Chapter 24 Seed Plants: Gymnosperms PDF

Chapter 24 Seed Plants: Gymnosperms Ch 24 Learning Objectives 1. 2. 3. 4. 5. 6. 7. 8. Compare the features of seeds with those of spores and discuss the adaptive advantages of plants who reproduce via seeds. Distinguish between an ovule and a seed and define the integuments. Summarize the features t...

Chapter 24 Seed Plants: Gymnosperms Ch 24 Learning Objectives 1. 2. 3. 4. 5. 6. 7. 8. Compare the features of seeds with those of spores and discuss the adaptive advantages of plants who reproduce via seeds. Distinguish between an ovule and a seed and define the integuments. Summarize the features that distinguish gymnosperms from seedless vascular plants. Name and briefly describe the four phyla of gymnosperms. Contrast monoecious plants from dioecious plants. Know the steps of the pine life cycle and compare the sporophyte generations from the gametophyte generation. Describe the ecological and economic significance of gymnosperms. Trace the evolution of gymnosperms from the seedless vascular plants. Evolutionary History of Plants ❖ Adaptations needed to live in a terrestrial environment? Ways to obtain nutrients and water? Ways to keep water and stop desiccation? Ways to get enough but not too much sunlight? Ways to get CO2 and release O2? Ways to structurally support the body? Ways to protect and spread offspring? ❖ Oldest known seeds - Late Devonian, more than 350 million years ago ❖ Gymnosperms dominate during the Triassic, ~200-250 mya ❖ First seed plants are fernlike in appearance: pteridosperms (seed ferns) - Reclassified as Gymnosperms Gymnosperm General Characteristics ❖ Small taxa: 4 phyla w/ 73 genera and ~700 species Phyla: – Coniferophyta – Conifers – Cycadophyta - Cycads – Ginkgophyta – Ginkgo biloba – Gnetophyta - gnetophytes Gametophyte Stage becoming Reduced Bryophytes Seedless Vascular Plants Seeded Vascular Plants Gymnosperms Angiosperms 10 Gymnosperm General Characteristics cont. ❖ Vascular Tissue (Xylem and Phloem) Gymnosperm xylem: – tracheids (Coniferophyta, Cycadophyta, Gingkophyta, and Gnetophyta) – vessel elements: (Gnetophyta) Tracheids Vessel elements Gymnosperm General Characteristics cont. ❖ Vascular Tissue (Xylem and Phloem) Wood (secondary xylem) – Manoxylic: soft and loose w/ high parenchyma cells - Cycads – Pycnoxylic: high xylem, stronger o Conifers and Angiosperms Gymnosperms – “Naked” Seeds Cycad seed cone Pinus sp. Gingko seeds Welwitschia sp. seed ❖ Pollen (staminate) cones (male strobili) house the microspores that grow into pollen grains (male gametophyte). Pinus sp. Pinus sp. Cycad Pinus sp. ❖ Female (ovulate) cones (strobili) produce the megaspore that will grow into the female gametophyte that produces the archegonia and ovule that will be fertilized and become a seed Pinus sp. Pinus sp. Cycad Seed Plant Classification ❖ Superdivision: Spermatophyta (Tracheophyta) Phylum Coniferophyta (Pinophyta) – Conifers Phylum Ginkgophyta – Ginkgo biloba Phylum Cycadophyta – Cycads Phylum Gnetophyta – Gnetophytes Note: Division = Phylum Seed Plant Classification ❖ Superdivision: Spermatophyta (Tracheophyta) Phylum Coniferophyta (Pinophyta) – Conifers Phylum Ginkgophyta – Ginkgo biloba Phylum Cycadophyta – Cycads Phylum Gnetophyta – Gnetophytes Note: Division = Phylum Blue Spruce Phylum Coniferophyta Pine Eastern Hemlock Conifers of the Taiga Phylum Coniferophyta– Conifers ❖ Pines (Pinus sp.)