Chapter 35 Plants

Biology, 7th Edition (Book & CD-ROM)

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Chapter 35 Plant Structure, Growth, and Development I. Hierarchy of Organs A. Roots 1. Function a. Anchors a vascular plant (usually in the soil) b. Absorbs minerals and water c. Stores organic nutrients 2. Taproot System a. One main vertical root (the tap root) b. Gives rise to lateral roots (branch roots) c. Stores organic nutrients that the plant consumes during flowering and fruit production i This is why carrots, turnips, and sugar beets are harvested before they flower 3. Fibrous root system a. Thin roots spreading out below the soil surface with no root standing out as the main one b. More shallow than a taproot system c. Like grass routs 4. Water adsorption occurs near the root tips a. Tiny root hairs increase surface area 5. Root hairs are an extension of a root epidermal cell, NOT lateral roots B. Stems 1. An organ consisting of an alternating system of nodes (point where leaves are attached) and internodes (segments between nodes) 2. Axillary buds are formed in the angle the stem makes with a leaf. It has the potential to form a branch (lateral root) a. Most are dormant; elongation concentrated near the shoot tip which has a terminal bud 3. Terminal bud a. All the growth happens there, because plant wants to grow up to reach more sunlight b. What if there is no terminal bud or there is more sun towards the sides? i The axillary buds grow into their own lateral roots with stems, terminal buds, and axillary buds of their own ii This is how modified stems were created C. Leaves 1. Function a. Photosynthesis 2. Parts of it a. Flattened blade b. Petiole- joins the leaf to a node of the stem c. Stalk d. Many grasses and monocots lack petioles
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3. Veins a. Monocots- parallel major veins b. Dicot- multibranched network of major veins 4. Modified leaves a. Tendrils i Small skinny leaves that cling to a support in a coil-fashion b. Spines i Spines of a cactus are leaves c. Storage leaves i Modified leaves store water sometimes, as in succulents d. Bracts i Surround a group of flowers to attract pollinators e. Reproductive leaves i Produce plantlets which fall off the leaf and take root in the soil D. Three Tissue Systems 1. Dermal Tissue System a. Is the outer protective covering, forms the first line of defense against damage and pathogenic organisms b. In nonwoody plants it consists of an epidermis i Protects the plant from water loss and disease ii Theirs is a cuticle in the epidermis of leaves and stems c. In woody plants it consists of protective tissue called a periderm 2. Vascular Tissue System a. Carries out long-distance transport of materials between roots and shoots b. Xylem- tissue that conveys water and dissolved minerals upward from roots into shoots c. Phloem- transports organic nutrients such as sugars from where they are made to where they are needed (leaves to rots usually) d. Stele- all the vascular tissue of a root together i In angiosperms the stele of the root is like a vascular cylinder, but the stele of the stems and leaves are divided into vascular bundles
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Chapter 35 Plants - Chapter 35 Plant Structure, Growth, and...

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