2. Flowering Plants - Angiosperms

3. Flowering Plants - Angiosperms
Largest group of Land Plants!
Most important economically!
Apomorphies:
Flowers
Carpels
Fruits
Double fertilization with triploid endosperm
Specialized conductive cells

4. Why have Angiosperms been so successful?

5. Flowers What is a flower?
= Shoot system bearing modified leaves:
Perianth
Calyx (sepals) - green, protective
Corolla (petals) - colored, attractant
Stamens - male
Carpels - female }
modified
leaves

6. pistil
Fig. 30.7

7. Flower parts:

8. Flower pollination (transfer of pollen to ovule):
Animal pollination
Ancestral for Angiosperms
Much more efficient means of transporting pollen
All Gymnosperms are wind pollinated
(Some Angiosperms secondarily wind pollinated)

9. Strategy of animal pollination:
Attractant
Visual: large or brightly colored perianth
Olfactory (smell): sweet or rotten (fetid) odor
Reward
Usually nectar or pollen
(Rarely waxes, oils)

10. Pollination Mechanisms
Insects
Bees
Butterflies/Moths
Flies
Birds
Bats
Water
Wind

11. Bee-pollinated

12. Moth-pollinated

13. Fly-pollinated

14. Bird-pollinated

15. Bat-pollinated

16. Wind pollination in grasses

17. Water-pollinated
Phyllospadix torreyi
Surf-Grass

18. 2) Carpels Carpel = conduplicate megasporophyll
Conduplicate = folded
Megasporophyll = “female leaf, bearing seeds”
Carpel totally encloses ovules/seeds

19. Carpels can fuse together
Gynoecium = all female parts
Pistil = ovary + style + stigma Pistil can be one carpel or many

20. orange: 8 fused carpels
carpel

21. Function of Carpel Protects young seeds
Site of pollen germination - Can induce self-incompatibility reactions
Fruits

22. Self-incompatibility - Pollen will not germinate on genetically similar individuals - Promotes outcrossing

23. 3) Fruits Fruit = mature ovary (plus accessory parts)
Function: seed dispersal

24. Fruit types: dry - dispersed mechanically, by wind, water, etc
Fruit types: dry - dispersed mechanically, by wind, water, etc. fleshy - dispersed by animals

25. 4) Double fertilization in Angiosperms
Assignment:
Study Figs. 38.2, 38.3, 38.5

26. Double fertilization in Angiosperms
Pollen produces 2 sperm cells:

27. Double fertilization in Angiosperms
Pollen produces 2 sperm cells:
sperm (n) + egg (n) ----> zygote (2n)
sperm (n) polar nuclei (n) ----> endosperm (3n)

28. Triploid endosperm is nutritive tissue in seeds of Angiosperms.
Extra set of genes may help in: 1) rapid development 2) increase genetic variation

29. Gymnosperms: - Fertilization occurs long after pollination
- Seeds mature slowly (1-2 years)
Angiosperms: - Fertilization occurs soon after pollination
- Seeds produced rapidly
- Selective advantage (e.g., annual herbs)

30. 5) Specialized conductive cells Most Angiosperms have vessels
Specialized in having perforation plates
vessel
perforation plate

31. All Angiosperms have sieve tube members
-with sieve plates: bigger pores in end walls
big
callose-lined
pores

32. Angiosperms Vessels and sieve tube members
more efficient in water / sugar conduction

33. Angiosperm Classification

34. { Old classification: Dicots - 2 cotyledons (seed leaves) Monocots
embryo
seed coat
radicle
epicotyl
hypocotyl
2 cotyledons
endosperm
NON-MONOCOT {
Old classification:
Dicots
- 2 cotyledons (seed leaves)
Monocots
- 1 cotyledon
radicle
epicotyl
hypocotyl
1 cotyledon
embryo
coleorhiza
coleoptile
MONOCOTS

35. Monocots
monophyletic

36. Monocot apomorphies

37. Monocot apomorphies 1 cotyledon parallel venation stem an atactostele
radicle
epicotyl
hypocotyl
1 cotyledon
embryo
coleorhiza
coleoptile
MONOCOTS
1 cotyledon
parallel venation
stem an atactostele
-many scattered vascular bundles (wood lost!)

38. Monocots include:
Palms
Orchids
Irises
Grasses, etc.

39. “Dicots”
paraphyletic!

40. Features that defined “Dicots” are primitive (not apomorphies)

41. Eudicots
monophyletic!

42. Pollen tricolpate - 3 apertures
Eudicot apomorphy: A A A
Pollen tricolpate apertures

43. All other Angiosperms:
aperture
Pollen has 1 aperture

44. Eudicots include most angiosperms:
Roses
Legumes
Daisies
Oaks, etc.