1. Introduction to Seed Plants: Gymnosperms
Chapter 22
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2. Human Relevance of Gymnosperms Conifers Other Gymnosperms
Outline
Overview
Phylum Pinophyta
Phylum Ginkgophyta
Phylum Cycadophyta
Phylum Gnetophyta
Human Relevance of Gymnosperms
Conifers
Other Gymnosperms
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3. Gymnosperm refers to the exposed nature of the seeds.
Overview
Gymnosperm refers to the exposed nature of the seeds.
Produced on the surface of sporophylls or similar structures instead of being enclosed within a fruit as in flowering plants.
Female gametophyte is produced inside an ovule that contains a nucellus.
Enclosed in integument.
Four living Phyla
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4. Exposed versus Enclosed Seeds
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5. Largest genus of conifers. Over 100 living species.
Phylum Pinophyta
The Conifers
Pines
Largest genus of conifers.
Over 100 living species.
Include world’s oldest known living organisms (Bristlecone Pines).
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6. Structure and Function
Phylum Pinophyta
Structure and Function
Pine leaves are needlelike and are arranged in clusters of bundles of two to five leaves.
Each cluster (fascicle) forms a cylindrical rod if the leaves are held together.
Hypodermis located below the epidermis.
Resin canals develop in mesophyll.
Antiseptic and Insect Deterrent.
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7. Pine Stem Cross Section
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8. Most wood varies considerably in hardness.
Phylum Pinophyta
Most wood varies considerably in hardness.
Most gymnosperm wood consists primarily of tracheids.
No vessel members or fibers.
Soft Wood
Mycorrhizal fungi associated with the roots of most conifers.
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9. Pine Life Cycle
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10. Pine Life Cycle
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11. Pine Ovule - Longitudinal Section
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12. Ginkgo (Maidenhair Trees) Only one living species.
Phylum Ginkgophyta
Ginkgo (Maidenhair Trees)
Only one living species.
Notched, broad, fan-shaped leaves.
Leaves are produced in a spiral on short, slow-growing spurs.
No midrib or prominent veins.
Hair-like veins branch dichotomously.
Life cycle similar to pines.
Dioecious
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13. Appearance of a cross between a tree fern and a palm.
Phylum Cycadophyta
The Cycads
Appearance of a cross between a tree fern and a palm.
Slow-growing plants of the tropics that have tall unbranched trunks.
Crown of largely pinnately divided leaves.
Life Cycle similar to conifers.
Pollination is generally brought about by beetles instead of wind.
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14. Unique among the gymnosperms in having vessels in the xylem.
Phylum Gnetophyta
The Gnetophytes
Unique among the gymnosperms in having vessels in the xylem.
More than half of the 70 known species are joint firs in the genus Ephedra.
Most of remaining species are in genus Gnetum.
Occur in tropics
Most are vine-like with broad leaves similar to those of flowering plants.
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15. Third genus, Welwitschia, has only one species.
Phylum Gnetophyta
Third genus, Welwitschia, has only one species.
Confined to temperate deserts of southwestern Africa.
Average rainfall only 2.5 cm.
Plant use CAM photosynthesis.
Only produce two leaves throughout their life span.
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16. Human Relevance of Gymnosperms
Conifers
Edible Seeds
Crates, Boxes, Matchsticks, Furniture
Telephone Poles
Turpentine and Rosin (Resin)
Fuel (Pitch)
Pulpwood
Ornamentals
Pharmaceuticals (Taxol)
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17. Human Relevance of Gymnosperms
Other Gymnosperms
Ginko Seeds - Food
Ephedra - Mormon tea
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18. Human Relevance of Gymnosperms Conifers Other Gymnosperms
Review
Overview
Phylum Pinophyta
Phylum Ginkgophyta
Phylum Cycadophyta
Phylum Gnetophyta
Human Relevance of Gymnosperms
Conifers
Other Gymnosperms
Stern - Introductory Plant Biology: 9th Ed. - All Rights Reserved - McGraw Hill Companies

19. Copyright © McGraw-Hill Companies Permission Required for Reproduction or Display
Stern - Introductory Plant Biology: 9th Ed. - All Rights Reserved - McGraw Hill Companies