity (e) (d) Milkweed, a dry fruit that splits open at maturity

Figure 30.9 Fruit adaptations that enhance seed dispersal Wings enable maple fruits to be easily carried by the wind. (a) Seeds within berries and other edible fruits are often dispersed in animal feces. (b) The barbs of cockleburs facilitate seed dispersal by allowing the fruits to “hitchhike” on animals. (c)

Chapter 30: The Evolution of Seed Plants 1.What are the 3 most important reproductive adaptations? 2.How does an ovule become a seed? 3.What’s the difference between a megaspore & a microspore? 4.What are gymnosperms? 5.What are angiosperms? 6.What is a flower? 7.What is a fruit? 8.The angiosperm life cycle….

Figure The life cycle of an angiosperm Nucleus of developing endosperm (3n) Zygote (2n) FERTILIZATION Embryo (2n) Endosperm (food supply) (3n) Seed coat (2n) Seed Germinating seed Pollen tube Sperm Stigma Pollen grains Pollen tube Style Discharged sperm nuclei (n) Egg nucleus (n) Mature flower on sporophyte plant (2n) Key Haploid (n) Diploid (2n) Anther Ovule with megasporangium (2n) Male gametophyte (in pollen grain) Microspore (n) MEIOSIS Microsporangium Microsporocytes (2n) MEIOSIS Generative cell Tube cell Surviving megaspore (n) Ovary Megasporangium (n) Female gametophyte (embryo sac) Antipodal cells Polar nuclei Synergids Egg (n) Pollen tube Sperm (n) Double fertilization

Chapter 30: The Evolution of Seed Plants 1.What are the 3 most important reproductive adaptations? 2.How does an ovule become a seed? 3.What’s the difference between a megaspore & a microspore? 4.What are gymnosperms? 5.What are angiosperms? 6.What is a flower? 7.What is a fruit? 8.The angiosperm life cycle…. 9.Why is double fertilization important? -Synchronizes food development with embryo development -Prevents angiosperms from wasting nutrients on unfertilized ovules 10. What are the 2 general types of angiosperms? -Monocots -Eudicots

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

Table 29.1 Ten Phyla of Extant Plants