Lecture 5: Chapter 25

Alberts, B

ray, H

opkins, Johnson

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Professor: Dr. BarjisRoom: P313Phone: (718)2605285Email: ibarjis@citytech.cuny.edu

General BiologySylvia S M

ader

Lecture 5: Chapter 25

Structure and Organization of Flowering Plants

Outline

• Plant Organs– Roots – Stems– Leaves

• Monocots vs. Eudicots

• Epidermal Tissue• Vascular Tissue

• Roots– Organization– Diversity

• Stems– Organization– Diversity

• Leaves– Organization– Diversity

Plant Organs

• Roots function– Anchors plant in soil.– Absorbs water and minerals.– Produces hormones that stimulate growth

and coordinate the plant size with their root size

• The root system contains primary root, lateral root and root hair.

Organization of Plant Body

Stems

• Shoot system of a plant is the aboveground portion of the plant.

• The shoot system of the plant is composed of the stem, the branches and the leaves.– Stem support leaves in such a way that

each leaf is exposed to as much sunlight as possible.

– In addition to supporting the leaves, a stem has vascular tissue (Xylem and Phloem)

Organization of Plant Body

Leaves

• Leaves are the major part of the plant that carries on photosynthesis.

• The process of Photosynthesis require:– Water– Carbon dioxide– Sunlight

Plant Tissues

• Epidermal Tissues– Is the outer protective covering of the

plant

Ground Tissue

• Ground tissue makes up the majority of the interior of the plant

Vascular Tissue

• xylem and phloem

Xylem Structure

Root Diversity

Stem Diversity

Leaf

• The epidermis is covered by a waxy layer of cuticle that reduces water loss.

• Gas exchange occurs through tiny openings in the leaf surface called stomates.

• Regulation of gas exchange through the leaf is the responsibility of the guard cells.

Organization of Leaves