Objective

 Students will learn that the air contains numerous microscopic particles include many types of pollen and spores.

 Method

 The class will expose microscope slides for 24 hours in an outdoor location. A drop of pollen stain will be added and the slide covered with a coverslip. The slide is then ready to be examined using a microscope. The pollen grains will stain bright pinkish-red while fungal spores do not stain. Many spores are yellow, golden, or brown while others are colorless. Students should be able to see many types of pollen and spores and also see that there are more spores in the air than pollen.

 Background

I – Pollen

Pollen is part of the reproductive cycle in flowering plants and is produced by the male parts of the flower. The female parts of the flower produce ovules. In order for seeds to be produced, the pollen must be transferred from the male part of the flower to the female part of the flower. Pollen is transferred by wind or carried by insects. Insect-pollinated flowers usually have large, showy, and brightly-colored petals, which attract insects. In wind-pollinated plants the flowers are very small and inconspicuous. They produced enormous quantities of lightweight pollen that is readily dispersed by the wind.

During springtime the atmosphere contains many types of tree pollen. In Tulsa this is our most abundant pollen season. This project can also be planned for the start of the school year since late summer and early fall is the time when weed pollen is abundant.

 II – Spores

Fungal spores are the reproductive structures of fungi including molds and mushrooms. The spores are always microscopic and can have many different sizes and shapes. The spores of most fungi are dispersed by wind and often occur in the atmosphere at high concentrations. They are more abundant than pollen in the atmosphere. Fungal spores are present from early spring through late fall (and also occur in winter but at lower levels).

The major purpose of this activity is for students to increase their awareness of what is actually in the air. Although the air may look clear there may be many microscopic particles present in the air including large quantities of airborne pollen and spores. These particles may be important in the reproduction of flowers or fungi.

Materials

1. Glass microscope slides
2. Vaseline
3. Plastic Coverslips
4. Pollen stain
5. Microscope

 Procedures:

1.  Before presenting this exercise, have students review the parts of a flower and how pollen is involved in the formation of seeds. Also explain how spores are important for the reproduction of fungi (just like seeds are for plants).
2. Apply a very thin coat of Vaseline over an area that is about one square inch in the middle of a microscope slide. Only coat one side
3. Place the slide outdoors in a location where it will not be disturbed. A windowsill will work nicely. Make sure the coated surface is facing upward. Leave the slide undisturbed for 24 hours.
4. Apply one drop of the pollen stain and then add the coverslip.
5. View with a microscope. Both pollen and spores are very small and can be seen best at a magnification of about 400X. This is usually available on most school microscopes.
6. It should be possible to see several types of pollen grains. Check the pollen page on web site for this workshop to see many types of tree pollen found in the springtime.