Plant Reproduction: Seed Plants 8SCIENCE: Mon. March 14th/Tues. March 15th
Seed Plants Seed plants reproduce sexually Fertilization from male and female sex cells Two types: Gymnosperms E.g. Pine trees with cones Angiosperms E.g. Most have flowers
Gymnosperms Means ‘naked seed’ = needs the cone to protect it! Cones are the reproductive structures on gymnosperms and each species has a different type of cone Male and female cones are produced on the same plant: Female cones have ovules, which contain the egg cells Male cones develop pollen grains, which contain sperm cells
Gymnosperms continued… Male cones release a cloud of pollen Wind usually carries the pollen to the female cone The pollen is trapped by a sticky substance and develops into a pollen tube Grows towards the ovule and sperm can fertilize the egg cell Can take 15 months!
Gymnosperms…there’s more! After fertilization, an embryo forms and develops into a seed When female pine cones mature, they open and release their seeds These can be carried away, or are eaten or buried by animals Buried seeds may grow into new pine trees!
Angiosperms All produce flowers Can be brightly colored or have a nice smell to attract animals Animals like birds (hummingbirds) or insects (bees) can help spread pollen to other flowers When pollen from the stamen lands on the stigma, this is called pollination The same process occurs in gymnosperms, where a pollen tube grows into the ovule and eventually a seed will develop)