Gymnosperms By Ala Maher and DanahAlaa
Gymnosperms-What are they? • Gymnosperms are land plants that produce seeds • An example of a gymnosperm is a red spruce tree (the trees with the needle-like leaves )
How many types? • There are THREE types of gymnosperms • #1: Gnetae • #2:Ginkgos • #3:Cycads
Gnetae • A subdivision/class that is supposedly the link between conifers and angiosperms
Ginkgos • Ginkgos are an extremely rare genus of non flowering plants (plants with no flowers) • They used to be much more common but today only one species is left (Maidenhair Tree)
Cycads • Cycads are a type of seed plant • Like ginkgos, cycads were common millions of years ago and today very few species exist • Cycads are found in tropical and subtropical regions
Why is the most important thing about gymnosperms? • They reproduce through cones
Cones • There are two types of cones: • #1: Pollen cones (the male cone) • #2: Seed cones (the female cone) • The pollen cones (male) produce pollen grains and the seed cones (female) produce ovules.
Life cycle of a gymnosperm • #1: Grains from the pollen cone (male) are carried by the wind. These grains fertilize the seed cone (female) • #2: Mitosis happens and sperm is produced • #3: The sperm cells leave the grains and fertilize the ovules. • #4: The cones scales (called zygotes) grow into seeds • #5: When the cone matures, it will grow into a tree but only if it is in fertile soil. This tree will then go on to produce more trees.
Refrences • Bowers, R. (2002). The Plants. Addison Wesley biology 11 (pp. 439, 440). Toronto: Addison Wesley. • Farlex. (n.d.). Gnetae - definition of Gnetae by the Free Online Dictionary, Thesaurus and Encyclopedia.. Dictionary, Encyclopedia and Thesaurus - The Free Dictionary. Retrieved October 3, 2012, from http://www.thefreedictionary.com/Gnetae