IB Biology / IHS
Name: ____________________________ Per. _____
Dissection of a Gladiolus Flower
(adapted from www.bio200.buffalo.edu/GladDis.pdf)
We are going to examine and dissect gladiolus flowers. “Glads” are members of the iris family (Iridaceae)
of flowering plants. The spectacular flower spikes are the products of centuries of hybridization and
selection for showy flowers. Each flower is, botanically speaking, complete, meaning it has all the
requisite parts of a flower: male and female organs, plus petals and sepals. Gladiolus is from the Latin
word gladius, meaning “little sword,” and refers to the plants’ narrow, sturdy, sword-shaped leaves.
Materials per table: Spike with several gladiolus flowers, dissecting tools (scissors, forceps, pointers, scalpels), two
magnifying glasses, two dissecting microscopes, two compound microscopes, slides and coverslips, and a water bottle.
1. Start by coloring the flower in Figure 1 below so that it resembles your flower.
2. Carefully remove one flower from the stem by cutting along the angle of attachment (see Fig. 1).
3. There are two green “leaves” (actually stem parts) called bracts at the base of the flower.
Carefully peel them all the way off, being careful not to damage the ovary.
4. Set the cut flower down so you can examine it. Try to identify its key parts using Fig. 1 below.
Note that the outermost “colored leaves,” 4, 5 and 6, are sepals, while the innermost “colored
leaves,” 1, 2 and 3, are petals. Because they look similar in a gladiolus, we will call all of them
tepals. (In most flowers, sepals are small and green.)
Protective leaflike bract
Figure 1. Floral organs of the gladiolus
5. Now, bend the sepals backward until they crack. Cut them off at a point of break with scissors.
Remove the petals in the same way.
6. Examine the surfaces of both petals and sepals (tepals). Note how clearly the veins show up,
indicating that the tepals are really modified leaves with color pigment for attracting pollinators.
In the wild, gladioli are pollinated by certain bees, moths, and birds.
7. The specimen now looks like a cup with
protruding stalks. See Fig. 2. With a scalpel,
Fig. 2
make two cuts from points A and B down to
the top of the ovary at the base of the tepals.
Fold down and cut off this section of tepals.
Remove remaining parts of tepals similarly.
Try not to damage the attached stamens.
8. Examine the exposed area. Note deeper
streaks of color at the base of the petals. These act as color road maps to guide insects or birds
seeking nectar.
9. Carefully remove the stamens, or male organs. See Fig.3. How many are
there? ____ stamens.
Fig. 3
10. Hold one stamen at its lower end and strike its anther sharply against a glass
slide. Add a drop of water and a cover slip, and examine the slide with a
microscope under low and high power to get a better view of the pollen that
came out of the anther. Draw the pollen on 400X of the compound
microscope. Pollen contains sperm cells.
Fig. 4
11. Now that the stamens have been removed, we will dissect the
pistil, the female organ of the flower. Study Fig. 4 to the left.
Examine the external appearance of the ovary. See the longitudinal
lines or sutures? They provide evidence that the gladiolus pistil is
really 3 sections, or carpels, that have fused together.
12. Hold the ovary in place with forceps, as shown.
You can make two shallow cuts down two of the
longitudinal lines, angling your cuts so as to cut out a
section of the ovary like cutting a slice of cake (Fig.
5). Or, you can make a cross-section of the ovary. Observe the slice or the
cross section on either 20X or 40X with the stereomicroscope. The numerous
small white structures are ovules. An ovule contains an egg cell. Make an
informative drawing.
Fig. 5
Fertilized, mature ovules develop into seeds within the ovary. The ovary of the flower has an
additional role. It develops, matures, and ripens into a fruit (often along with other connected parts
of the flower). So, botanically speaking, any plant part with seeds is a fruit – tomatoes, eggplants,
pumpkins, cucumbers, etc.
What is the difference between pollination and fertilization? (Hint: review Figure 1 again!) ___________________
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Be sure to attach your page with two microscope drawings to this handout before turning it in!