1. Seed Formation in Gymnosperms & Angiosperms

2. Mosses and other nonvascular plants
Fig. 30-2a
Mosses and other nonvascular plants
Gametophyte
Dominant
Reduced, dependent on gametophyte for nutrition
Sporophyte
Sporophyte (2n)
Gametophyte (n)
Example
Figure 30.2 Gametophyte/sporophyte relationships in different plant groups

3. Ferns and other seedless vascular plants
Fig. 30-2b
Ferns and other seedless vascular plants
Reduced, independent (photosynthetic and free-living)
Gametophyte
Sporophyte
Dominant
Sporophyte (2n)
Example
Figure 30.2 Gametophyte/sporophyte relationships in different plant groups
Gametophyte (n)

4. Seed plants (gymnosperms and angiosperms)
Fig. 30-2c
Seed plants (gymnosperms and angiosperms)
Reduced (usually microscopic), dependent on surrounding sporophyte tissue for nutrition
Gametophyte
Sporophyte
Dominant
Gymnosperm
Angiosperm
Microscopic female gametophytes (n) inside ovulate cone
Microscopic female gametophytes (n) inside these parts of flowers
Microscopic male gametophytes (n) inside these parts of flowers
Example
Figure 30.2 Gametophyte/sporophyte relationships in different plant groups
Microscopic male gametophytes (n) inside pollen cone
Sporophyte (2n)
Sporophyte (2n)

5. Fig. 30-2
PLANT GROUP
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
Reduced, dependent on gametophyte for nutrition
Sporophyte
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)

6. Pollen and Production of Sperm
Microspores develop into pollen grains, which contain the male gametophytes
Pollination is the transfer of pollen to the part of a seed plant containing the ovules
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

7. The Evolutionary Advantage of Seeds
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

8. Key Haploid (n) Diploid (2n) Pollen cone Mature sporophyte (2n)
Fig
Key
Haploid (n)
Diploid (2n)
Pollen cone
Microsporocytes (2n)
Mature sporophyte (2n)
Pollen grains (n)
MEIOSIS
Microsporangia
Microsporangium (2n)
Figure 30.6 The life cycle of a pine

9. Surviving megaspore (n)
Fig
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)
Figure 30.6 The life cycle of a pine

10. Key Haploid (n) Ovule Diploid (2n) Ovulate cone Megasporocyte (2n)
Fig
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)
Archegonium
Figure 30.6 The life cycle of a pine
Female gametophyte
Sperm nucleus (n)
Pollen tube
FERTILIZATION
Egg nucleus (n)

11. Surviving megaspore (n) Seedling
Fig
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)

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

13. Angiosperms
Angiosperms are seed plants with reproductive structures called flowers and fruits
They are the most widespread and diverse of all plants

14. Flowers
The flower is an angiosperm structure specialized for sexual reproduction
Many species are pollinated by insects or animals, while some species are wind-pollinated

15. A flower is a specialized shoot with up to four types of modified leaves:
Sepals, which enclose the flower
Petals, which are brightly colored and attract pollinators
Stamens, which produce pollen on their terminal anthers
Carpels, which produce ovules

16. (Male) Stigma Carpel (or Pistil) Stamen Anther Style Filament Ovary
Fig. 30-7
(Female)
(Male)
Stigma
Carpel
(or Pistil)
Stamen
Anther
Style
Filament
Ovary
Figure 30.7 The structure of an idealized flower
Petal
Sepal
Ovule

17. Video: Flower Blooming (time lapse)
A carpel (or pistil) consists of an ovary at the base and a style leading up to a stigma, where pollen is received
Video: Flower Blooming (time lapse)

18. Animation: Fruit Development
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

19. Tomato Ruby grapefruit Nectarine Hazelnut Milkweed
Fig. 30-8
Tomato
Ruby grapefruit
Nectarine
Figure 30.8 Some variations in fruit structure
Hazelnut
Milkweed

20. Various fruit adaptations help disperse seeds
Seeds can be carried by wind, water, or animals to new locations

21. Wings Seeds within berries Barbs
Fig. 30-9
Wings
Seeds within berries
Figure 30.9 Fruit adaptations that enhance seed dispersal
Barbs

22. 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

23. The Angiosperm Life Cycle (cont)
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

24. The Angiosperm Life Cycle (cont)
One sperm fertilizes the egg (now a zygote (2n)), while the other combines with two nuclei in the central cell of the female gametophyte and initiates development of food-storing endosperm (3n)
The endosperm nourishes the developing embryo
Within a seed, the embryo consists of a root and two seed leaves called cotyledons

25. Mature flower on sporophyte plant (2n) Microsporocytes (2n)
Fig
Key
Haploid (n)
Diploid (2n)
Microsporangium
Anther
Mature flower on sporophyte plant (2n)
Microsporocytes (2n)
MEIOSIS
Generative cell
Microspore (n)
Tube cell
Male gametophyte (in pollen grain) (n)
Pollen grains
Figure The life cycle of an angiosperm

26.
Each microspore divides by mitosis to form two haploid nuclei (the tube nucleus and the generative nucleus);
A diploid microsporocyte, or microspore mother cell, divides to give rise to four haploid microspores.
After landing on the stigma, the pollen germinates forming a pollen tube; the generative nucleus then divides by mitosis to form two haploid sperm nuclei.

27. Mature flower on sporophyte plant (2n) Microsporocytes (2n)
Fig
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
Megasporangium (2n)
Megaspore (n)
Antipodal cells Central cell (or polar bodies that form endosperm) Synergids Egg (n)
Figure The life cycle of an angiosperm
Female gametophyte (embryo sac)

28.
The remaining megaspore nucleus undergoes three mitotic divisions to form eight haploid nuclei.
A diploid megasporocyte (megaspore mother cell) undergoes meiosis, giving rise to four haploid megaspore nuclei (3 of which disintegrate).
Nuclear migration and cytokinesis occur to form the mature megagametophyte

29. Mature flower on sporophyte plant (2n) Microsporocytes (2n)
Fig
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
Stigma
Megasporangium (2n)
Pollen tube
Sperm
Megaspore (n)
Style
Antipodal cells Central cell Synergids Egg (n)
Figure The life cycle of an angiosperm
Female gametophyte (embryo sac)
Pollen tube
Sperm (n)
FERTILIZATION
Egg nucleus (n)
Discharged sperm nuclei (n)

30. Mature flower on sporophyte plant (2n) Microsporocytes (2n)
Fig
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 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)

31. Practice!!!