-largest genus Mostly monoecious – Include world’s oldest known living organisms - Bristlecone pines Phylum Coniferophyta–Conifers ❖ Pines (Pinus sp.): needle like leaves Phylum Coniferophyta–Conifers: Scale like leaves Pinus sp. Life Cycle Immature microgametophyte (n) → pollen grain Pinus sp. Life Cycle Phylum Coniferophyta – Pinus sp. Pollen w/pollen tube Phylum Coniferophyta: Pinus sp. Phylum Coniferophyta: Pinus sp. Perisperm Taxus sp. Torreya sp. Podocarpus sp. Phylum Coniferophyta: Other Conifers Juniperus sp. Seeded Vascular Plants: Gymnosperms: Coniferophyta Seeded Vascular Plants: Gymnosperms: Coniferophyta ❖ Giant Sequoia (Sequoiadendron giganteum) Smaller Sequoia Footprint of the Base of General Sherman Other Conifers ❖ NC Native: Bald Cypress (Taxodium distichum) Deciduous = looses needles in winter ❖ Native to our region: Bald Cypress (Taxodium distichum) ❖ Confers native to our region: ❖ Longleaf Pine (Pinus palustrius) ❖ Confers native to our region: Loblolly Pine (Pinus taeda) ❖ Confers native to our region: Eastern Red Cedar (Juniperus virginiana) ❖ Confers native to Western NC: Frasier Fir (Abies fraseri) ❖ Uses of Pine Lumber Horticulture Vitamins A and C from needles Pine Nuts (edible) Fragrance Turpentine Pine Ethnobotany of Gymnosperms ❖ Conifers Edible inner bark and needles of white pine, and seeds of nearly all pines Masts in sailing vessels Crates, boxes, matchsticks, furniture Telephone poles, railroad ties, mine timbers Turpentine and rosin (both from resin) Fuel Pulpwood Construction lumber Ornamentals Pharmaceuticals Seed Plant Classification ❖ Superdivision: Spermatophyta (Tracheophyta) Phylum Coniferophyta (Pinophyta) – Conifers Phylum Ginkgophyta – Ginkgo biloba Phylum Cycadophyta – Cycads Phylum Gnetophyta – Gnetophytes Note: Division = Phylum A Phylum Ginkgophyta (Ginkgo biloba) C B Ovulate organ Fleshy Covered Seeds D E G Male strobili H F Seed Plant Classification ❖ Superdivision: Spermatophyta (Tracheophyta) Phylum Coniferophyta (Pinophyta) – Conifers Phylum Ginkgophyta – Ginkgo biloba Phylum Cycadophyta – Cycads Phylum Gnetophyta – Gnetophytes Note: Division = Phylum Phyla Cycadophyta Phylum Cycadophyta – The Cycads Male cycad Female cycad Phylum Cycadophyta Cycad seed cone Seed Plant Classification ❖ Superdivision: Spermatophyta (Tracheophyta) Phylum Coniferophyta (Pinophyta) – Conifers Phylum Ginkgophyta – Ginkgo biloba Phylum Cycadophyta – Cycads Phylum Gnetophyta – Gnetophytes Note: Division = Phylum Phylum Gnetophyta ❖ Gnetum sp. 3 living genera, ~70 species ❖ Very morphologically diverse Welwitschia sp Ephedra sp. Phylum Gnetophyta ❖ Unique among the gymnosperms in having vessels in the xylem. Male strobili ❖ Joint firs (Ephedra) - Shrubby plants of drier regions of southwestern North America Female strobilus Ephedra Phylum Gnetophyta ❖ Gnetum - Vine-like plants with broad leaves in tropics Gnetum sp. Male Cone Phylum Gnetophyta: Welwitschia sp. Female Cone Ethnobotany of Gymnosperms ❖ Other Gymnosperms Ginkgo biloba: – Seeds for food (after seed coat removal) – Ginkgo extracts to increase blood circulation Ephedra sp.- Mormon tea – Drug ephedrine for respiratory problems from a Chinese species Questions??? Supplemental Videos https://www.youtube.com/watch?time_continue=97&v=D9byVQx vMXs&feature=emb_logo https://www.youtube.com/watch?v=WPfRV8NWkk4