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Transcript
Roots, Stems, Leaves, & Flowers Notes I. Roots Roots A. Functions • Absorb water and minerals. • Transport water up to the stem. • Store water and food. • Anchor. B. Parts 1. Xylem • X shaped • center of the root = vascular tissue that transports water up to the stems. 2. Phloem =vascular tissue that transports food down from the leaves and stems. • Roots have 4 bundles of phloem found in the “corners” of the xylem. 3. Cambium = Growth tissue that produces new xylem and phloem. • Found between the xylem and phloem. 4. Cortex • outside ring. • Stores food and water. 5. Root Hairs = single-celled extensions on the root whose purpose is absorbing water. 6. Root tips • Cap = hard tip that pushes through soil. • Apical Meristem Meristem = Plant growth tissue. C. two types of root systems 1. Taproot system • composed of a few large roots examples: carrot, tree. 2. Fibrous root system • composed of a mat of tiny roots. Example: grass D. Mycorrhiza = mutualism = fungus and plant roots E. Adventitious roots = roots that arise from some place other than the primary root. F. Perennial roots = root system that survives from year-to-year as top of the plant is annually dormant. G. Root Foods • Carrots • Radishes II. Stems A. Functions • Transport materials between roots and leaves. • Support leaves and flowers. B. Parts • Xylem • Phloem • Cambium/Meristem herbaceous = a plant that is soft, green, and has a thin bark. C. Types of Stems 1. Herbaceous monocot stem • vascular bundles are scattered. 2. Herbaceous dicot stem • vascular bundles form a circle. 3. Woody stem • contains wood • brown • tough • thick bark http://www.mhhe.com/biosci/pae/botany/histology/html/woodsmic.htm D. Food Stems 1. Potatoes are called tubers. • Swollen tip of an underground stem. 2. Onions are called bulbs. • Small stem surrounded by thick, juicy leaves. 3. Celery is a stem. III. Leaves 1. Function • Photosynthesis! • Transport Food • Store Food 2. Parts A. Cuticle =waxy, waterproof covering. – Not made of cells. B. Upper Epidermis – like skin. – made of cells. C. Lower Epidermis – Stomata = holes that let CO2 in and H2O out. – Guard Cells = cells that surround the stomata. – Transpiration = plants release water from stomata. D. Palisade Layer – long, tall cells found under the upper epidermis. – Lots of chloroplasts! – Most photosynthesis occurs here! E. Spongy Layer – Loose cells with lots of air space. F. Veins • Xylem – Bring water into the leaf. – Top of the vein. • Phloem – Takes sugar from the leaf. – Bottom of the vein. 3. Turgor =pressure of water inside a plant cell – Causes the cell membrane to press against the cell wall. – Causes the cell to be stiff. – High Turgor causes the leaf to be rigid. – Low Turgor causes the leaf to be wilted. IV. Flowers A. Function of Flowers • Flowers are for sexual reproduction. • Flowers produce seeds and fruit. B. Parts of a Flower 1. Pistil = female reproductive structure. The Pistil contains three main parts: a. Stigma = top of the pistil where the pollen sticks. b. Style = stalk c. Ovary =bottom of the pistil. =produces ovules – Ovules are the female gametophytes. 2. Stamen = male reproductive structure • Produces pollen • Pollen is the male gametophyte • 2 parts (1) Filament = stalk (1) Anther = pollen producing sac 3. Petals • Modified leaves • Often Colorful • Often attracts pollinators • Often produces nectar • Protect the developing reproductive organs 4. Sepals • Modified leaves • Often green • Protect the un-opened flower C. Pollination = the transfer of the pollen from an anther to a stigma. • Birds • Bees • Wind D. Fertilization = Fusing of the male and female gamete. • Flowers undergo double fertilization • The results are the zygote and the endosperm. E. Fruit = ripened ovary = if it contains seeds in an ovary wall, it is a fruit. F. Seed Dispersal • Tasty fruits and seeds are eaten and deposited in a nice pile of “fertilizer” • Stickery fruits hang on to fur and britches • Aerodynamic fruits are blown • Floaty fruits disperse by water