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Chapters 29 -30 Plants There are many different species of plants 270,000+ species of plants have been described so far by botanists Why study plants? Provide the Oxygen we breathe Plants provide the Ozone UV screen Food Fossil Fuels Essential oils Wood and paper Jobs Medicine Decoration Habitat Fibers "The Importance of Plants“ reference: Chapter 29 Plants As Food "of the more than 350,000 plant species, people use at least 10,000 species for food." • FOOD CROPS – – – – – cereals root crops legumes fruits, vegetables and nuts spices, herbs, and flavorings • NONFOOD USES OF PLANTS • PLANT ECOLOGY – – – – – medicinal- quinine. aspirin, taxol, echinacea, etc. clothing and fabric dyes fuels anti-erosion fertilizers- crop rotation – – – – food chain - producers oxygen supply plant-animal interactions harmful plants Photosynthesis The process in which plants use H2O, CO2, and light energy to make food (sugars) O2 is released! The most important chemical reaction in the world??? Plant Evolution and Classification reference: chapter 30 • 1st land plants----> simple structure; probably evolved from green algae (Chlorophytes) • Advantages to living on land: light more available CO2 more available at the time = no other competing life forms (no organisms living on land until about 430 mya) • Problems with living on land- must evolve protective features to live on land preventing water loss reproducing by seeds and spores transporting materials throughout body How are plants classified? Botanists group plants to make it easier to study and learn from them Classified based on their traits Tissue structure Seed Structure Size Reproductive characteristics How are plants classified? Vascular- plants that have tube-like cells for transport of materials Non-vascular- no tube-like cells; absorb materials through contact What traits do all plants have in common? What traits do all plants have in common? All plants: •Are multicellular •Cells are eukaryotic •Chlorophyll containing chloroplasts •Stiff cell wall (cellulose) BRYOPHYTES: Non-vascular plants Plants without vascular tissue; cannot transport materials up/down No true roots (hair-like projections called “rhizoids”) Mosses Non-vascular plants get H2O by osmosis Stems and leaves grow close to the ground why? Liverworts Usually grow in damp, shaded environments why? gametes produced in sex structures: archegonia (female) and antheridia (male) spores produced in sacs called "sporangia" (contained in capsules at the plant's tip) Gametophyte is the dominant stage in bryophytes Alternation of Generations in Plants Moss Life Cycle: http://www.su manasinc.com/ webcontent/ani mations/conten t/moss.html Significance of mosses and liverworts? Food/shelter for small animals and insects Hold soil into place (reduce erosion) Used as an nesting material Ecologically important “pioneer” organisms: breakdown of rocks into soil Increase amount of water held: peat moss & houseplants Peat moss is a fuel Vascular plants Vascular plants have true roots, stems, and leaves Xylem- carry water and dissolved nutrients from roots to leaves Phloem- carry sugars made from photosynthesis from leaves to all parts of the plant Vascular plants What advantages do vascular plants have? TRACHEOPHYTES: the vascular plants • Have true leaves, roots, stems • Have support: lignins and fibrous materials • Have a true conducting system for water, food, and minerals – xylem- conducts water and ions from roots to leaves • The conducting elements of xylem are called TRACHEIDS and VESSEL MEMBERS – phloem- carries dissolved sugar and other products of photosynthesis from the leaves to the nonphotosynthetic cells of the plant. • The conducting elements of phloem are called SIEVE CELLS or SIEVE-TUBE MEMBERS Earliest Vascular Plants: Pterophyta, Sphenophyta, etc. Ancient ancestors of the plant world; have been around for ~335 my Includes ferns, horsetails, club mosses Reproduces by spores, rather than seeds Grow taller than mosses and liverworts because of the vascular system one stage of life does not have a vascular system (rhizoids) so ferns like moist, shady places to live over 12,000 species of ferns (~8,000 tropical) The Seed Plants •~300 myo; includes most "modern" plants •have a dominant sporophyte stage •reproduce using pollen (sperm) traveling to egg (ovum) on cones or flowers, which results in SEEDS What are seeds? Part of a plant that contains a new, young plant + stored food Why does any embryo have stored food? Uses of seeds pesticides Milkweed seed extracts used to control roundworm pops. in crops Industrial Castor oil is used to lubricate aircrafts and also as a component in shatterproof glass Food! 3,500 uses for corn alone! spices cosmetics Grape seed extract Neem oil Medicine Flax seed extract Grapefruit seed extract ~herbal medicines decoration THE VASCULAR SEED PLANTS2 groups dominant today • Gymnosperms "naked seed"; ~350 myo, about 700 species today • Angiosperms "flowering plants"; ~135 myo, about 240,000 species today Gymnosperms: • do not have flowers as reproductive structures • Division Cycadophyta: cycads • Division Ginkgophyta: ginkgos • Division Coniferophyta: cone-bearing trees, evergreens, pines; have reducedsized leaves = needles (water conservation) • Division Gnetophyta: some desert plants, like Ephedra Conifers cone-bearing plants most evergreens found mainly in Northern areas of the world sheds leaves like a dog- not all at once! In what part of NJ would you find a lot of conifers? Conifers Has anyone ever noticed that a pine tree has 2 different cones on it? Female and Male Cones Conifers Some conifers do not have woody cones Yews have red, fleshy cones that birds love to eat! The birds spread the seeds via their digestive system Conifers are important! Produce 50-75% of the world’s lumber & paper pulp Important to other animals for food and shelter (Northern Spotted Owl) Turpentine (from sap) Taxol (cancer drug from Yew bark) Christmas trees California redwoods..Sequoia Yosemite National Park The Angiosperms: Flowering plants Angiosperm (“closed seed”) Produce flowers and form fruit containing seeds More flowering plants than non-flowering plants (~230,000 flowering plants); Very successful! Reasons? Plants flower at different times of the year Flowering plants- life cycle Generalized life cycle of flowering plants Flower Types Rafflesia arnoldi Wolffia angusta Titan arum Two classes of Angiosperms • Monocots, Dicots • "cotyledon" : the embryonic seed leaf Differences between monocot/dicot species: DICOTS: -two embryonic seed leaves -Dicots contain vascular bundles in the stem in the form of a ring -Leaves have a networklike venation in dicots (also usually broad, wide leaves) -Dicots have a taproot system (main central root) -Dicots have flowers in groups of 4 or 5 petals MONOCOTS: -Single embryonic seed leaf -Monocot leaves are tapered w/ parallel venation -Monocots have a fibrous root system (close to surface) -Vascular bundles are scattered in a monocot stem -Monocots have flowers w/ groups of 3 petals Difference between monocot/dicot species: