Roots, Stems, and Leaves

Specialized Tissues In Plants A. Seed Plant Structure 1. Roots 2. Stems 3. Leaves B. Plant Tissue Systems C. Dermal Tissue D. Vascular Tissue 1. Xylem 2. Phloem E. Ground Tissue F. Plant Growth and Meristematic Tissue

Seed Plant Structure The cells of seed plants are organized into tissues and organs. The three main plant organs are roots, stems, and leaves. Roots absorb water and dissolve nutrients and anchor plants in the ground. Stems support the plant body and transport materials throughout the plant. Leaves are the main organs of photosynthesis. They also function in gas exchange.

Root, Stem, and Leaf Tissues Dermal tissue Vascular tissue Ground tissue

Plant Tissue Systems Within the roots, stems, and leaves are specialized tissue systems. The three main tissue systems: Dermal tissue is like the skin of a plant. It protects the plant and prevents water loss. Vascular tissue consists of xylem (move water throughout the plant) and phloem (moves sugars and other materials throughout the plant). Ground tissue is made up of all of the cells that lie between dermal and vascular tissues. (made up of 3 kinds of cells) Parenchyma cells: function in photosynthesis and storage Collenchyma cells: help support larger plants Sclerenchyma cells: make ground tissue tough and strong

Plant Tissue Systems Cont. A fourth kind of tissue, meristematic tissue, is responsible for plant growth. Meristematic tissue is the only plant tissue that produces new cells by mitosis. The tips of stems and roots are made of meristematic tissue.

Concept Map Plant Tissues include Dermal tissue Meristematic tissue Vascular tissue Ground tissue includes includes includes Epidermal cells Xylem Phloem Parenchyma cells Collenchyma cells Schlerenchyma cells includes includes Tracheids Vessel elements Sieve tube elements Companion cells

Roots The two main types of roots are taproots and fibrous roots. Taproots: the primary root grows long and thick, while the secondary roots stay small. Fibrous roots: secondary roots that grow and branch out Roots have two main functions To anchor a plant in the ground To absorb water and dissolved nutrients form the soil

Taproots and Fibrous Roots Taproots (Carrots) Fibrous Roots (Grasses)

Cross Section of Plant Root (magnification: 40x) The Structure of a Root Epidermis Root hairs Phloem Xylem Apical meristem Root cap Zone of maturation Zone of elongation Endodermis Ground tissue (cortex) Vascular Cylinder Ground tissue (cortex) Epidermis Endodermis Vascular cylinder Cross Section of Plant Root (magnification: 40x)

Stems Stems have three important functions To produce leaves, branches, and flowers To hold leaves up to the sunlight To carry water and nutrients between the roots and leaves

Plant stems grow in two ways Comparing Primary and Secondary Growth of Stems Characteristics Where It Occurs Effect on Plant How It Is Produced Primary Growth Secondary Growth At ends of plants Increases plant length By cell division in the apical meristem In stem Increases stem width By cell division in meristems other than the apical meristem

Leaves The structure of a leaf is optimized for absorbing light and carrying out photosynthesis. To collect sunlight, most leaves have thin, flattened sections called blades. Plants can lose water out of their leaves as they exchange gases with the air (transpiration). To prevent major water loss plants allow air in and out of their waterproof covering only through small openings called stomata. Plants keep their stomata open just enough to allow photosynthesis to take place but not so much that they lose an excessive amount of water.

Transpiration A B Evaporation of water molecules out of leaves. Pull of water molecules upward from the roots.

Blades On Leaves

The Internal Structure of a Leaf Cuticle Veins Epidermis Palisade mesophyll Xylem Vein Phloem Spongy mesophyll Epidermis Stoma Guard cells

Transport in Plants Forces of Attraction Molecules of a similar substance are attracted to one another by a force called cohesion. Molecules of different substances are attracted to one another by a force called adhesion.

Transport In Plants Phloem Xylem Sugar molecules Source cell Movement of water Movement of sugar Sink cell