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Transcript
Plant Anatomy Basic plant anatomy 1 A. root – root tip-roots grow at the tip – root hairsincrease absorptive surface area Roots 1 • Roots anchor plant in soil, absorb minerals & water, & store food – fibrous roots (1) • mat of thin roots that spread out • monocots – tap roots (2) • 1 large vertical root • also produces many small lateral, or secondary roots • dicots – root hairs (3) • increase absorptive surface area 2 3 Basic plant anatomy 2 B. shoot (stem) – Nodes-where leaves attach • Internodes-space between nodes – Buds • Meristems are where plant shoots grow • terminal or apical buds at top of stem • axillary buds- at base of leaf on stem • flower buds-produce flowers Basic plant anatomy 3 C. leaves – Cuticle- waterproof layer – Epidermis- covers top & bottom surface – mesophyll tissue • Palisade- columnar cells, with choloroplasts just below upper epidermis • Spongy- irregularly shaped cells with air spaces between them below palisade – veins (vascular bundles) Leaves • Function of leaves – photosynthesis • Traps solar energy • Produces sugars (food) – gas exchange- occurs through pores called stomates • Guard cells open or close stomates-depends on water – Transpiration- water loss through the stomates Plant adaptations 1. Roots– Tap root-used for food storage (carrot) 2. Stems -rhizomes (iris) & stolons (strawberry)- used to make new plants - tubers- (potato) used for storage - Bulbs- (onion) buds used for storage & new plants Plant adaptations 3. Leaves • CAM & C4-photosynthesis- chemical adaptation for plants in hot climates • Enlarged darker leaf-jungle plants-low light • Spines & poisons- defense against herbivores • Thickened leaf- water storage • Tendrils- climbing plants- attach & support • Bright colors- leaves doing job of petals Modified shoots stolons (strawberries) tuber (potato) rhizome (ginger) bulb (onion) Modified leaves tendrils (peas) succulent leaves spines (cacti) colored leaves (poinsetta) Interdependent systems • Both systems depend on the other – roots need sugars produced by photosynthetic leaves – shoots need water & minerals absorbed by roots sugars water & minerals Vascular tissues • Xylem – move water & minerals up from roots – dead at maturity • only cell walls remain • transpirational pull hauls water up from roots vessel elements vessel element dead cells tracheids sieve tube companion cell sieve plate plasmodesmata living cells Phloem: food-conducting cells • carry sugars & nutrients throughout plant • sieve tube elements – Living at maturity – Keep cell membrane & cytoplasm – lose their nucleus & organelles – sieve plates — end walls — have pores to allow flow of food between cells • companion cells- attached to sieve tubes – run the cell- have nucleus & cell structures Vascular tissue in stems dicot monocot trees & shrubs grasses & lilies collect annual rings Putting it all together • Obtaining raw materials – sunlight • leaves = solar collectors – CO2 • stomates = gas exchange – H2O • uptake from roots – nutrients • uptake from roots Growing Cycles • Perennials - live several years, and reproduce many times Ex. woody plants • Annuals - plant that completes its life cycle in one growing season (grows, flowers, reproduces and dies) • Biennials - take two growing seasons to complete, reproduces in the second growing season Growing Cycles • Plants grow only at their tips in regions called MERISTEMS (length) & cambiums (width) • PRIMARY GROWTH makes a plant taller at roots and stems • SECONDARY GROWTH makes a plant wider, or adds woody tissue How Old Is That Tree? • Tree Rings tell age of a tree, one ring for each growing season.This tree is 4 yrs old. – Spring wood- lighter colored, larger tubes – Summer wood -darker colored, narrower tubes • VASCULAR CAMBIUM: makes xylem and phloem and forms the annual rings Comparison of Monocots & Dicots Monocots & dicots • Angiosperm are divide into 2 classes – dicots (eudicot) • 2 cotyledons (seed leaves) • leaves with network of veins • woody plants, trees, shrubs, beans – monocots • 1 cotyledon • leaves with parallel veins • grasses, palms, lilies Simple Tissues – consisting of one cell type • Parenchyma – thin walled & alive at maturity; cells take different shapes. (storage, can change into other cells) • Collenchyma – thick walled & alive at maturity (support) • Sclerenchyma – thick walled and dead at maturity (support) – Sclerids or stone cells – cells that are as long as they are wide, very heavy cell walls – Fibers – cells longer than they are wide • Epidermis – alive at maturity – Trichomes – hairs on epidermis – Root Hairs – tubular extensions of epidermal cells