What human reproductive organ is functionally similar to this seed? Figure 30.1 What human reproductive organ is functionally similar to this seed?

Gametophyte / sporophyte relationships in different plant groups Mosses and other nonvascular plants Ferns and other seedless vascular plants Seed plants (gymnosperms and angiosperms) Reduced, independent (photosynthetic and free-living) Reduced (usually microscopic), dependent on surrounding sporophyte tissue for nutrition Gametophyte Dominant Sporophyte Reduced, dependent on gametophyte for nutrition Dominant Dominant Gymnosperm Angiosperm Sporophyte (2n) Microscopic female gametophytes (n) inside ovulate cone Microscopic female gametophytes (n) inside these parts of flowers Sporophyte (2n) Gametophyte (n) Example Figure 30.2 Gametophyte/sporophyte relationships in different plant groups Microscopic male gametophytes (n) inside these parts of flowers Microscopic male gametophytes (n) inside pollen cone Sporophyte (2n) Sporophyte (2n) Gametophyte (n)

(a) Unfertilized ovule From ovule to seed in a gymnosperm Integument Spore wall Immature female cone Megasporangium (2n) Figure 30.3a From ovule to seed in a gymnosperm Megaspore (n) (a) Unfertilized ovule

Female gametophyte (n) From ovule to seed in a gymnosperm Female gametophyte (n) Spore wall Egg nucleus (n) Male gametophyte (within a germinated pollen grain) (n) Discharged sperm nucleus (n) Figure 30.3b From ovule to seed in a gymnosperm Micropyle Pollen grain (n) (b) Fertilized ovule

Seed coat (derived from integument) From ovule to seed in a gymnosperm Seed coat (derived from integument) Food supply (female gametophyte tissue) (n) Figure 30.3c From ovule to seed in a gymnosperm Embryo (2n) (new sporophyte) (c) Gymnosperm seed

From ovule to seed in a gymnosperm Seed coat (derived from integument) Integument Female gametophyte (n) Spore wall Egg nucleus (n) Immature female cone Food supply (female gametophyte tissue) (n) Male gametophyte (within a germinated pollen grain) (n) Megasporangium (2n) Discharged sperm nucleus (n) Embryo (2n) (new sporophyte) Megaspore (n) Micropyle Pollen grain (n) Figure 30.3 From ovule to seed in a gymnosperm (a) Unfertilized ovule (b) Fertilized ovule (c) Gymnosperm seed

Ginkgo biloba Pollen-producing tree with fleshy seeds Gymnosperm Figure 30.5 Gymnosperm diversity Ginkgo biloba Pollen-producing tree with fleshy seeds

Gymnosperm Ovulate cones Figure 30.5 Gymnosperm diversity Welwitschia

Gymnosperms: Conifers perform year round photosynthesis Figure 30.5 Gymnosperm diversity Douglas fir

Giant Sequoia: 2,500 tons / 1,800 - 2,700 years old Gymnosperms: Conifers Sequoia - One of the Largest and Oldest Living Organisms Figure 30.5 Gymnosperm diversity Giant Sequoia: 2,500 tons / 1,800 - 2,700 years old

Life Cycle of a Pine Key Haploid (n) Ovule Diploid (2n) Ovulate cone Megasporocyte (2n) Integument Pollen cone Microsporocytes (2n) Mature sporophyte (2n) Megasporangium (2n) Pollen grain Pollen grains (n) MEIOSIS MEIOSIS Microsporangia Microsporangium (2n) Surviving megaspore (n) Seedling Archegonium Figure 30.6 The life cycle of a pine Seeds Female gametophyte Food reserves (n) Sperm nucleus (n) Seed coat (2n) Pollen tube Embryo (2n) FERTILIZATION Egg nucleus (n)

Stigma Carpel Stamen Anther Style Filament Ovary Petal Sepal Ovule Structure of an Idealized Flower Stigma Carpel Stamen Anther Style Filament Ovary Figure 30.7 The structure of an idealized flower Petal Sepal Ovule

