The Garden Goodies 4H club met for their weekly meeting at the Hillsborough County Extension Service office. One of the topics was the plant life cycle. While in the garden, they saw flowers and fruit on the tomato, bean, watermelon, cantaloupe, and zucchini squash plants. Then, back in the kitchen, the students studied seeds.

I read the first part of the book, Oh Say Can You Seed, by Bonnie Worth. The book helped to introduced the idea that there is a plant embryo inside each seed. The students examined garbanzo seeds and kidney bean seeds. They observed that the garbanzo seeds were white, lumpy and hard. The kidney bean seeds were red, smooth and hard. Not all seeds look alike, but they all contain an embryo.

They found that both the garbanzo and kidney bean seeds that had been soaked in water for 2 days were softer (squishier) and larger than the dry seeds. They realized that the seeds were softer and larger because they had soaked in water. The students remembered planting various seeds in the garden and watering the seeds when they were planted. We discussed that all plants need water to grow. They found that the outer seed coat could be easily removed from the seeds that had been soaked in water. The seed coat protects the seed until it starts to germinate, then it loosens as the seed absorbs water and swells.

After they removed the seed coat from the kidney bean seeds, the students could see the two cotyledons (seed leaves) and some students could see the root beginning to grow. The cotyledon provides food for the developing plant embryo inside the seed. I explained that not all plants have two cotyledons. I showed them a cob of corn and explained that corn seeds have only one cotyledon, but corn seeds also have an embryo inside. The purpose of the cotyledon, even if there is only one, is to supply food for the growing plant embryo.

The students gently separated the two cotyledons of the kidney bean. They found the tiny plant embryo at one end of the bean seed cotyledon. The embryo and the cotyledon were both white which made it a difficult to distinguish the embryo from the cotyledon, so I added a few drops of iodine to the cotyledon. The students observed that red iodine turned the cotyledon a blue-black color. Iodine reacts with the starch in the cotyledon, staining the starch dark blue-black.

The contrast between the dark cotyledon and the white embryo made it easier to see the parts of the embryo. Students were able to see the two small leaves of the embryo and the beginning of the first root of the plant.

The Plant Cycle: Plants have roots, stems, leaves and many have flowers that produce fruit with seeds. The students remembered planting and watering the bean seeds. We have watched the bean plants grow, climbing up the net we provided. We have seen the bean flowers and the bean pods growing on the vine. The students could see bean seeds inside the bean pods. The seeds inside the bean pods could be kept until next year to plant new bean plants. That is the plant life cycle. What a continuing miracle of life.