Gymnosperm notes

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Gymnosperm notes

  1. 1. KINGDOM PLANTAE <ul><li>NON-VASCULAR </li></ul><ul><ul><li>Phylum Bryophyta </li></ul></ul><ul><ul><li>Phylum Cholorphyta, Rhodophyta, Phaeophyta </li></ul></ul><ul><li>VASCULAR </li></ul><ul><ul><li>Phylum Tracheophyta </li></ul></ul><ul><ul><ul><li>Seedless – Class Filicinae </li></ul></ul></ul><ul><ul><ul><li>Naked Seeds – Class Gymnospermae </li></ul></ul></ul><ul><ul><ul><li>Seeds in Fruit – Class Angiospermae (mono / dicots) </li></ul></ul></ul>
  2. 2. PLANTS INVADE LAND <ul><li>The bryophytes and ferns did a relatively good job of invading the wetter parts of the land environment, but one critical weakness kept them from spreading farther:  the need for water to get sperm from male to female plants (or plant parts).  </li></ul><ul><li>Both had developed wind-blown spores to spread asexually, but as we've seen, asexual reproduction limits the speed that organisms can adapt to new environment, and the land was full of new environments.  </li></ul>
  3. 3. What is Pollen? <ul><li>The adaptation that really led to an evolutionary leap was pollen , a tiny male gametophyte that, in its first versions, could be carried by the wind to the female gametophytes and sprout a &quot;tunnel&quot; into them that a sperm could travel down.  </li></ul><ul><li>No longer would the two genders have to be close to one another and need some sort of open water between them for the sperm to swim through.  </li></ul><ul><li>Plants would still need water for their chemistry and specifically for photosynthesis, but they wouldn't be limited to environments where open water was periodically available.  </li></ul><ul><li>These new types of plants could carry gametophytes high above the ground, where sporophyte embryos could be encased with some &quot;starting off&quot; food and also be set off in the wind.  </li></ul><ul><li>The casings with little sporophytes in them were seeds, and all of the groups to evolve from pollen-bearing plants would also be seed plants.    </li></ul>
  4. 5. <ul><li>Seed plants are all vascular plants , with an internal tube system that brings water and nutrients up from the roots through thick-walled xylem tubes, and phloem, that carry fuel back to the roots for use and for storage.  </li></ul><ul><li>There are two major types of seed plants:  the gymnosperms   (Latin for &quot;naked seeds&quot;) and the angiosperms (Latin for &quot;covered seeds,&quot; sort of).  </li></ul>
  5. 6. Divisions of Gymnosperms <ul><li>There are 4 groups within the Gymnosperms:  </li></ul><ul><li>Cycads : resemble short palm trees </li></ul><ul><li>Gingkos, mostly known because some Chinese species have been used in landscaping around the world </li></ul><ul><li>Gnetales : share some traits with angiosperms </li></ul><ul><li>Conifers : cone-bearing shrubs and trees.  </li></ul><ul><li>The conifers are the best-known gymnosperms, and our discussion of gymnosperm life-cycles will center on conifers.  </li></ul><ul><li>The gymnosperms were probably the first really widely-distributed plant group, and with their rise came the rise of a major animal group:  the dinosaurs. </li></ul>
  6. 7. Cycad
  7. 8. Gingkos <ul><li>Ginkgoes are often planted in cities not only because they're pretty trees but also because they thrive where air pollution is bad. </li></ul><ul><li>It's not surprising that ginkgoes are air-pollution tolerant, because they are very primitive plants; they may have evolved when the earth's atmosphere was even more sulphurous and grimy than today, because of erupting volcanoes. </li></ul><ul><li>Ginkgoes are living fossils </li></ul><ul><li>Deciduous </li></ul><ul><li>Seed coat turns fleshy not ovary wall </li></ul>
  8. 9. Gnetales <ul><li>Gnetum gnemon </li></ul><ul><li>Ephedra </li></ul>
  9. 10. Conifers <ul><li>Conifer forest </li></ul>
  10. 11. Gymnosperm Life cycle <ul><li>When you see a pine tree, a spruce or a cone-bearing shrub, the &quot;main plant&quot; is a sporophyte </li></ul><ul><li>The gametophyte form is confined to the cones which commonly have male and female versions.   </li></ul><ul><li>In many trees (though not all) </li></ul><ul><ul><li>the males cones are smaller and located at the tree tops </li></ul></ul><ul><ul><li>the female cones are larger and found farther down.   </li></ul></ul><ul><li>The sizes relate to the needs of the two genders:  </li></ul><ul><ul><li>the female cones will generate seeds, and will need to be bigger </li></ul></ul><ul><ul><li>the male cones just produce tiny wind-carried pollen (and even though a lot of pollen is made, not much room is needed for it).  </li></ul></ul>
  11. 12. <ul><li>The location on the trees reflects how the pollen is wind-spread, with the male cones as high as can be for best wind access, and the female cones lower since much of the pollen will settle eventually. </li></ul>
  12. 14. Pollination <ul><li>The transfer of the entire microgametophyte (pollen grain) to the vicinity of the megagametophyte (cone) </li></ul><ul><li>Wind or animals usually do this </li></ul>
  13. 17. Roles and Uses of Gymnosperms <ul><li>Roots of conifers supply amino acids to some fungi (eg.mycorrhiza) </li></ul><ul><li>Food </li></ul><ul><ul><li>Stems of cycads/seeds ofginkgo sources of starch </li></ul></ul><ul><ul><li>Needles of eastern white pine are rich in Vitamin C </li></ul></ul><ul><li>Paper </li></ul><ul><ul><li>white spruce ins the main source of pulpwood </li></ul></ul><ul><li>Fuel </li></ul><ul><li>Lumber </li></ul>

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