Bacteria to Plants
Notes 5.2 Gymnosperms
What Are Gymnosperms?
Gymnosperms are seed plants that do not produce seeds protected by a fruit,
otherwise known as “naked” seeds. They also may have needle-like or scale-like
leaves.
Gymnosperms are the oldest seed plants, dating back to 360 million years ago.
Four types of Gymnosperms…
1) Cycads-Look like palm trees that have a cone.
Example: sago palm.
2) Conifers-Plants that produce cones.
-Most are evergreens, meaning that they keep their leaves year round.
Examples: pine tree, junipers
3) Ginkgoes-Only one species remains alive today.
4) Gnetophytes-Live in deserts and tropical rain forests.
Reproduction in Gymnosperms
Most gymnosperms have reproductive structures known as cones, which are
covered with scales. Most gymnosperms have both male and female cones.
Male cones produce tiny grains of pollen, the male gametophyte. Pollen contains
the cells that eventually become sperm cells.
Female cones produce egg cells, the female gametophyte. Egg cells develop in
structures called ovules, which are found at the base of each scale of the cone.
During reproduction, pollination occurs when pollen falls from the male cone onto
a female cone. In time, a sperm cell and an egg join together in an ovule on the
female cone. The ovule then closes and develops into a seed. The cone opens
when the seed is mature and the wind helps to shake out the seeds and move them
away.