Gymnosperms Chapter 5 Section 2

What are Gymnosperms Seed Plant Naked seeds Not enclosed in a protective covering Needlelike or scale-like leaves Deep growing root system Examples Shrubs Most are trees

Types of Gymnosperms Cycads 175 million years ago most plants were Cycads Now mainly in tropical regions Look like palm trees with cones Large cones

Types of Gymnosperms Ginkgo Only one species Ginkgo biloba Survival due to Chinese and Japanese Can grow as tall as 25 meters Can tolerate pollution

Types of Gymnosperms Gnetophytes Least likely to see Live in hot dry deserts of South Africa and deserts of western United States Some are trees, shrubs or vines

Types of Gymnosperms Conifers Cone bearing plants Largest, most diverse group Pines, redwoods, cedar, hemlocks, junipers Evergreen plants Keep leaves (needles) all year

Reproduction Cones are the reproductive structure Most gymnosperms produce two kings of cones Male (pollen cone) Female (egg cone) Most plants produce both types of cones

Male cones Female cones Smaller than female Produce tiny grains of pollen Will later become sperm Male cones produce so many grains of pollen they can overflow the spaces between the cone’s scales. Female cones Contain at least one ovule Structure that contains the egg cell After fertilization the ovule will become the seed

Reproduction Life Cycle Pollen falls from make cone onto female cone Sperm and egg join in ovule of female cone Zygote develops into embryo part of seed

Pollination and Fertilization Transfer of pollen from the male reproductive structure to the female reproductive structure Wind transfers the pollen Pollen collects on sticky substance around ovule Scales of female cone close to seal in the pollen Fertilization occurs Seed develops on the scale Female cones stay on tree until seed are mature Could take years Male cones fall from tree when they lose their pollen

See Dispersal Female cone increases in size as seed grows Orientation on tree changes Immature seed- cone points upward Mature seed- cone points downward When seeds are mature Cone opens Wind shakes seeds from cones and carries them away Only a few seed will land in suitable surroundings

Gymnosperms and the Living World Products from conifers Paper, wood products Used for rayon in clothes Turpentine and rosin from sap Clear cutting All trees in a large area are cut down