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Seed-Bearing Plants Vascular Plants

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Seed-Bearing Plants Vascular Plants Seed-bearing Plants Land Plants fall into two major Vascular Plants groups • Non vascular • Vascular • Some are seedless •Others produce seed 1 Seed-bearing Vascular Plants fall Seed-bearing Vascular Plants fall into two major categories into two major categories • Gymnosperm – seeds naked on surface of sporophyll • Angiosperm – seeds enclosed in a ripened ovary Angiosperms Gymnosperms Seed-bearing plants also produce Living Gymnosperms pollen Cycads Conifers Ginkgoes Gnetophytes 2 Cycads Appeared on Earth 250 MYA • Reached their greatest abundance and diversity during the Jurassic • Declined sharply during the Cretaceous radiation of the angiosperms. Global Distribution of Cycads is Mexican Cycads Tropical Dioon Ceratozamia 3 Australian Cycads African Cycads Macrozamia Macrozamia Encephalartos Stangeria Only Cycad Native to the US Cycads – Vegetative Characteristics Zamia pumila Encephalartos in Africa 4 Cycad Stems Cycad Leaves • Columnar • Produced in crowns • Little branching at tip of stem • Not very woody • Pinnately compound Certain roots in Cycads grow A Closer Look at Coralloid Roots toward the soil surface • Grow upward near soil Corraloid surface Roots • Branch to form masses • Root cortex inhabited by Cyanobacteria (carry out nitrogen fixation) 5 Cycads – Reproductive Structures Cycads produce pollen and seeds in cones • Cones develop at apex of stem All Cycads are Dioecious Many Cycads are Pollinated by Insects • Individual plants produce either pollen cones or seed cones Trigona weevils • Only a few cycad species studied • Weevils and oldest known bee genus (Trigona) Pollen Cone • Usually pollinators mate and lay eggs within female cone • All cones except Stangeria produce heat. Thought to Seed Cone volatilize pollinator attractants Cycas revoluta • Hence insect pollination may predate flowering plants 6 Ginkgo – The Maiden Hair Tree Ginkgo was a common forest tree in the geological past • Today represented by a single species • Once occurred in North American Forests • Presently occurs naturally only in China Present Distribution of Ginkgo biloba Ginkgo is also widely cultivated • “Natural” trees may actually be plants cultivated at ancient Monasteries 7 Ginkgo – Vegetative Characteristics Ginkgo is Deciduous Ginkgo is Deciduous Ginkgo Stems • Extensive branching • Very woody 8 Ginkgo Stems Ginkgo Stems long shoot spur shoot long shoot spur shoot Leaf shape ranges from entire Ginkgo Leaves to bilobed • Fan shaped • Dichotomous branching veins 9 Ginkgo produces a seed with a All Ginkgo trees are Dioecious fleshy seed coat • Individual plants produce either pollen “cones” or seed • Seed Coat contains “cones” Butyric Acid • Produced on spur shoots • Seed Coat is not edible C Pollen “Cone” Seed “Cone” Ginkgo seeds are edible when fleshy seed coat is removed 10 Taro with Ginkgo Seed Ginkgo biloba leaves are a popular herbal remedy • Slow the progression of Alzheimer's symptoms • Relieve depression, anxiety, headaches, ringing in the ears (tinnitus), and dizziness • Reduce macular degeneration and control cataracts • Optimize brain power 11 Conifers – the most conspicuous Conifers gymnosperms • Like the Cycads and Ginkgos, Conifers are well represented in the fossil record Sequoia affinis Conifers are of great ecological Conifers are of great ecological importance importance • Conifers are the dominant • Conifers are important members of members of the vast Boreal forests (Taiga) other ecosystems 12 Conifers are of great economic There are seven living families of importance Conifers • Edible Seeds • Crates, Boxes, Matchsticks, Furniture • Telephone Poles • Turpentine and Rosin (Resin) Pines, Fir Spruce Norfolk Island Pines • Fuel (Pitch) • Pulpwood • Ornamentals Five of Sequoias and Redwoods the most • Pharmaceutica familiar ls (Taxol) Yew Junipers and Cedars The Largest and the Oldest Plants are Vegetative Characters of Pine both Conifers • Giant Sequoias of the California Sierras are the largest • Bristlecone pines of the California White Mountains are the oldest 13 Pine Stems Pine Stems • Extensive branching • Wood consist of tracheids • Christmas tree shape only • Very woody • No fibers or vessels • Wood is “soft” Pine Leaves Leaf shape in transverse section • Needles depends on number produced of leaves in the in clusters (fascicles) fascicle of 1 to 5 14 Ginkgo Stems Pine Leaves • Each fascicle is spur shoot an entire long shoot spur shoot spur shoot long shoot Pines produce pollen and seeds in Pine – Reproductive structures cones 15 Pines are Monecious Pines are Monecious Individual plants produce both pollen cones and seed cones Individual plants produce both pollen cones and seed cones Seed Cone Pollen Cone C C Pollen cones produce pollen Seed cones produce seed Young seed cone C C Mature seed cone 16 The Gnetophytes Ephedra is a desert shrub Ephedra Gnetum Welwitschia Ephedra is distributed in arid Ephedra contains Ephedrine regions of the world 50 species 39 species monotypic http://www.anephedraattorneyforyou.com/ 17 Pseudoephedrine is a Synthetic Gnetum is a Version of Ephedrine tropical vine or small tree Gnetum occurs in the tropics Welwitschia is a bizarre plant of an extremely arid environment 50 species 39 species monotypic 18 Welwitschia occurs only in the Welwitschia Namib Desert in South-West Africa forms a short stem and deep tap root 50 species 39 species monotypic Welwitschia Welwitschia produces leaves grow from the base only two – leaves fray adult leaves as they grow 19.
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