Gymnosperms • Gymnosperms are plants that produce naked seeds – or seeds that are not covered by a protective fruit.
Gymnosperms • Every gymnosperm produces naked seeds (they are not surrounded by a protective fruit) • Many gymnosperms have needle-like or scalelike leaves, and deep-growing root systems.
Gymnosperms • Gymnosperms are the oldest seed plants • They first appeared on Earth about 360 million years ago • There were many more types of gymnosperms in the past. Today, only four groups of gymnosperms exist.
Types of Gymnosperms - Cycads • About 175 million years ago, the majority of plants were cycads. • Today, cycads grow mainly in tropical and subtropical areas • They look like palm trees with cones.
Types of Gymnosperms - Conifers • Conifers, or cone bearing plants, are the largest and most diverse group today. • Most conifers keep their leaves year round (pines, junipers, and evergreens)
Types of Gymnosperms - Ginkgoes • Ginkgoes also grew hundreds of millions of years ago, but today only one species still exists.
Types of Gymnosperms - Gnetophytes • Gnetophytes live in hot deserts and in tropical rain forests. • Some are trees, some are shrubs, others are vines.
Reproduction in Gymnosperms • Most gymnosperms have reproductive structures called cones • There are both female and male cones – usually one plant produces both types of cones. • In some plants, individual plants produce each type.
Reproduction in Gymnosperms • 1) Pollen falls from a male cone onto a female cone • 2) Asperm cell and an egg cell join together (fertilization) in an ovule on the female cone • 3) The seed develops on the scale of the female cone.
Reproduction in Gymnosperms Male Pine Cone Female Pine Cone
Gymnosperms in Everyday Life • Paper and other products, such as lumber used to build homes, come from conifers. • Because conifers are so useful to humans, they are grown in large, managed forests in many regions of the US.