1. Plant reproduction
Chapter 38

2. Fig. 38.3

3. Plant life cycle Alteration of generations Haploid (n) Diploid (2n)
Sporophyte:
Diploid plant produces haploid spores by meiosis
Gametophyte:
Haploid plant produces diploid zygotes by fertilization

4. Angiosperms Gametophyte generation very small
Enclosed within the parent sporophyte
Pollen grains:
Male gametophytes
Embryo sac:
Female gametophytes
Gametes produced in separate structures

5. Life cycle

6. Flower structure Sepals Protect the flower Petals Attract pollinators
Stamens: male structures
Filaments: “stalks”
Anther: swollen portion at the top

7. Flower structure Carpels: female structures
Ovules: develops into seeds
Ovary: contains ovules
Style: slender neck-like structure
Stigma: top collects pollen

8. Flower structure

9. Seed Development

10. Male gametophytes Pollen formation Pollen sacs in anther
Microspore: (mother cell)
Meiosis
4 haploid cells
4 pollen grains
Inside is a generative cell
Divides later to form 2 sperm

11. Female gametophytes Egg formation Ovules
Contain a megaspore mother cell
Undergoes meiosis 4 haploid cells
3 die (disintegrate) one lives
Undergoes mitosis 8 haploid nuclei
Arranged in specific order in embryo sac

12. Female gametophytes 1 at opening of embryo sac (egg cell)
2 (single cell) at center polar bodies
2 contained in cells called synergids on either side of the egg cell
3 called antipodals at opposite end from egg cell

14. Fertilization Pollen sticks to sugary substance on stigma
Grows pollen tube
Reaches ovule
Pollen grain divides into two sperm
One of the synergids degenerates
Tube penetrates the ovule

15. Fertilization Double fertilization 2 sperm are used
1. Sperm fertilizes egg-zygote (2n)
2. Sperm fuses with polar bodies
Forms endosperm (3n)

18. Fertilization

19. Seed formation Ovule develops into a seed Ovary develops into a fruit
Endosperm develops first
Stores food for seed
Most monocots & some eudicots
White coconut meat-endosperm
White part of popcorn-endosperm

20. Seed structure Seed coat: Protective covering Cotyledons: Seed leaf
Help with embryo development
Dormancy
Imbibition:
Uptake of water–starts germination

21. Fig. 38-8 Seed coat Epicotyl Hypocotyl Radicle Cotyledons
(a) Common garden bean, a eudicot with thick cotyledons
Seed coat
Endosperm
Cotyledons
Epicotyl
Hypocotyl
Radicle
(b) Castor bean, a eudicot with thin cotyledons
Scutellum
(cotyledon)
Pericarp fused
with seed coat
Endosperm
Coleoptile
Epicotyl
Hypocotyl
Coleorhiza
Radicle
(c) Maize, a monocot

22. Fig. 38-9
Foliage leaves
Cotyledon
Epicotyl
Hypocotyl
Cotyledon
Cotyledon
Hypocotyl
Hypocotyl
Radicle
Seed coat
(a) Common garden bean
Foliage leaves
Coleoptile
Coleoptile
Radicle
(b) Maize

23. Fruit Development

24. Fruit formation Ovary Simple fruits: Single carpel-pea, nectarines
Aggregate fruits:
Separate carpels
Raspberry
Multiple fruits:
Group of flowers-pineapples

25. Fig. 38-10 Stigma Carpels Style Stamen Flower Petal Ovary Stamen
Sepal
Stigma
Ovary
(in receptacle)
Ovule
Ovule
Pea flower
Raspberry flower
Pineapple inflorescence
Apple flower
Each segment
develops
from the
carpel
of one
flower
Remains of
stamens and styles
Carpel
(fruitlet)
Stigma
Sepals
Seed
Ovary
Stamen
Seed
Receptacle
Pea fruit
Raspberry fruit
Pineapple fruit
Apple fruit
(a) Simple fruit
(b) Aggregate fruit
(c) Multiple fruit
(d) Accessory fruit

26. Asexual reproduction Genetically identical individuals
Vegetative reproduction
Cuttings
Spider plants
Fragmentation
Roots give rise to new plants (Aspens)
Apomixis (seeds produced asexually)
Dandelions