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Section 23–3 Stems
Class __________________
Date ______________
(pages 589–594)
TEKS FOCUS: 5A Specialized cells in stems; 13A Structural adaptations of plants to environment
This section explains the two main functions of stems and how monocot and dicot
stems differ. It also describes primary growth and secondary growth in stems.
Stem Structure and Function
(page 589)
1. What are the two important functions of stems?
a. They hold leaves up to the sunlight.
b. They transport substances between roots and leaves.
2. What three tissue systems compose a stem? Dermal, vascular, and ground tissue
Match the stem structure with its description.
Structure
Description
c
3. Node
a
4. Internode
b
5. Bud
a. A region between nodes
b. Contains undeveloped tissue that can produce new stems
and leaves
c. Where leaves are attached
Monocot and Dicot Stems
(page 590)
6. How does the arrangement of tissues in a stem differ among seed plants?
In monocots, vascular bundles are scattered throughout the stem. In dicots and most
gymnosperms, vascular bundles are arranged in a cylinder.
7. In a monocot stem, what does each vascular bundle contain? Each contains xylem and
phloem tissue.
8. What is the arrangement of vascular tissue in a monocot stem? Vascular bundles are
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scattered throughout the stem.
9. What is the arrangement of vascular tissue in a dicot stem? Vascular bundles are
arranged in an organized, ringlike pattern.
10. The parenchyma cells inside the ring of vascular tissue in a dicot stem are known
as
pith
.
11. What do the parenchyma cells outside the ring of vascular tissue form in a dicot stem?
They form the cortex of the stem.
Primary Growth of Stems
(page 590)
12. What is primary growth in a plant? Primary growth is the increase in plant length caused by
the production of new cells at the tips of roots and shoots.
13. Primary growth of stems is produced by cell division in the
Guided Reading and Study Workbook/Chapter 23
apical meristem
.
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14. Is the following sentence true or false? Only dicot plants undergo primary growth.
false
Secondary Growth of Stems
(pages 591–594)
15. The pattern of growth in which stems increase in width is called
secondary growth
.
16. In conifers and dicots, where does secondary growth take place? It takes place in lateral
meristematic tissues called the vascular cambium and cork cambium.
17. What type of lateral meristematic tissue produces vascular tissues and increases the
thickness of stems over time? Vascular cambium
18. What does cork cambium produce? It produces the outer covering of stems.
19. Circle the letter of each sentence that is true about the formation of vascular cambium.
a. Vascular cambium forms between the xylem and phloem of individual vascular
bundles.
b. Divisions of vascular cambium give rise to new layers of xylem and phloem.
c. Once secondary growth begins, vascular cambium appears as a thin layer.
d. The production of new layers of xylem and phloem causes the stem to shrink when
secondary growth begins.
20. Is the following sentence true or false? Most of what we call “wood” is actually
layers of phloem.
false
21. What is heartwood? It is the darker wood near the center of the stem that no longer conducts
water.
22. The wood that is active in fluid transport and therefore lighter in color is
called
sapwood
.
23. The alternation of dark and light wood produces what we commonly
tree rings
.
24. How can you estimate the age of a tree? You can estimate a tree’s age by counting the rings
in a cross section of the tree.
25. On most trees, what does bark include? Bark includes all tissues outside the vascular
cambium, including phloem, the cork cambium, and cork.
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26. Circle the letter of each sentence that is true about cork.
a. Cork cells usually contain fats, oils, or waxes.
b. Cork cells cause the loss of water from a stem.
c. The outermost cork cells are usually dead.
d. Cork cambium produces a thick, protective layer of cork.
27. Label the parts of the illustration of wood.
Wood
Bark
Cork
Cork
cambium
Heartwood
Phloem
Vascular cambium
Sapwood
28. What are four kinds of modified stems that store food?
a. Tuber
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b. Bulb
c. Rhizome
d. Corm
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