Gymnosperm & Angiosperm

Transcription

1 Gymnosperm & Angiosperm Rise of the seed plants 27

2 Gymnosperm: conifers Characteristics vascular heterospory male vs. female gametophytes seeds naked seeds (no fruit) pollen contain male gametophyte life cycle dominated by sporophyte stage coniferous trees you are familiar with are diploid reduced (microscopic) gametophyte reduction of gametophyte protects delicate egg & embryo in protective sporophyte protected from drought & UV radiation 28

3 Evolutionary trends in land plants Reduction in gametophyte bryophytes pteridophytes gymnosperm angiosperm 29

4 Early Gymnosperm: ginkgo 30

5 Early Gymnosperm: cycads 31

6 Gymnosperm: conifers 32

7 Cones & naked seeds 33

8 Gymnosperm (Pine) life cycle female gametophyte in cone meiosis meiosis male gametophyte in pollen sporophyte in seed fertilization 34

9 sporangium & pollen male (pollen) cones male female female cones pine embryo 35

10 Angiosperm: flowering plants Characteristics vascular heterospory male vs. female gametophytes flower specialized structure for sexual reproduction seeds within fruit pollen life cycle dominated by sporophyte stage trees & bushes you are familiar with are diploid reduced (microscopic) gametophyte 36

11 Angiosperm: flowering plants 37

12 Co-evolution: flowers & pollinators 38

13 Angiosperm: fruiting plants 39

14 Angiosperm life cycle 40

15 Flower Modified shoot with 4 rings of modified leaves sepals petals stamens male carpals female 41

16 42

17 Angiosperm life cycle male gametophyte in pollen fertilization female gametophyte in ovary sporophyte in seed 43

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19 Angiosperm Flowering plants flowers and fruit monocots 1 seed leaf leaves with parallel dicots 2 seed leaves leaves with net-like venation 45

20 Dicot dicots 2 seed leaves leaves with net-like venation broad leaf plants 46

21 Monocot monocots 1 seed leaf leaves with parallel grasses, grains, bulbs 47

22 Evolutionary trends Vascular tissue tubes for transport non-vascular bryophytes - mosses vascular pteridophytes - ferns gymnosperm - conifers angiosperm - flowering plants Evolutionary advantage? adaptation to dry terrestrial conditions allows increased size (think trees!) 48

23 Evolutionary trends Sperm dissemination flagellate (swimming) sperm bryophytes - mosses pteridophytes - ferns wind-blown or animal-carried pollen gymnosperm - conifers angiosperm - flowering plants Evolutionary advantage? adaptation to dry terrestrial conditions eliminated water requirement for fertilization 49

24 Evolutionary trends Seeds seedless plants bryophytes - mosses pteridophytes - ferns seed plants gymnosperm - conifers angiosperm - flowering plants Evolutionary advantage? adaptation for reproduction in diverse terrestrial environments resistant, dispersal stage 50

25 Evolutionary trends Reduction of gametophyte gametophyte dominant bryophytes - mosses sporophyte dominant, free living gametophyte pteridophytes - ferns sporophyte dominant, reduced gametophyte gymnosperm - conifers angiosperm - flowering plants Evolutionary advantage? adaptation for reproduction in diverse terrestrial environments reduction of gametophyte protects delicate egg & embryo in protective sporophyte protected from drought & UV radiation 51

26 Evolutionary trends The 4 groups represent 4 great episodes in the evolution of land plants evolution of land plants from ancestral green algae mosses evolution of vascular plants ferns evolution of seeds gymnosperm evolution of flowers angiosperm 52