Jira
GYMNOSPERMS
- phlya Ginkgophyta, Gnetophyta, Cycadophyta and Coniferophyta - vascular plants with true roots - gymnosperms = “naked seeds” - cones/strobili - have seeds that develop on the surfaces of sporophylls instead of in ovaries like angiosperms - microsporangium produces pollen grains (sperm) and the megasporangium produces the egg - sporophyte generation is dominant - no water needed for fertilization – pollen travels with the wind
Pine trees - monoecious (separate male and female cones on the same plant) - have needle-shaped leaves that adapt the tree to dry conditions - produce cones – male and female - male cones produce microsporangia (pollen sacs) that produce microspores (4) which mature into pollen grains (microgametophyte) with wings for wind dispersal - female megasporocytes within the ovule undergo meiosis early producing megaspores (4) of which three degenerate and one is functional – this one undergoes mitosis to produce the female gametophyte (megagametophyte) = egg which lies in the archegonium - Fertilization – pollen sticks to female scales to a drop of fluid which evaporates moving the pollen closer to the megasporangium and then the scales close. Pollen tube then grows down into female gametophyte and the pollen divides into 2 sperm – one fertilizes the egg to produce a zygote and the other disintegrates. - Seed coat then surrounds embryo and wings develop for dispersal
Pine Life Cycle: [pic] (Vodopich and Moore, pg 307)
Leaves arranged in bundles (fascicles) [pic] http://www.science.siu.edu/landplants/Coniferophyta/images/Pine.needles.JPEG Female (Ovulate) Cones
[pic]
http://www.science.siu.edu/landplants/Coniferophyta/images/Pinus.cones.JPEG
Immature female cones (winter)
[pic] http://www.science.siu.edu/landplants/Coniferophyta/images/Pinus.yng.cone.JPEG
- phlya Ginkgophyta, Gnetophyta, Cycadophyta and Coniferophyta - vascular plants with true roots - gymnosperms = “naked seeds” - cones/strobili - have seeds that develop on the surfaces of sporophylls instead of in ovaries like angiosperms - microsporangium produces pollen grains (sperm) and the megasporangium produces the egg - sporophyte generation is dominant - no water needed for fertilization – pollen travels with the wind
Pine trees - monoecious (separate male and female cones on the same plant) - have needle-shaped leaves that adapt the tree to dry conditions - produce cones – male and female - male cones produce microsporangia (pollen sacs) that produce microspores (4) which mature into pollen grains (microgametophyte) with wings for wind dispersal - female megasporocytes within the ovule undergo meiosis early producing megaspores (4) of which three degenerate and one is functional – this one undergoes mitosis to produce the female gametophyte (megagametophyte) = egg which lies in the archegonium - Fertilization – pollen sticks to female scales to a drop of fluid which evaporates moving the pollen closer to the megasporangium and then the scales close. Pollen tube then grows down into female gametophyte and the pollen divides into 2 sperm – one fertilizes the egg to produce a zygote and the other disintegrates. - Seed coat then surrounds embryo and wings develop for dispersal
Pine Life Cycle: [pic] (Vodopich and Moore, pg 307)
Leaves arranged in bundles (fascicles) [pic] http://www.science.siu.edu/landplants/Coniferophyta/images/Pine.needles.JPEG Female (Ovulate) Cones
[pic]
http://www.science.siu.edu/landplants/Coniferophyta/images/Pinus.cones.JPEG
Immature female cones (winter)
[pic] http://www.science.siu.edu/landplants/Coniferophyta/images/Pinus.yng.cone.JPEG