Biology Sylvia S. Mader Michael Windelspecht Chapter 24 Flowering Plants: Structure and Organization Lecture Outline See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1

Biology, 9th ed, Sylvia Mader Chapter 25 Outline Structure and Organization of Plants 24.1 Organs of Flowering Plants 24.2 Tissues of Flowering Plants 24.3 Organization and Diversity of Roots 24.4 Organization and Diversity of Stems 24.5 Organization and Diversity of Leaves

24.1 Organs of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 25 24.1 Organs of Flowering Plants Structure and Organization of Plants Flowering plants, or angiosperms, are extremely diverse but share many common structural features. Most flowering plants possess a root system and a shoot system The root system simply consists of the roots, The shoot system consists of the stem and leaves. A typical plant features three vegetative organs roots, stems, and leaves Vegetative organs are concerned with growth and nutrition. Flowers, seeds, and fruits are structures involved in reproduction.

Organization of Plant Body Biology, 9th ed, Sylvia Mader Organization of Plant Body Chapter 25 Structure and Organization of Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. terminal bud blade leaf vein petiole axillary bud stem node internode node vascular tissues shoot system root system branch root root hairs primary root

Organs of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 25 Organs of Flowering Plants Structure and Organization of Plants Roots Generally, the root system is at least equivalent in size and extent to the shoot system Anchors plant in soil Absorbs water and minerals from the soil Produces hormones Root hairs: Projections from epidermal root-hair cells Greatly increase absorptive capacity of root

Organs of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 25 Organs of Flowering Plants Structure and Organization of Plants 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 Axillary buds can produce new branches of the stem (or flowers) Stem also has vascular tissue that transports water and minerals

Organs of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 25 Organs of Flowering Plants Structure and Organization of Plants Leaves major part of the plant that carries on photosynthesis Foliage leaves are usually broad and thin Blade - Wide portion of foliage leaf Petiole - Stalk attaching blade to stem Leaf Axil - Upper acute angle between petiole and stem where the axillary bud is found Tendrils - Leaves that attach to objects Bulbs - Leaves that store food

Vegetative Organs of Several Eudicots Biology, 9th ed, Sylvia Mader Chapter 25 Vegetative Organs of Several Eudicots Structure and Organization of Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. blade petiole stems stem roots lateral root a. Root system, dandelion b. Shoot system, bean seedling c. Leaves, pumpkin seedling a: © Dorling Kindersley/Getty Images; b:© Dwight Kuhn; c: © Dwight Kuhn

Organs of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 25 Organs of Flowering Plants Structure and Organization of Plants Monocots (Single cotyledon) Cotyledons act as transfer tissue Nutrients are derived from the endosperm Root vascular tissue occurs in ring Parallel leaf venation Flower parts arranged in multiples of three Eudicots (Two cotyledons) Cotyledons supply nutrients to seedlings Root phloem located between xylem arms Netted leaf venation Flower parts arranged in multiples of four or five

Flowering Plants are Either Monocots or Eudicots Biology, 9th ed, Sylvia Mader Chapter 25 Flowering Plants are Either Monocots or Eudicots Structure and Organization of Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Seed Root Stem Leaf Flower Monocots Root xylem and phloem in a ring Vascular bundles scattered in stem Leaf veins form a parallel pattern Flower parts in threes and multiples of three One cotyledon in seed Eudicots Root phloem between arms of xylem Vascular bundles in a distinct ring Leaf veins form a net pattern Flower parts in fours or fives and their multiples Two cotyledons in seed

24.2 Tissues of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 25 24.2 Tissues of Flowering Plants Structure and Organization of Plants Meristematic tissue enables flowering plants to grow throughout their lifetime Apical meristems at the tips of stems and roots increase the length of these tissues Apical meristem produces three types of meristem, which produce three specialized tissues Epidermal tissue Ground tissue Vascular tissue

