Tag Archives: stamen

OS15 Male Pumpkin Flowers

Pumpkins have two kinds of flowers. One flower makes pollen and is called a male flower. Most flowers on a pumpkin plant are male flowers. These have long thin stems called petioles. On the day you want to do this Investigation, go out early in the morning and pick a male flower. It may have insects in it. Use a long grass stem to push them out. Don’t knock the flower about, especially upside down or all the pollen will fall out! Put the flower into a glass of water until you are ready to look it over. It will wilt in just a few hours so let’s start early and find out about a male flower.


Question: What parts are in a male pumpkin flower?


Male Pumpkin Flower

male flower

A male flower has a long, slim petiole. They rise up from leaf nodes, places where the leaf petioles join the pumpkin vine.

Metric ruler


Magnifying glass


Slide and coverslip



Step 1: Open your Science Journal, write “Investigation 15” and the date.

Step 2: Examine the outside of the male flower. Measure how tall it is. Compare it to the diagram of a flower and label your drawing with the parts.

inside male flower

Looking inside a male flower it is easy to see the flower has five petals joined together. The stamens are joined into a single column. Around the base of the column is a trough evidently filled with nectar as insects congregate there. Larger insects would come in contact with the pollen on the stamen column getting it on their bodies so the pollen will be carried off when the insect leaves hopefully stopping by a female flower next.

Step 3: Smell the inside of the flower.

Step 4: Carefully tear or cut off the petals of the flower and lay them out on the table.

Step 5: Examine the petals. Compare the inside and outside surfaces – look, color, feel.

Step 6: Examine the stamen. Measure the stamen. Touch the stamen. Draw and describe what you observe.


Splitting a stamen lengthwise shows the inside is solid. The yellow concentric loops form a thin skin on the outside of the top half of the stamen.

Step 7: Put a drop of water on a slide. Put some of the pollen from the stamen on the water. Put on the coverslip.

Step 8: Examine the pollen with the microscope.

Step 9: Carefully slice the stamen in half lengthwise and examine the inside.

magnified stamen

Magnifying the top of the stamen shows the concentric loops are yellow ridges on a pale base.



male flower petals

The inside of the joined petals is smooth, slick, changing from yellow at the bottom to orange at the top. Large veins run down the center of each petal. The flower wilts quickly after being picked.

outside male flower petals

From the outside the joined petals are more greenish yellow at the base but still orange at their tops. Three veins are obvious on each petal lthough only the middle one is really big on the inside. The petals still feel smooth but don’t have a slick feel.


Explain why you think a pumpkin flower has only one or has many petals joined (fused) together.

If a pumpkin flower has fused petals, how many petals are there? How can you tell?

What advantages would fused petals instead of separate ones give a pumpkin flower? (You might want to look at some flowers on your pumpkin plant in the early morning to get some ideas.)

Each seed in a pumpkin flower needs one grain of pollen to become a seed. Why are there so many more male flowers making pollen than female flowers (These have tiny pumpkins under them.)?

Why do you think the flower makes so much pollen since only one grain or piece is needed for each seed?

male flower stamen

The large stamen has a big base with three feet. It sits in the center of a moat. The five sepals and petals are on the outside edge of this moat. The top of the stamen looks like an unexpanded mushroom but with concentric loops all over it. Pollen is found in the troughs of the loops.

Many flowers have lots of little stamens. A pumpkin flower seems to have only one. Does the pumpkin flower have fused stamens? Explain why you think so.

Different kinds of plants have pollen grains (separate pieces of pollen) with different shapes. Archeologists use fossil pollen to identify the kinds of plants that grew in an area long ago. What special things about a pumpkin pollen grain do you see?