Plant Science Plant Structures Instructional Materials Service Texas

Plant Science Plant Structures Instructional Materials Service Texas A&M University - 8384 - 1

Plant Structures § § § Parts of a Vascular Plant Root Structure Stem Structure (External) Leaf Structure Parts of a Complete Flower 2

Plant Cell Anatomy 3

Parts of a Vascular Plant 4

Plant Organs Plant organs include their roots, stems, leaves, and reproductive structures. Each plant organ performs a specialized task in the life of a plant. § Roots, stems, and leaves are all vegetative structures. § Flowers, seeds, and fruits make up reproductive structures. 5

Plant Organ Functions § Roots support the plant and supply it with water and nutrients. § Stems connect the root and leaves. § Leaves capture energy from the sunlight and use it to make food for the plant. § Reproductive structures attract pollinators and produce seeds and fruits. 6

To help prevent soil erosion, which root system would be best? § Fibrous 7

Taproots § Advantages § Penetrates deeper § Obtain water from other levels § Anchor plant § Disadvantages § Difficult to remove or harvest § do not stabilize well 8

PARTS OF PLANT ROOT 9

Fibrous § Advantages § Shallower, better for fertilization & Water § Stabilize in soil better § Disadvantage § Less drought resistant § Tend to get exposed during cultivation 10

Primary Roots § Grow down into the soil and may branch repeatedly into lateral roots § Taproot is a primary root 11

Lateral Roots § Called Secondary roots § grow horizontally away from the primary root § Some grow downward 12

Root Structure Zone of Differentiation Epidermis Cortex Root Hairs Phloem Tubes Zone of Elongation Xylem (water transport) Root Cap Meristem 13

The Epidermis The epidermis is the outermost layer of cells surrounding the root. The cells of the epidermis are responsible for absorbing water and minerals from the soil 14

The Cortex The cortex is a layer of tissue between the epidermis and the vascular tissue. Cortex cells function in the movement of water and in food storage. 15

Root Hairs Root hairs are found along the main root and perform much of the actual work of water and nutrient absorption. Root Hairs Most plants produce root hairs that only live a few days or a few weeks. As a plant grows, new root hairs form. 16

Xylem is the supporting and water conducting tissue of vascular plants. Xylem 17

Phloem is the food conducting tissue of vascular plants, made up of sieve tubes and other cellular material. 18

Meristem The meristem is at the tip of the root and is responsible for manufacturing new cells. This is the area where cell division and growth occur. Meristem 19

Roots § The root is the first plant structure to emerge from a seed during germination. § Roots are mostly found below the soil surface and represent about 50% of a plant’s weight. § The primary functions of roots are to absorb water and nutrients from the soil and to support the plant in an upright position. 20

Root Functions § Roots distribute the food energy produced in the leaves to the rapidly growing areas found at the root tips. § Some plants use their roots as a specialized food storage reserve. § The first root to emerge from a seed is the primary root, or radicle. 21

Roots (taproot) § Plant root systems are classified based on the relative sizes of their primary and secondary roots. § Plants such as dandelions, carrots, turnips, and most trees have a taproot. § In taproot systems, the primary root thickens and becomes the dominant root. 22

Roots (fibrous) § In fibrous root systems, the primary and secondary roots are of similar diameter. § They remain fairly close to the soil surface. § Fibrous root systems help to prevent the erosion of topsoil during heavy rains. § Plants such as onions, grasses, and corn have fibrous root systems. 23

Root Types Tap Root Fibrous Roots 24

Stem Characteristics 25

Stems function as supportive structures. They hold a plant’s leaves up toward the sun so the leaves can capture energy from sunlight. Stems transport water and nutrients from the roots to the leaves, and food energy from the leaves to the roots. 26

Leaf Structure Vein Midrib Expanded Portion of Blade (Lamina) Axillary Bud Node Bladestalk (Petiole) Internode Base of Leaf 27

Leaf Characteristics 28

Midrib & Veins Vein Midrib The midrib is the most prominent, central vein in a leaf. Lateral veins are secondary veins that branch from the midrib. Both midribs and lateral veins contain vascular tissue. 29

Leaf Blade (Lamina) The expanded flat portion of a leaf is the leaf blade, or lamina. 30

Petiole (Bladestalk) The petiole attaches the lamina to the plant stem. Petiole 31

Axillary Bud An axillary bud exists on the stem just above the point where the leaf petiole attaches to the stem. 32

Parts of a Flower Pollen Grains Filament Stigma Style Anther Petal Pollen Tube Ovule Embryo Sac Sepal Microphyle Integuments Ovary Receptacle 33

Complete Flowers Compete flowers have four basic parts: 1. Sepals 2. Petals 3. Stamens 4. Pistil 34

Sepals are leaf-like structures that form an outer ring around the base of a flower. Sepals enclose and protect a flower bud before it opens. Sepals The complete ring of sepals is called the calyx. 35

Petals are often the bright and colored part of a flower. Petal colors and scents attract specific pollinators. Petals 36

Stamens Anther Filament The stamen contains both the filament and the anther. The filament is a stalklike structure that holds the anther. Stamens are the male reproductive parts of a flower. 37

Pistil Stigma The pistil includes three parts: 1. Stigma 2. Style 3. Ovary Style Ovary 38

Pistil 1. Stigma The stigma is a sticky, flattened surface that projects upwards towards the pollinator. Birds and insects collect nectar from previously visited plants and brush against the sticky surface of the stigma. 39

Pistil 2. Style The style is a supportive structure that holds the stigma in a position to maximize the chances of pollination. Style 40

Pistil 3. Ovary Pollen Tube Ovule Ovary The ovary is an enlarged structure that contains the female sex cells, or ovules. The pollen tube grows through the ovary and into an ovule. 41

Receptacle The enlarged part of the pedicel where it joins the flower is the receptacle. Receptacle 42

Pedicel The pedicel (flower stalk) supports the flower. Pedicel 43

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Acknowledgements Kristi Falco, Graduate Assistant, Instructional Materials Service, researched and developed the information used in this Power. Point Presentation. Christine Stetter, Artist, Instructional Materials Service, developed and illustrated this Power. Point Presentation. . Keith Zamzow, Curriculum Specialist, Instructional Materials Service, edited and reviewed this Power. Point Presentation. Vickie Marriott, Office Software Associate, Instructional Materials Service, edited this Power. Point Presentation. 45

ALL RIGHTS RESERVED Reproduction or redistribution of all, or part, of this presentation without written permission is prohibited. Instructional Materials Service Texas A&M University 2588 TAMUS College Station, Texas 77843 -2588 http: //www-ims. tamu. edu 2006 46