Chapter #42 – Plant Anatomy & Nutrient Transport 42.1 - How Are Plant Bodies Organized; How Do They Grow? p. 860 42.2 - The Tissues and Cell Types of Plants? p. 862 42.3 - The Structures, Functions of Leaves, Roots, & Stems? p. 865 42.4 - How Do Plants Acquire Mineral Nutrients? p. 873 42.5 - How Do Plants Move Water Upward from Roots to Leaves? p. 876

Plant Anatomy Systems and Tissues How Are Plant Bodies Organized, and How Do They Grow? Flowering Plants Consist of a Root System and a Shoot System. As Plants Grow, Meristem Cells Give Rise to Differentiated Cells.

Herbaceous Plants Soft-bodied plants with flexible stems. Most are annual (live only one year). Exhibit primary growth. e.g. lettuce, beans, grasses

Woody Plants Plants with hard, thickened, woody stems Most are perennial (live many years) Exhibit primary and secondary growth e.g. trees, bushes

Leaves

Types of Leaves Simple leaves have a single blade on one petiole. Compound leaves have multiple leaflets on one petiole.

Leaf Parts Two major parts to the leaf: Blade Petiole

Leaf Microanatomy Epidermis and cuticle slow evaporation. Guard cells regulate gas exchange. Mesophyll carries out photosynthesis Veins bring water, move sugars.

Photosynthesis The purpose of photosynthesis is to produce organic (carbon-based) molecules (such as sugars). The plants use these molecules for two purposes: As an energy source As building material

Stop and think: On a piece of paper, list plant leaves or products of plant leaves that you have used in the past few days. What qualities of the leaves made them useful?

Roots

Types of Root Systems Taproot systems are found in dicots, and consist of a main root with lateral branches. Fibrous root systems lose the primary root, which is replaced by many smaller roots.

Root Anatomy Parts of a Root: Root cap Root meristem Zone of elongation Zone of maturation

Root Anatomy: Epidermis Root epidermis lacks a cuticle, and is porous. Usually has many root hairs. Water enters through membranes of epidermal cells or through spaces between cells.

Root Anatomy: Cortex The cortex layer is made up of parenchyma cells. Sugars are linked to make starch for food storage. Endodermis separates the cortex from the vascular cylinder.

Root Anatomy: Vascular Cylinder Casparian strip around endodermis cells controls water movement. Pericycle: layer of parenchyma cells, inside of endodermis, from which branch roots can arise.

Root Anatomy: Vascular Cylinder Vascular Cylinder contains: Phloem for moving sugars. Xylem for moving water and dissolved minerals.

Stop and think: On your own paper, list any roots that you have used in the past few days. What qualities of the roots made them useful?

Stems

Stems: Epidermis In herbaceous plants and young woody plants, the stem is covered with epidermis. Epidermis secretes cuticle, has stomata, and may be photosynthetic.

Stems: Cortex and Pith Cortex layer contains parenchyma cells and vascular bundles. Pith makes up the center of the stem, and is absent in hollow stems.

Stems: Vascular Tissue Vascular bundles are in the cortex. While primary xylem and phloem are made by the apical meristem, secondary xylem and phloem come from the vascular cambium, another meristem tissue.

Trunk: Primary Growth Primary Growth is primarily vertical. This kind of growth gives the plant its height.

Trunk: Secondary Growth Secondary growth is seen in woody plants. This kind of growth produces stronger, thicker stems from the vascular cambium and cork cambium. Horizontal Growth

Wood and Bark Xylem makes up the wood of trees and shrubs. Live phloem cells form the green bark. Dead cork cells make up the bark.

Annual Rings Trees in temperate zones grow at different rates in different seasons, causing annual rings to form. In some parts of the tropics, if seasons vary little, tree rings are indistinct.

Stop and think: On your own paper, list any stems or products of stems you have used in the last few days. What qualities of these stems made them useful?

Meristem Cells Meristem cells are undifferentiated cells; able to divide as long as the plant lives. Apical meristems are located at tips of roots and shoots.

Meristem Cells Differentiated cells are mature cells specialized for a specific function. Derived from meristem cells that lose the ability to divide. Usually do not divide. Example: vessel elements and tracheids of xylem.

Meristem Cells Meristems allow plants to grow throughout their lives. Primary growth occurs by division of apical meristem cells and differentiation of their daughter cells. Responsible for growth in length of roots and shoots of all plants.

Meristem Cells Secondary growth occurs by division of lateral meristem cells and differentiation of their daughter cells. Responsible for an increase in diameter of roots and shoots of most conifers and dicots. Lateral meristems or cambia (singular, cambium) run parallel to the long axis of roots and shoots.