Tissues of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 25 Tissues of Flowering Plants Structure and Organization of Plants Epidermal Tissue Forms the outer protective covering of a plant Epidermis contains closely packed epidermal cells Epidermal cells exposed to air are covered with waxy cuticle Root epidermal cells have root hairs Epidermal cells of stems, leaves, and reproductive organs have trichomes Lower leaf surface contains stomata In older woody plants, the epidermis of the stem is replaced by periderm Major component is cork New cork is made by cork cambium 12

Modifications of Epidermal Tissue Biology, 9th ed, Sylvia Mader Modifications of Epidermal Tissue Chapter 25 Structure and Organization of Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. corn seedling guard cell chloroplasts periderm lenticel cork cambium cork root hairs enlongating root tip nucleus Stoma a. Root hairs b. Stoma of leaf c. Cork of older stem a: © Evelyn Jo Johnson; b: © J.R. Waaland/Biological Photo Service; c: © Kingsley Stern

Tissues of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 25 Tissues of Flowering Plants Structure and Organization of Plants Ground tissue forms bulk of a flowering plant Parenchyma cells: Least specialized and are found in all organs of plant Can divide and give rise to more specialized cells Collenchyma cells: Have thicker primary walls Form bundles underneath epidermis Provide flexible support for immature regions of the plant

Tissues of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 25 Tissues of Flowering Plants Structure and Organization of Plants Ground tissue (continued) Sclerenchyma cells: Have thick secondary walls impregnated with lignin Most are nonliving Primary function is to support mature regions of the plant Two types of sclerenchyma cells Fibers Sclereids

Tissues of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 25 Tissues of Flowering Plants Structure and Organization of Plants Vascular Tissue Xylem transports water and minerals from the roots to the leaves Tracheids Long, with tapered ends Water moves across pits in end walls and side walls Vascular rays between rows of tracheids conduct water across the width of the plant Vessel Elements Larger, with perforated plates in their end walls Form a continuous vessel for water and mineral transport

Biology, 9th ed, Sylvia Mader Chapter 25 Xylem Structure Structure and Organization of Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. vessel element vessel element tracheid tracheids perforation plate pitted walls xylem parenchyma cell pits 50 mm a. Xylem micrograph (left) and drawing (to side) b. T wo types of vessels c. T racheids a: © J. Robert Waaland/Biological Photo Service

Tissues of Flowering Plants Biology, 9th ed, Sylvia Mader Chapter 25 Tissues of Flowering Plants Structure and Organization of Plants Vascular Tissue Phloem transports sucrose and other organic compounds from the leaves to the roots Sieve-tube members function as conducting cells Contain cytoplasm, but lack nuclei Sieve plate – cluster of pores in wall Each sieve-tube member has a companion cell Plasmodesmata connect the two Companion cell contains a nucleus

Biology, 9th ed, Sylvia Mader Chapter 25 Phloem Structure Structure and Organization of Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. sieve plate sieve-tube member sieve-tube member companion cell companion cell sieve plate nucleus phloem parenchyma cells 20 mm a. Phloem micrograph (left) and drawing (to side) b. Sieve-tube member and companion cells a: © George Wilder/Visuals Unlimited

24.3 Organization and Diversity of Roots Biology, 9th ed, Sylvia Mader Chapter 25 24.3 Organization and Diversity of Roots Structure and Organization of Plants Root cap contains root apical meristem Zone of cell division contains primary meristems Zone of elongation contains cells that are lengthening and becoming specialized Zone of maturation contains fully differentiated cells

Organization and Diversity of Roots Biology, 9th ed, Sylvia Mader Chapter 25 Organization and Diversity of Roots Structure and Organization of Plants Tissues of a Eudicot Root: Epidermis - outer layer of root Cortex – composed of parenchyma cells allowing water and minerals movement Endodermis – forms a boundary between cortex and inner vascular cylinder Casparian strip Vascular Tissue - contains xylem and phloem Pericycle – mitotically active and can begin development of branch or lateral roots

