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Plant Structure. Chapter 25. Plant Organs Roots Stems Leaves Monocots vs. Eudicots. Epidermal Tissue Vascular Tissue. Outline. Plant Organs. Roots Anchors plant in soil Absorbs water and minerals Produces hormones that stimulate growth of stems Root hairs:
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Plant Structure Chapter 25 Plant Structure and Organization
Plant Organs Roots Stems Leaves Monocots vs. Eudicots Epidermal Tissue Vascular Tissue Outline Plant Structure and Organization
Plant Organs • Roots • Anchors plant in soil • Absorbs water and minerals • Produces hormones that stimulate growth of stems • Root hairs: • Projections from epidermal root hair cells • Greatly increase absorptive capacity of root Plant Structure and Organization
Organization of Plant Body Plant Structure and Organization
Vegetative Organs of Several Eudicots Plant Structure and Organization
Stems • Shoot system of a plant is composed of the stem, branches, and leaves • Stem is the main axis of a plant that elongates and produces leaves • Nodes occur where leaves are attached to the stem • Internode is region between nodes • Stem also has vascular tissue that transports water and minerals • Can grow in width as well as length (woody tissue) Plant Structure and Organization
Leaves • Leaves are the major part of the plant for photosynthesis • Foliage leaves are usually broad and thin • Blade - Wide portion of foliage leaf • Petiole - Stalk attaches blade to stem • Leaf Axil - Axillary bud originates • Tendrils - Leaves that attach to objects • Bulbs - Leaves that store food Plant Structure and Organization
Monocot vs. Eudicot • Monocots (Single cotyledon) • Cotyledons act as transfer tissue only • Endosperm provides embryo with nutrients • Root vascular tissue occurs in ring • Stem vascular tissue is scattered randomly • Parallel leaf venation (veins) • Flower petals in multiples of 3 • Ex: orchids, lilies, corn, palms, wheat, grass Plant Structure and Organization
Monocot vs. Eudicot • Eudicots (Two cotyledons) • Cotyledons supply nutrients to seedlings • Root vascular tissue in a star shape in center • Root phloem located between xylem arms • Stem vascular tissue occur in a ring • Netted leaf venation (veins) • Flower petals in multiples of 4 or 5 • Ex: dandilions, oak trees, roses Plant Structure and Organization
Flowering Plants:Monocots or Eudicots Plant Structure and Organization
Plant Tissues • Epidermal Tissues • Outer layer of the plant • Contain closely packed epidermal cells • Covered with waxy cuticle • Roots contain root hairs • Lower leaf surface contain stomata • Woody plants covered by cork Plant Structure and Organization
Modifications of Epidermal Tissue Plant Structure and Organization
Ground Tissue • Ground tissue forms bulk of a plant • Parenchyma cells: • Least specialized and are found in all organs of plant • Can divide and give rise to more specialized cells • Ex: roots that develop from cut stems • Collenchyma cells: • Have thicker primary walls • Form bundles underneath epidermis • Flexible support to immature regions of the plant Plant Structure and Organization
Ground Tissue • Sclerenchyma cells: • Have thick secondary walls full of lignin for support • Most are nonliving • Primary function is to support mature regions of the plant • Fibers • Most are in vascular tissue • Sclereids • Shorter & varied In shape • Found in seed coats and nutshells Plant Structure and Organization
Ground Tissue Cells Plant Structure and Organization
Vascular Tissue • Xylem transports water and minerals from the roots to the leaves • Tracheids • Long, hollow, non living schlerencyma cells with tapered ends • Pits in ends and walls for water to pass • Vascular rays transport across the width of the plant • Fibers are present for support • Vessel Elements • Larger, with perforated plates in their end walls for continuous transport Plant Structure and Organization
Xylem Structure Plant Structure and Organization
Vascular Tissue • Phloem transports sucrose and other organic compounds from the leaves to the roots • Sieve-tube members are conducting cells • Contain cytoplasm but no nuclei • Channels in end walls • Plasmodesmata extend from one cell to another through sieve plate Plant Structure and Organization
Phloem Structure Plant Structure and Organization