1. STC Plant Growth and Development Lesson 11: Pollinating Flowers Kennewick School District

2. Overview For five consecutive school days (Day 12 through Day 18), students use their bee sticks to cross-pollinate their plants. Through discussions and readings, they will come to appreciate the interdependent relationship of the bee and the Brassica. This is a hidden slide for teacher information. STC Plant Growth and Development Lesson 11: Pollinating Flowers

3. Lesson Objectives  Students use the bee sticks to cross-pollinate their plants.  Students read more about the interdependence of bees and flowers. This is a hidden slide for teacher information. STC Plant Growth and Development Lesson 11: Pollinating Flowers

4. Background There are many examples of symbiotic relationships in nature, where each partner is dependent on the other, For example, there is the mutually beneficial association of cattle and the cattle egret. The cattle are useful to the birds because they provide food—ticks that have a parasitic relationship with the cattle. The birds are useful to cattle because they free cattle from these ticks., Between bees and flowering plants, they symbiotic relationship is miraculously complex. This is a hidden slide for teacher information. STC Plant Growth and Development Lesson 11: Pollinating Flowers

5. Background To us, the flower is a thing of beauty, delighting our senses with color and perfume. But in nature, the flower is actually a specialized reproductive part whose sole purpose is to manufacture seeds. In the Brassica flower, the male parts (the six pollen-producing anthers) encircle the female part (the ovule-laden pistil). For an ovule to become a seed, it must be fertilized by a pollen grain from the same kind of flower. For Wisconsin Fast Plants, the pollen can not come from the same flower or from a flower on the same plant. In fact, each plant’s stigma not only can chemically recognize its own pollen, but has a way to physically prevent its own pollen from reaching its ovule. Cross-pollination ensures that the plant genes are well crossed. This is a hidden slide for teacher information. STC Plant Growth and Development Lesson 11: Pollinating Flowers

6. Background The Brassica’s yellow pollen grains are so heavy and sticky that they can not be picked up by wind. Somehow this immobile plant must get some pollen from another plant in order to produce fertile seeds. It also must have a way to contribute pollen to other plants. Happily, a remarkably well adapted pollen vector has evolved: the worker bee. From the bee’s perspective, the flower represents food—nectar and pollen. Attracted to the flower by its bright yellow color, the worker bee lands on a petal and thrusts her head deeply into the flower to reach the sweet nectar, sucking it up through a straw-like tongue. As the bee does this, her body also brushes against the stigma, which is sticky. The sticky stigma picks up other flowers’ pollen trapped in the bees hairs. Unwittingly, while foraging for food the bee has also cross-pollinated the plants. Figure 11-1 on pg. 70 shows a bee pollinating a Brassica plant. This is a hidden slide for teacher information. STC Plant Growth and Development Lesson 11: Pollinating Flowers

7. Background Before the bee flies back to the hive, she uses brushes on her midleg to collect excess pollen from her head and thorax. Then she places the pollen in specialized pollen baskets, located on the hind leg, for transport back to the hive. There it is consumed by the bees for its protein, fats, vitamins, and minerals. The nectar gathered from the plant is stored by the bee in her crop, a nondigesting honey stomach. When the crop is full, the bee regurgitates the nectar in it into a storage cell in the hive. The nectar is the bee’s source of carbohydrates. Through evaporation and the action of enzymes, the nectar becomes honey. Bee and flower: each has benefited from the relationship. Each has provided the other with vital necessities. Each depends on the other to survive. This is a hidden slide for teacher information. STC Plant Growth and Development Lesson 11: Pollinating Flowers

8. Materials list For each student:  Student notebook  1 bee stick  Plants with open flowers For every two students:  1 hand lens STC Plant Growth and Development Lesson 11: Pollinating Flowers

9. Pick up your plants, bee sticks, and hand lens from the distribution station. STC Plant Growth and Development Lesson 11: Pollinating Flowers

10. Use the bee to transfer pollen from the blossom on one plant to the blossom on another plant. Pollinate every blossom that is open by rotating the bee gently. STC Plant Growth and Development Lesson 11: Pollinating Flowers

11. Remember to cross-pollinate! Brassica flowers must be cross-pollinated. That means the pollen from one plant can not pollinate any of the flowers on that same plant. Pollen must be carried from the flower of one plant to the flower of another plant. STC Plant Growth and Development Lesson 11: Pollinating Flowers

12. Use the hand lens to look for:  pollen on different parts of the plant  pollen trapped in the bee’s hairs STC Plant Growth and Development Lesson 11: Pollinating Flowers

13. Clean up and put all supplies where they belong. STC Plant Growth and Development Lesson 11: Pollinating Flowers

14. Figure 11-1 Bee pollinating a Brassica flower STC Plant Growth and Development Lesson 11: Pollinating Flowers

15. What does the bee get from the flower? Figure 11-1 In real life, what attracts the bee to the flower? How does the bee reach the sweet nectar in the bottom of the flower? What else do you notice about the bee? STC Plant Growth and Development Lesson 11: Pollinating Flowers

16. What does the flower get from the bee? Figure 11-1 Look for the female parts of the flower—the pistil with the sticky stigma. Look for the male parts of the flower—the anthers on stalks called filaments. The anthers hold the pollen. How do you think the male part (pollen) of one plant can get to the female part (stigma) of another plant? STC Plant Growth and Development Lesson 11: Pollinating Flowers

17. Reading Selection: The Bee and the Brassica: Interdependence STC Plant Growth and Development Lesson 11: Pollinating Flowers

18. Reading Selection: The Bee and the Brassica: Interdependence STC Plant Growth and Development Lesson 11: Pollinating Flowers

19. Update your Table of Contents STC Plant Growth and Development Lesson 11: Pollinating Flowers

20. cross-pollination The process by which pollen is carried from the male part of a flower to the female part of another flower. Add this vocabulary word and its meaning to your glossary. STC Plant Growth and Development Lesson 11: Pollinating Flowers