Biology, 9th ed, Sylvia Mader Eudicot Roots Chapter 25 Structure and Organization of Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Vascular cylinder endodermis pericycle phloem xylem cortex epidermis root hair 50 µm b. Vascular cylinder phloem Zone of maturation endodermis water and minerals Casparian strip xylem of vascular cylinder pericycle Zone of elongation c. Casparian strip procambium ground meristem Zone of cell division protoderm root apical meristem protected by root cap root cap a. Root tip a: Courtesy Ray F. Evert/University of Wisconsin Madison; b: © CABISCO/Phototake

Organization and Diversity of Roots Biology, 9th ed, Sylvia Mader Chapter 25 Organization and Diversity of Roots Structure and Organization of Plants Monocot roots: Ground tissue of root’s pith is surrounded by vascular ring Have the same growth zones as eudicot roots, but do not undergo secondary growth Have pericycle, endodermis, cortex, and epidermis

Organization and Diversity of Roots Biology, 9th ed, Sylvia Mader Chapter 25 Organization and Diversity of Roots Structure and Organization of Plants Primary root (taproot) - Fleshy, long single root, that grows straight down Stores food Fibrous root system - Slender roots and lateral branches Anchors plant to soil Adventitious roots - Roots develop from organs of the shoot system instead of the root system Prop roots

Organization and Diversity of Roots Biology, 9th ed, Sylvia Mader Chapter 25 Organization and Diversity of Roots Structure and Organization of Plants Haustoria: Found in parasitic plants Rootlike projections that grow into host plant Make contact with vascular tissue of the host plant and extract water and nutrients Mycorrhizae: Mutualistic associations between roots and fungi Assist in water and mineral extraction Root nodules Contain nitrogen-fixing bacteria

Biology, 9th ed, Sylvia Mader Stem Diversity Chapter 25 Structure and Organization of Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. rhizome branch axillary bud papery leaves adventitious roots stolon corm node axillary bud rhizome adventitious roots tuber adventitious roots a. Stolon b. Rhizome c. Tuber d. Corm a: © The McGraw-Hill Companies Inc./Evelyn Jo Johnson, photographer; b: © Science Pictures Limited/Photo Researchers, Inc.; c: © The McGraw Hill Companies, Inc./Carlyn Iverson, photographer; d: © The McGraw Hill Companies, Inc./Carlyn Iverson, photographer

24.5 Organization and Diversity of Leaves Biology, 9th ed, Sylvia Mader Chapter 25 24.5 Organization and Diversity of Leaves Structure and Organization of Plants Leaves contain: Upper and lower epidermis Waxy cuticle Trichomes Lower epidermis has stomata for gas exchange Mesophyll Eudicot leaves have Palisade mesophyll containing elongated cells Spongy mesophyll containing irregular cells bounded by air spaces Contains many chloroplasts 27

Biology, 9th ed, Sylvia Mader Chapter 25 Leaf Structure Structure and Organization of Plants Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. trichomes Water and minerals enter leaf through xylem. cuticle upper epidermis Sugar exits leaf through phloem. palisade mesophyll bundle sheath cell air space spongy mesophyll lower epidermis cuticle leaf vein stoma chloroplast central vacuole upper epidermis epidermal cell nucleus chloroplast palisade mesophyll O2 and H2O exit leaf through stoma. nucleus leaf vein guard cell CO2 enters leaf through stoma. spongy mesophyll mitochondrion stoma lower epidermis Leaf cell Stoma and guard cells 100 m SEM of leaf cross section © Jeremy Burgess/SPL/Photo Researchers, Inc.

Organization and Diversity of Leaves Biology, 9th ed, Sylvia Mader Chapter 25 Organization and Diversity of Leaves Structure and Organization of Plants Leaf Diversity Blade of a leaf can be simple or compound Leaves are adapted to environmental conditions Shade leaves Spines Climbing leaves