Ch. 31 – Plant Structure & Function Groups of cells that perform a common function are called? Tissue Cells – tissues – organs – systems – organisms Plants are divided into three main groups of tissues 1. Ground tissue 2. Vascular tissue 3. Dermal tissue

Ground tissue Ground tissue contains three main kinds of cells. 1. Parenchyma – most common tissue. Large, thin walled cells for storage mainly, which is helpful in photosynthesis. 2. Sclerenchyma – strong rigid cells. Strengthens and supports the plant. 3. Collenchyma – very flexible cells. Not as rigid as sclerenchyma.

Vascular Tissue Xylem  Water Transport 1. Vessel elements – these are large cells that transport most of the water in a cell. They are dead cells; why are they dead? 2. Tracheids – long, thick walls that are tapered at the ends. Conifers contain mainly tracheids instead of vessel elements.

Phloem  Food Transport 1. Sieve tube members – main cell in food transportation. 2. Companion cells – believed to help the movement of food through the sieve tube members.

Dermal tissue Dermal tissue is outside protective cells 1. Epidermis – outer layer of cells; covered with a cuticle if on land.  Leaf Picture – pg.617 There are 3 regions that stand out: epidermis (dermal , mesophyll (ground tissue), and vascular bundles (vascular tissue). Most photosynthesis takes place in the mesophyll region. This region contains chloroplasts, which we will talk about more specifically.

Primary & Secondary Growth Primary growth occurs in both herbaceous and woody plants. This is growth in length. Secondary growth occurs in woody plants. This is growth in width. The meristem is where cell growth or cell division occurs in plants. 2 types of meristems in plants. 1. Apical Meristem – produces growth in length. Found at the tip of stems and roots. 2. Lateral Meristem – produces growth in width. Found in the stem.

Annual plants live for only a year or less. Most are herbaceous (soft tissues; no woody tissue). Their seeds may grow new plants the next year Examples??? Perennials live for several years; producing seeds each year Dormant in the winter & most have woody tissues. Examples???

Types of Roots 1. Fibrous – most common. Mainly weeds. 2. Tap – largest root. Ex. Carrot 3. Prop – starts above ground, then extends into the soil. Ex. Corn. 4. Adventitious – totally above ground. Ex. Poison ivy Parts of a root: Primary root, lateral roots, root hairs. Root hairs do all of the absorption.

Stems If I drove a nail into a tree 3 feet high into the tree, how high up the tree will the steak be 20 years from then? Why? Parts of a stem 1. Pith – center portion for storage. 2. Dermis 3. Xylem & Phloem  Annual rings

Leaf Structure The leaf is made up of: blade & petiole. Blade is the specific portion of the plant’s photosynthesis process. Other external features of a leaf include the following. 1.Cuticle – waxy protective covering to protect against desiccation. 2. Stomata – are the openings in the cuticle to allow gas exchange (CO2). 3. Guard Cells – make up the stomata; what opens and closes it. Internal Features 1. Mesophyll – contain chloroplasts for photosynthesis. 2. Vascular bundle (veins) – Xylem & Phloem

Compound & Simple Leaves Simple leaves – 1 blade per leaf 1. Parallel venation 2. Pinnate venation 3. Palmate venation Compound leaves – 2 or more blades per leaf. 1. Pinnately compound 2. Palmately compound