Gymnosperms

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Pinus

MALE CONES
  • Cluster of male cones near the end of a stem. x12
  • A single young male cone ls x30. The cone is attached to a stem on the left.
  • Sporophylls of a mature male cone x20. The cone axis ls is on the right. Sporophylls are fertile leaves. They have sporangia with pollen on their lower surfaces.
  • Mature Pinus pollen x400. Each pollen grain has two nuclei and two hollow bladders. The bladders make the pollen grain very light and easy for the wind to blow around.
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    FEMALE CONES
  • First year female cone ls x20. Cone scales are separated to allow the entry of pollen.
  • Megaspore mother cell x100. This is a first year cone ls. The cone axis is on the right. An arrow indicates the megaspore mother cell in an ovule. This cell will divide by meiosis to make four megaspores, one of which will divide by mitosis to make the female gametophyte inside the ovule.
  • Second year female cone ls x12.
  • Second year ovule with pollen droplet x100. As the pollen droplet dries it draws pollen into the pollen chamber of the ovule. The cone axis is on the right.
  • Second year ovule with pollen in pollen chamber x40. In this illustration the cone axis is on the left
  • Micropyle and pollen chamber containing pollen x100.
  • Germinating Pinus pollen grain in pollen chamber x400. Note the branched pollen tube extending to the right. The pollen grain sits in the pollen chamber and the micropyle is off to the left.
  • Mature ovule just prior to fertilization x12. It sits on a cone scale that is attached to the cone axis off the right side of the illustration.
  • Archegonium median ls x40 in a mature ovule. The archegonium's neck, just above the egg, is only two cells in length.
  • Mature seed ls in 3rd year cone x12. The embryo sporophyte is in the center. The seed coat (integument) outside of the nutritive gametophyte is not shown in this specimen.
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    STEMS AND LEAVES
  • Wood cross section x30.
  • Wood tangential section x30.
  • Wood radial section x30.
  • Wood radial section showing circular bordered pits x100.
  • Circular boardered pits x400 in radial section.
  • Pair of leaves xs. x30.

    Other Gymnosperms

  • Zamia male cone ls x12.
  • Zamia ovule with archegonia x12.
  • Ginkgo male cone ls x12. The central cone axis bears short sporophylls that have sporangia on their lower surfaces. Pollen is in the sporangia.
  • Ginkgo mature ovule x12 (lower part of illustration), attached to its ovuliferous scale (upper part of illustration).
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