Tomato Ruby grapefruit Nectarine Hazelnut Milkweed Fruits Figure 30.8 Some variations in fruit structure Hazelnut Milkweed

Wings Seeds within berries Barbs Fruit Adaptations for Seed Dispersal Figure 30.9 Fruit adaptations that enhance seed dispersal Barbs

Life Cycle of an Angiosperm Key Haploid (n) Diploid (2n) Microsporangium Anther Mature flower on sporophyte plant (2n) Microsporocytes (2n) MEIOSIS Generative cell Microspore (n) Ovule (2n) Tube cell Male gametophyte (in pollen grain) (n) Ovary Pollen grains MEIOSIS Germinating seed Stigma Megasporangium (2n) Pollen tube Embryo (2n) Endosperm (3n) Seed coat (2n) Sperm Seed Megaspore (n) Style Antipodal cells Central cell Synergids Egg (n) Figure 30.10 The life cycle of an angiosperm Female gametophyte (embryo sac) Pollen tube Sperm (n) Nucleus of developing endosperm (3n) FERTILIZATION Zygote (2n) Egg nucleus (n) Discharged sperm nuclei (n)

Angiosperm evolutionary history Living gymnosperms Microsporangia (contain microspores) Bennettitales Amborella Water lilies Most recent common ancestor of all living angiosperms Star anise and relatives Monocots Magnoliids Eudicots Figure 30.12 Angiosperm evolutionary history Ovules 300 250 200 150 100 50 0 Millions of years ago (a) A possible ancestor of the angiosperms? (b) Angiosperm phylogeny

Angiosperms: Monocots and Eudicots Monocot Characteristics Eudicot Characteristics Embryos One cotyledon Two cotyledons Leaf venation Veins usually parallel Veins usually netlike Stems Vascular tissue usually arranged in ring Vascular tissue scattered Roots Root system usually fibrous (no main root) Taproot (main root) usually present Figure 30.13 Angiosperm diversity Pollen Pollen grain with one opening Pollen grain with three openings Flowers Floral organs usually in multiples of three Floral organs usually in multiples of four or five

Mean difference in number of species Bilateral symmetry (N = 15) Can Flower Shape Influence Speciation Rate? EXPERIMENT Time since divergence from common ancestor “Bilateral” clade Compare numbers of species Common ancestor “Radial” clade RESULTS 3,000 2,000 Mean difference in number of species Figure 30.14 Can flower shape influence speciation rate? 1,000 Bilateral symmetry (N = 15) Radial symmetry (N = 4)

Table 30.1

Summary Five Derived Traits of Seed Plants Reduced gametophytes Microscopic male and female gametophytes (n) are nourished and protected by the sporophyte (2n) Male gametophyte Female gametophyte Heterospory Microspore (gives rise to a male gametophyte) Megaspore (gives rise to a female gametophyte) Ovules Integument (2n) Ovule (gymnosperm) Megaspore (2n) Megasporangium (2n) Pollen Pollen grains make water unnecessary for fertilization Seeds Seeds: survive better than unprotected spores, can be transported long distances Integument Food supply Embryo

Charophyte green algae Plant Evolutionary Relationships: Clades Charophyte green algae Mosses Ferns Gymnosperms Angiosperms

You should now be able to: Explain why pollen grains were an important adaptation for successful reproduction on land. List the four phyla of gymnosperms. Describe the life history of a pine; indicate which structures are part of the gametophyte generation and which are part of the sporophyte generation.

You should now be able to: Identify and describe the function of the following floral structures: sepals, petals, stamens, carpels, filament, anther, stigma, style, ovary, and ovule. Explain how fruits may be adapted to disperse seeds. Diagram the generalized life cycle of an angiosperm; indicate which structures are part of the gametophyte generation and which are part of the sporophyte generation. Describe the current threat to plant diversity caused by human population growth.