A Surprise Cross Pollination Experiment - Eva Varga

We attended Norway Day in May and enjoyed a variety of activities and cultural presentations.  One of the activities the kids took part in was painting a flower pot and planting a Petunia that they could take home.  Sweetie selected a white Petunia and Buddy, a deep purple (sadly I wasn’t able to get a photo of Buddy’s – he wasn’t happy with his painting and didn’t want me to take a picture).

We brought the flowers home and enjoyed their blooms indoors for a short time.   Frustrated with the dirt spilling on my counter, I suggested the kids put their pots on the front porch.  Sweetie was careful to water hers regularly (Buddy, not so much) and as could be expected, hers bloomed again.  To our surprise, however, her blossoms were no longer white but striped with purple!  “Mom!  Look at my Petunia!  I think bees must have visited both mine and Buddy’s!  Isn’t this cool?”

Cross Pollination

Petunias are flowering plants that belong to the Solanaceae family and are hardy to climates within planting zones 10 to 11. Even though these sun-loving plants grow flowers that contain both the male and female reproductive organs, also known as the stamen and pistil, they won’t self-pollinate. Pollination thereby must occur through insects or wind to transfer pollen from one flower to another.  You can also play the role of the insect and transfer pollen yourself.

When the pollen from one flower is carried to the stigma of another flower they combine their genetic information (RNA) and their seeds should produce a hybrid of the 2 original plants.  The hybrid may not have obvious changes in its appearance because plants carry similar genes. If you want only plants with the same characteristics from year to year then simply save the seeds from your favorite blooms and plant the seeds next year.

hybrid  A cross between two parent plants that are from the same species but don’t look exactly like each other.

This discovery – while unplanned – was a fascinating opportunity for us to further explore the concept of pollination.  While some plants, such as peas, self-pollinate very well; others, such as Petunias, are structured in such a way as to assure cross-pollination.  If your children are full of questions and interested in further exploring cross-pollination, encourage them to set up an experiment to answer their questions.  For example:

Experiment :: What would happen if flowers that usually cross-pollinate were self-pollinated instead?

For this experiment consider using Wisconsin Fast Plants which carry out their entire life cycle in less than a month if grown under constant lighting.  The flowers of Fast Plants have long pistils and short stamens, which makes it difficult, if not impossible, for them to self-pollinate.  Once the plants set seed, wait for the fruits to ripen, then count the seeds in the fruits and examine their quality. Which plants set the most seeds: the cross-pollinated plants or the self-pollinated plants? Was there any difference in the size and development of the seeds? Try germinating the seeds from each set of plants, either on moist soil or moist paper towels. Is there a difference in germination rates?

Submitted to the Outdoor Hour Challenge Blog Carnival at Handbook of Nature Study.