Plant Notes Roots, Stems, and Leaves qwet Chapter 23

Roots, Stems, and Leaves Three of the principal organs of seed plants are roots, stems. and leaves.Three of the principal organs of seed plants are roots, stems. and leaves. Function in: 1.Transport 2.Protection 3.Coordination of plant activities

Plant Tissue Systems Plants consist of three main tissue systems: 1.Dermal tissue 2.Vascular tissue 3.Ground tissue

Dermal Tissue The “skin” of a plantThe “skin” of a plant Contains a waxy cuticle to prevent water lossContains a waxy cuticle to prevent water loss

Vascular Tissue Plants “bloodstream”Plants “bloodstream” Transports water and nutrients throughout the plant.Transports water and nutrients throughout the plant. Made of Xylem and PhloemMade of Xylem and Phloem Phloem Xylem Phloem

Xylem Water conducting tissueWater conducting tissue

Phloem Food conducting tissue.Food conducting tissue.

Roots Two main types: 1.Taproots – found mainly in dicots 2.Fibrous roots found mainly in monocots

Root Structure and Growth The root’s surface is covered with cellular projections called root hairs. Root hairs provide a large surface area through which water can enter the plant.The root’s surface is covered with cellular projections called root hairs. Root hairs provide a large surface area through which water can enter the plant. Root hairs

Root Function Anchor a plantAnchor a plant Absorb waterAbsorb water Absorb dissolved nutrientsAbsorb dissolved nutrients

Stems- Functions Produce leaves, branches and flowersProduce leaves, branches and flowers Hold leaves up in the sunlightHold leaves up in the sunlight Transport various substances between roots and leavesTransport various substances between roots and leaves

Copyright Pearson Prentice Hall Monocot and Dicot Stems Monocot and Dicot StemsMonocot and Dicot Stems –The arrangement of tissues in a stem differs among seed plants. –How do monocot and dicot stems differ?

Copyright Pearson Prentice Hall Monocot and Dicot Stems Monocot Stems Vascular bundles are scattered throughout the ground tissue. Monocot Vascular bundles Epidermis Ground tissue

Copyright Pearson Prentice Hall Monocot and Dicot Stems –Dicot Stems Dicot stems have vascular bundles arranged in a ring- like pattern. Dicot Cortex Pith Vascular bundles Epidermis

Leaves Leaves The structure of a leaf is optimized for absorbing light and carrying out photosynthesis.

Leaf Functions The air spaces connect with the exterior through stomata.The air spaces connect with the exterior through stomata. Stomata are porelike openings in the underside of the leaf that allow carbon dioxide and oxygen to diffuse into and out of the leaf.Stomata are porelike openings in the underside of the leaf that allow carbon dioxide and oxygen to diffuse into and out of the leaf. Stoma

Copyright Pearson Prentice Hall Leaf Functions Each stoma consists of two guard cells.Each stoma consists of two guard cells. Guard cells are specialized cells that control the opening and closing of stomata by responding to changes in water pressure.Guard cells are specialized cells that control the opening and closing of stomata by responding to changes in water pressure. Guard cells

Copyright Pearson Prentice Hall Leaf Functions When water pressure within guard cells is high, the stoma open.When water pressure within guard cells is high, the stoma open.

Copyright Pearson Prentice Hall Leaf Functions When water pressure within guard cells decreases, the stoma closes.When water pressure within guard cells decreases, the stoma closes.

Copyright Pearson Prentice Hall Leaf Functions Plants regulate the opening and closing of their stomata to balance water loss with rates of photosynthesis.Plants regulate the opening and closing of their stomata to balance water loss with rates of photosynthesis. Stomata are open in daytime, when photosynthesis is active, and closed at night, to prevent water loss.Stomata are open in daytime, when photosynthesis is active, and closed at night, to prevent water loss. In hot, dry conditions stomata may close even in bright sunlight, to conserve water.In hot, dry conditions stomata may close even in bright sunlight, to conserve water.