Apical Meristems Because the tip of a stem or root is known as its apex, meristems in these rapidly growing regions are called apical meristems. Unspecialized cells produced in apical meristems divide rapidly as stems and roots increase in length. Figure 23–4 shows examples of stem and root apical meristems.

At first, the new cells that are pushed out of meristems look very much alike: They are unspecialized and have thin cell walls. Gradually, they develop into mature cells with specialized structures and functions. This process is called differentiation. As the cells differentiate, they produce each of the tissue systems of the plant, including dermal, vascular, and ground tissue.

Meristems and Flower Development The highly specialized cells found in cones and flowers (which are the reproductive organs of seed plants), are also produced in meristems. Flower or cone development begins when the pattern of gene expression changes in a stem's apical meristem. These changes transform the apical meristem of a flowering plant into a floral meristem. Floral meristems produce the tissues of flowers, which include the plant's reproductive organs as well as the colorful petals that surround them.

BUILD Vocabulary

RELATED WORD FORMS Apex and apical are related word forms. Apex is a noun meaning the narrowed or pointed end, or tip, and apical is an adjective describing something related to or located at the apex.

A plant with its root's and stem's tip magnification in two inset diagrams showing a root apical meristem and a stem apical meristem.

FIGURE 23–4 Apical Meristems Apical meristems are found in the growing tips of stems and roots. Within these meristems, unspecialized cells are produced by mitosis.

23.1 Assessment

Review Key Concepts

    1. Review What are the three main organs of seed plants?

    2. Interpret Diagrams Review Figure 23–1. How are the three main organs of seed plants similar in structure?

    1. Review What are the three main tissue systems of plants?

    2. Compare and Contrast How do the main functions of a plant's tissue systems differ?

    1. Review What is the function of meristems?

    2. Form a Hypothesis How might the presence of meristems explain the ability of plants to regenerate from cuttings?

Apply the Big idea

Structure and Function

  1. You probably have some knowledge of the human circulatory system. Based on this knowledge, write a paragraph comparing and contrasting the structure and function of the vascular system of a plant to the human circulatory system. Hint: Show how the systems are alike and different.

End ofPage 668

Table of Contents

Miller & Levine Biology
About the Authors
Changing the World of Biology Education
Contents
Diversity of Life: A Visual Guide DOL•1–DOL•64
Labs and Activities
Features
UNIT 1 The Nature of Life
1 The Science of Biology
2 The Chemistry of Life
Unit Project
UNIT 2 Ecology
3 The Biosphere
4 Ecosystems and Communities
5 Populations
6 Humans in the Biosphere
Unit Project
UNIT 3 Cells
7 Cell Structure and Function
8 Photosynthesis
9 Cellular Respiration and Fermentation
10 Cell Growth and Division
Unit Project
UNIT 4 Genetics
11 Introduction to Genetics
12 DNA
13 RNA and Protein Synthesis
14 Human Heredity
15 Genetic Engineering
Unit Project
UNIT 5 Evolution
16 Darwin's Theory of Evolution
17 Evolution of Populations
18 Classification
19 History of Life
Unit Project
UNIT 6 From Microorganisms to Plants
20 Viruses and Prokaryotes
21 Protists and Fungi
22 Introduction to Plants
23 Plant Structure and Function
24 Plant Reproduction and Response
Unit Project
UNIT 7 Animals
25 Introduction to Animals
26 Animal Evolution and Diversity
27 Animal Systems I
28 Animal Systems II
29 Animal Behavior
Unit Project
UNIT 8 The Human Body
30 Digestive and Excretory Systems
31 Nervous System
32 Skeletal, Muscular, and Integumentary Systems
33 Circulatory and Respiratory Systems
34 Endocrine and Reproductive Systems
35 Immune System and Disease
Unit Project
A Visual Guide to The Diversity of Life
HOW TO USE THIS GUIDE
THE TREE OF LIFE
Bacteria
Protists
Fungi
Plants
Animals
Appendices
Appendix A Science Skills
Appendix B Lab Skills
Appendix C Technology & Design
Appendix D Math Skills
Appendix E Periodic Table
Glossary
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q, R
S
T
U
V
W
X, Y, Z
Index
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
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W
X
Y
Z
Credits
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