Gymnosperms A seed plant that produces “naked” seeds What are gymnosperms? • Seed plants that produce seeds NOT enclosed in a protective fruit. • Many have needle-like leaves • Deep growing root systems • Oldest type of seed plant-giant sequoias 4 groups of gymnosperms • • • • Cycads Conifers Ginkgoes Gnetophytes Cycads • Grow mainly in tropical areas • Look like palm trees with cones Conifers • • • • Cone-bearing plants Most are evergreens Pine trees, junipers, sequoias Largest, most diverse groups Ginkgoes • Only one species lives today • Grew millions of years ago • Can tolerate air pollution-so planted along city streets Gnetophytes • Live in hot deserts and tropical rain forest • Some are trees, others shrubs or vines reproduction • Most involves CONES-covered with scales • Most gymnosperms produce male and female cones • Male cones produce pollen which contain cells that will become sperm cells. • Female cones contain ovules which contain the egg cell Pollination • Transfer of pollen from the male reproductive structure to the female reproductive structure • Usually carried by wind • Collects on a sticky substance produced by the ovule Fertilization • After pollination, the ovule will close and seal in the pollen. • The sperm cell fertilizes the egg cell • The fertilized egg (zygote) develops into the embryo • It can take up 2 years for the seed to mature Germination • Once the seeds mature, the scales open • Wind shakes the seeds out and carries them away • If seeds land in favorable conditions, the seed will sprout--germinate Useful products • • • • • • • Paper Lumber Rayon fibers Cellophane wrap Turpentine Rosin These are renewable resources!