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Flowering Plants - Angiosperms

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Presentation on theme: "Flowering Plants - Angiosperms"— Presentation transcript:

1

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.

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