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Plant Diversity 22-4 & 22-5. Seed Plants. The seed was major step in the evolution of land plants. It allowed plants to be able to colonize dryer areas of land. Seed Plants. - PowerPoint PPT Presentation
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Plant Diversity 22-4 & 22-5
Seed PlantsThe seed was major step in the evolution of land plants. It allowed plants to be able to colonize dryer areas of land.
Seed PlantsAdaptations that allow seed plants to
reproduce without water include flowers or cones, the transfer of sperm by pollination, and the protection of embryos in seeds.
Flowers & ConesC ones are the structures on plants such as
pine cones that contain the seedsFlowers are the seed bearing structures on
plants like oak trees and rose bushes.
PollenPollen is the structure that contains the
sperm of the plant. Pollen can be transferred from one flower to another in several ways. What are some ways that pollen can be transferred?
SeedsSeeds are
multicellular structures that contain the developing embryo of a plant. The seeds also contains a stored food supply for the embryo. A seed coat surrounds and protects the embryo as it grows.
Find video of seed growth
Evolution of Seed PlantsAs landmasses on Earth became dryer seed
plants invaded these areas and eventually become the dominant land plant.
GymnospermsAll members of this group have “naked”
seeds – seeds are not enclosed/protected by fruit.
Gnetophytes – reproductive scales are clustered into cones
GymnospermsCycads – palmlike plants that reproduce
with large cones
GymnospermsGinkgoes – phylum contains only one
extant specie(Ginkgo biloba)
GymnospermsConifers are the most
recognizable and most common gymnosperm
Evolution of ConifersThe specialized leaves (needles) of conifers
are adapted to dry, cool environments. The shape of the needle reduces water loss.They have a thick waxy cuticle on the
surface of the needles that also reduces water loss.
Needles contain a lot of resin which reduces the number of herbivores that will eat them because they taste so bad.
Holes for gas exchange are sunken, this reduces water loss.
Angiosperms - Flowering PlantsThe majority of the members of this
phylum have seeds that are enclosed in fruits. Different flower parts give rise the different parts of the fruit.
Angiosperms - Flowering PlantsFlowers contain the reproductive organs of
angiosperms. What evolutionary advantage does a flower give an angiosperm?
Angiosperms - Flowering PlantsFertilization is when the sperm and egg
unite. During seed development the ovary develops into the fruit.
Angiosperms - Flowering PlantsThe fruit of angiosperms is a wall of tissue
surrounding the seed. Fruits are another evolutionary advantage for the success of this group.
Diversity of AngiospermsMonocots vs. Dicots –
named for the number of seed leaves/cotyledons in the plant embryo. Monoctos have one, Dicots have two
Fig. 22-25
Diversity of AngiospermsMonocots vs. Dicots – (con’t)
Diversity of AngiospermsMonocots vs. Dicots – (con’t)