University of Arkansas - AgriScience Project

AGRISCIENCE EXERCISE

PLANT SCIENCE & BIOTECHNOLOGY

Sub-Concept: Stems: Types, Tissues, Structure, Functions

Agricultural Context: Different plant parts are used for agricultural purposes, each of which serves an important function.

Exercise: Specialized Stems

Applied Principle: There are several different types of stems.

Goals:

1. Name the types of specialized stems.
2. Identify and give examples of the types of specialized stems.
3. Propagate plants using specialized stems.

Materials:

• tuber (potato)
• bulbs (onion, lily, tulip, etc.)
• corm (lily)
• runners (begonia, spider plant)
• rhizome (iris)
• pots
• potting soil
• toothpicks
• knife
• clear containers
• shallow dishes
• pebbles
• plant easily propagated by stem cuttings (wandering jew, Swedish ivy, etc.)

References: Trudeau, M. (1994). Plant Morphology and Taxonomy. Ithaca, NY: Cornell I.M.S.

Teacher Preparation Notes:

• Prepare one set of specialized stems for each group you plan to have in each class.
• This activity may be modified to suit you particular classroom situation.

Procedures for Conducting the Activity:

Assign each group to a different type of specialized stem (some groups may have more than one type). Instruct the groups to prepare a short explanation for the rest of the class as to the special characteristics of their assigned stem type. Allow the groups about half of the class period to prepare their explanations, then have each group make its presentation. Groups are free to use any visual aids available to clarify their explanations.

2. Part 2:

Each group will propagate several plants with specialized stems. Each type of stem may be simply placed into pots containing soil; however, it is suggested that some of the potatoes and bulbs be propagated using the following procedures, in order for the students to observe root growth more easily.

3. Potatoes:

a. Cut the potato so that each piece contains at least one eye. (You may wish to explain what an "eye" is at this point.)

b. Plant some eyes in pots containing soil, about 3/4" below the surface.

c. Using toothpicks, suspend the other pieces in a transparent container of water (see Figure 1).

Figure 1

4. Bulbs:

a. Fill a shallow dish to about 2/3 full with pebbles.

b. Label each dish with the type of bulb to be propagated, and the date.

c. Place the flat, thickened portion of the bulb onto the pebbles.

d. Fill the dish with water until the base of the bulb just touches the water.

e. Place the dishes in a cool, sunny location.

-- Always be sure the roots have water!!!! --

5. Have each group set up an observation recording system in a notebook or folder. Allow class time every couple of days for the groups to make and record their observations.

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