Kingdom Plantae Plant Diversity II

Transcription

1 Kingdom Plantae Plant Diversity II Professor Andrea Garrison Biology 3A Illustrations 2014 Cengage Learning unless otherwise noted Text 2014 Andrea Garrison

2 Plant Diversity II 2

3 Plant Classification Bryophytes nonvascular plants Phylum Hepatophyta liverworts Phylum Anthocerophyta hornworts Phylum Bryophyta mosses Seedless vascular plants Phylum Lycophyta club mosses Phylum Pterophyta ferns Phylum Psilotophyta whisk ferns (text incl in Pterophyta) Phylum Sphenophyta horsetails (text incl in Pterophyta) Now we move into seed plants Plant Diversity II 3

4 Plant Diversity II 4

5 Gymnosperms Seed not enclosed inside fruit (gymn=naked; sperm=seed) Seeds inside cone or similar structure Conifers, Ginkgos, Cycads (sego palms) Sizeable trees, shrubs Plant Diversity II 5

6 Gymnosperm Trends in Plant Evolution New adaptations allowed gymnosperms to be successful in a variety of new environments Increased size Major changes in methods of reproduction Plant Diversity II 6

7 Further Trends in Plant Evolution Increased size Apical meristem allowed increase in height Evolution of lateral meristem allowed secondary growth Increase in diameter as plant ages Plant Diversity II 7

8 Further Trends in Plant Evolution Reproductive adaptations Heterospory Sporophyte produces: Microspores male gametophyte Megaspores female gametophyte Retained inside sporangium and covered with integument Over time Microspores male gametophyte pollen» Many fossilized pollen grains from this period (Devonian) Megaspores developed integument» Retained inside reproductive structure» Similar to modern ovule which develops into seed Plant Diversity II 8

9 Modern Gymnosperms Spores sheltered inside parent plants Different than seedless plants which disperse spores Sporophyte produce haploid spores Retained inside reproductive structures Grow into multicellular gametophytes Male gametophyte = pollen grain» 2 non-motile sperm develop inside each pollen grain Female gametophyte with egg develops inside ovule Protected gametophytes more likely to survive Hidden inside parent sporophyte Plant Diversity II 9

10 Modern Gymnosperms Pollination = transfer of pollen to female reproductive parts of plant Accomplished by air, insects, birds Pollen grain grows into ovule and releases sperm Reproduction no longer requires water A few gymnosperms still have motile sperm that swim to egg Cycads & Ginkgoes Not very successful (few species) Plant Diversity II 10

11 Modern Gymnosperms Pollination leads to fertilization Fertilization produces sporophyte embryo Seed = embryo + food reserves for embryo + tough outer coat Much tougher than spores and small gametophytes, so seed species very successful Gymnosperm seed food reserves come from tissues of female gametophyte Embryo (in seed) grows in reproductive structure Same place where female gametophyte produced the egg Plant Diversity II 11

12 Phylum Coniferophyta Most common gymnosperms Pines trees Sequoias > 80 m tall Redwoods >112m tall Bristlecone pine One specimen >5000 yrs Most evergreens Shed some old leaves, but keep most of them Plant Diversity II 12

13 Phylum Coniferophyta Needle-like or scale-like leaves Adapted to dry habitats Thick cuticle Sunken stomata Fibrous epidermis Plant Diversity II; photos: top & bottom left by A. Garrison; bottom right by Walter Sigmund, 13

14 Phylum Coniferophyta Seeds inside cones (strobili) Plant Diversity II; photos by Didier Descouens, 14

15 Phylum Coniferophyta Seeds inside cones (strobili) Plant Diversity II; photo by A. Garrison 15

16 Phylum Coniferophyta Male and female cones dimorphic Male cones smaller, fragile Scales = sporophylls 2 microsporangia develop on underside of each scale Produce microspores Develop into pollen Plant Diversity II; photo by Menchi, 16

17 Phylum Coniferophyta Male and female cones dimorphic Females larger, longer lived Develop higher in tree Scales = sporophylls 2 ovules develop on each scale Megasporocyte in each ovule Meiosis 4 megaspores Only 1 megaspore survives Matures into female gametophyte slowly ( 1 yr in pine trees)» Completed during pollination» Several archegonia w/1 egg each Plant Diversity II; photo by A. Garrison 17

18 Phylum Coniferophyta Single tree may produce billions of pollen grains Female cone structure channels air currents to deposit pollen grains Once pollinated, scales close up Seed development can take up to 2 yrs Pollen grain grows tube into ovule Sperm released and fertilize egg Seed forms Scales open up and seeds released Some cones require fire for scales to open Plant Diversity II 18

19 Phylum Coniferophyta Seeds have wings that catch wind and help with dispersal of species Plant Diversity II; phots by Didier Descouens, 19

20 Coniferophyta Life Cycle Plant Diversity II 20

21 Phylum Cycadophyta Sego palms Strobilus in center Clusters of sporophylls Bear pollen or ovules Pollinated by air or beetles Some tissues toxic Seeds and flour edible if toxins rinsed away Plant Diversity II 21

22 Phylum Ginkgophyta Fan-shaped leaves Only found in wild in China Grown in nurseries Male is popular for landscaping Female has fleshy seeds with foul odor Plant Diversity II; photo by A. Garrison 22

23 Angiosperms Flowering plants Seeds enclosed in carpel (angi = enclosed; sperm = seed) Carpel later produces fruit Most diverse plants on earth Duckweed (1mm); Eucalyptus (100m) All angiospserms assigned to phylum Anthophyta (antho = flower; phyt = plant) Plant Diversity II; photo by A. Garrison 23

24 Phylum Anthophyta Very abrupt appearance in fossil record Evolutionary history not well understood Several clades Basal angiosperms Not monophyletic Magnolias, avocados Most monocots or eudicots Based on plant structure Plant Diversity II; photo by A. Garrison 24

25 Further Evolutionary Trends Modification of vascular tissue Allow more rapid transport of water up from roots and P/S products down from leaves Flower = reproductive structure Contribute to reproductive success of plants that bear them Enhanced nutrition and protection for embryos Double fertilization forms diploid zygote and nutritive tissue (endosperm) Ovule enclosed in ovary Protects against desiccation and predation Develops into fruit Protects and disperses seeds Plant Diversity II 25

26 Further Evolutionary Trends Most angiosperms require pollinators Internal flower structure complex Plants coevolved with specific types of pollinators Hereditary change in one species puts selective pressure on species that use it as a resource Nectar food source for many animal species As flowers changed, animal species changed with it Plant Diversity II 26

27 Further Evolutionary Trends Most angiosperms require pollinators Most flowers structured so pollen rubs off onto animals that feed from it Birds, bats, insects, rodents, etc. Flowers with deep calyx pollinated by hummingbirds or moths with long mouthparts Sweet scent attracts ants, bees Foul scent attracts flies, beetles Some flowers have target in center of plant only seen in UV light Bees see with UV light Plant Diversity II 27

28 Anthophyte Life Cycle Plant Diversity II 28

29 THE END

30 Modern Gymnosperms Coniferophyta Needle-like or scale-like leaves Adapted to dry habitats Thick cuticle Sunken stomata Fibrous epidermis Plant Diversity II 30