1. Evolution of the seed

2. Adaptations of seed plants
Seeds
Reduced gametophyte stage
Also seen in seedless vascular
seed plants reduced to microscopic (spores develop in sporangia of sporophyte)
Heterospory
Megaspores – make female gametophyte
Microsporangia – male gametophyte
Ovules = megaspore & integuments (protect)
Pollen = micro (male gametophyte) & sporopollenin

3. Microsporangium: on anther

4. Megasporangium Ovary produces the ovule Ovule parts: INTEGUMENT
MACROSPORAGIA
FEMALE GAMETOPHYTE (egg)

5. Seed Seed : Ovule develops into seed Cotyledons: 1 or 2 seed leaves
Embryo: immature plant
Endosperm:food supply
Seed coat of integument
Ovule develops into seed
Cotyledons: 1 or 2 seed leaves

6. Seed parts
Embryo
Endosperm
Seed coat

7. Seed Double Fertilization Endosperm
The union of two sperm cells with different nuclei of the embryo sac.
Endosperm
Food storing tissue of the seed.

8. Seed to Seedling
Imbibition is that state when the seed wakes up from dormancy and starts the intake of water.
It causes the seed to expand and ruptures, releasing the shoot, the cotyledons and the stalk.
It is the first sign of life after the dormant state.

9. Seed to Seedling http://students. usm. maine. edu/deidre

10. Spore survival
Prior to seeds: spore was the only protected stage for plants.
Spore is single cell
Could survive: cold hot dry
Could be dispersed to another environment

11. Spore Release

12. Then, seeds Seeds are multicellular
Has protective integument coat from ovule
Can be dormant for days months years

13. Seed Release

14. Vascular Seed plants Gymnosperms: fir, pine
Angiosperm: flowering plants

15. Pine tree The pine tree is the sporophyte (2N)
Its sporangia are located on the pine cone
Heterosporous
Small pollen cones: carried by wind and critters
Large ovule cones
Each tree has both types of cones

16. Female - Male
female
male

17. Angiosperm Flowering plants: vascular and seeds
Most diverse and widespread plants
Flower: specialized for reproduction
Carried by wind: like gymnosperm
Carried by insects: more directed pollination
Fruit: protect seed and aid in dispersal
From ovary. Ovary thickens after pollination.

18. Flower Structure
Four main organs: sepals, petals, stamens, and carpels
Stamens and carpels are reproductive
Carpel:
Stigma: collects pollen
Style: to ovary with 1 or more ovules
ovary
Pistil: multiple fused carpels
Stamen: filament, anther
Anther: stalk where pollen made
Sepals and petals: no repro organs

19. Gametophyte Development and Pollination
Sporangia- structure on
anther and
ovules where spores are produced
Pollen grains are made up of mature male gametophytes that are enclosed by a spore wall
Found in the microsporangia, or pollen sacs

20. Hormones Auxin Stem elongation, root growth, develop fruit
Cytokinins: affect, cell division, cell differentiation, and apical dominance.
Gibberellins
Seed and bud germination
Abscisic acid
Inhibit root growth, close stomata
Ethylene
Fruit ripening

21. Mechanisms that Prevent Self-Fertilization
Sexual reproduction ensures that there will be genetic diversity among offspring
“Selfing” refers to self-fertilization in plants
Ensures that seed will develop

22. Pollination Vs. Fertilization
Pollination is the transfer of pollen from anther to stigma (of other plant)
Results in formation of a pollen tube
Purpose is to grow down to ovary and release sperm within embryo sac
This fertilizes the egg
Embryo -> seed -> fruit containing seed
The fruit disperses seeds which germinate and develop into seedlings

23. Development Microsporocytes form four haploid microspores
These develop into haploid male gametophytes
The microspore goes through mitosis and cytokinesis
This results in a generative cell and tube cell which make up the pollen grain

24. Megasporocyte grows resulting in four haploid megaspores
May form a multicellular female gametophyte
Contains 3 cells: 1 egg and 2 synegrids
Synegrids attract and guide pollen tubes to the embryo sac
there are also two nuclei at the other end of the cell that are not separate and share cytoplasm embryo sacs
These result in two integuments that form a seed

25. Ensuring that the egg and sperm cells come from different parents is a mechanism that inhibits self fertilization
Dioecious plants cannot self fertilize because they have either staminate or carpellate flowers

26. Avoid self fertilization
Flowers with functional stamen and carpels have organs that mature at different rates
An animal pollinator would not transfer pollen from the anther to a stigma of the same flower

27. Self Incompatibility The ability of a plant to reject its own pollen
Also, in some cases, the pollen of similar plants
If pollen were to land on the stigma of a flower on the same plant a biochemical would prevent the pollen from developing and fertilizing an egg

28. Special Circumstances
Plant breeders will hybridize different crop varieties to combine the best traits and to get sufficient results
This can result in inbreeding
May cause plants that are able to self fertilize to lose that characteristic.