4/15/2013 Gymnosperms Angiosperms Pterophytes Seeds Plant Reproduction Lycophytes Bryophytes Vascular tissue Green algae: BI 103 Plant-Animal A&P Chlorophytes Turn in Homework #1 Land plants Angiosperm specific adaptations • Unlike other plants they have: Why do plants have flowers? In – Flowers other words, what are the – Double fertilization advantages of flowering? – Fruit Discuss this question in groups Alternating Generations In more advanced plants, the sporophyte generation is Angiosperms: the Flowering plants dominant. Why do plants have flowers? Enlists partnerships with insects and other animals Less inbreeding Higher probability the pollen will reach the right plant They don’t have to produce as much pollen 1 4/15/2013 How is pollen an adaptation to land? Alternation of generations modified Allows fertilization to occur even in the absence • Pollen= Male gametophyte of available water. Contains sperm • Ovule= Female gametophyte water Contains egg Moss fertilization Pollen grains Anthers with microspores Microspore to pollen 1. The microspores divides by mitosis to produce two cells Generative cell (1n) Tube cell== vegetative nucleus (1n) 2. A two layered wall develops around the microspore to become the pollen 3. The generative cell undergoes division once more 3n total (3 nuclei) in pollen Double fertilization Fruit development 1. Two pollen nuclei enter ovule 2. One fuses with the egg to form the zygote 3. The other fuses with 2 central cell nuclei to become the endosperm (3n), food for the zygote Becomes the seed! Becomes the fruit! 2 4/15/2013 Why do we see such diversity in the Pollination syndrome flowers we see? Theory: Coevolution of plants and pollinators Different flowers have evolved to attract different Floral characteristics which attract a specific pollinators- plants have specialized to a specific group of pollinator group of pollinators Bees, hummingbirds, moths etc Allows flowers to specialize May include mechanisms to exclude other pollinators Pollination syndrome Bees Blue What are the advantages to specializing to one species or one group of pollinator? Symmetrical Smells sweet What are the disadvantage or risks? Pollen Most flowers are ‘generalists’ and do not rewards specialize. Nectar rewards Pheromone rewards Bees Pollinators: Bees UV Markings Blue Symmetrical Bees can see in UV! UV marking Smells sweet Nectar guides ---Example: Catalpa speciaosa 3 4/15/2013 Bee specialization Pedicularis attollens, common name:“Baby Elephant’s head” Bumble bee pollinated Pedicularis attollens Specialized Buzz pollination Birds: hummingbirds Red Long and tubular Technique only used by bees to release pollen No odor from anthers– they must hit the right musical note! nectar Example: Tomatoes, blueberries, manzanita (Arctrostaphylos) https://www.youtube.com/watch?v=Nv_xncrZ fCg&feature=related Moths Moths Darwin’s Orchid, Angraecum sesquipedale White flowers Hawkmoth on Columbine (Aquileia) Sweet smell Open at night Long nectar spur with nectar 4 4/15/2013 Why are those spurs so long? Predator: Crab spider Combination of: Moths don’t want to get too close…. Predators lurk! Plant needs moth to get close enough to reach pollen and stigma Bats Butterflies Strong pedicle and petals Musky odor Sweet smell White Vibrant colors Open at night & lots of pollen Larger flowers Ex: Sargo cactus Nectar rewards Flies: rancid smell, tiny, green or Announcements reddish • Homework #2 Design a flower --Due next Monday 4/22 • Lab report– due Wed in lab • Outdoor lab section? 5 .