Helps students understand plant reproduction, plant anatomy, hybrids, and seed formation
Type of Activity:
- Hands-on Activity
- Inquiry lab
- Authentic assessment
- Group/cooperative learning
- Life Science
- Advanced/AP Biology
- Environmental Studies
I give each group of two students a mature amaryllis bulb. They are given pots and soil with minimal planting instructions. Their overall task is to raise the next generation of amaryllis, which appeals to them as they are the next generation. I require that they keep a log noting timing and amounts of water and fertilizer, growth of bloom stem and leaves in cm, and any other information that they choose, such as sun and temperature conditions.
When the flowers open, they are to transfer the pollen from the male parts to the female part of the flower by hand. Some of my classes predict whether self-pollination or cross-pollination with another plant with the same or different colored flowers will produce the most seeds. They must improvise to find ways to mark flowers and prevent further pollination. The seeds mature in the ripening ovary over the next few weeks. When the ovary splits it is time to count the seeds and plant them. Number of seeds and germination rates are recorded. When the seedlings appear, I tell them that they have passed "plant."
Students are allowed to take their seedlings home if they wish. I take the mature bulbs and seedlings home and plant them in my garden for the summer and bring them in after the first frost to dry for January planting. This keeps the cost down. It takes three years to produce a bulb that will flower.
Students are required to:
- Plant bulbs, measure the growth of bloom stem and leaves, and record this and any other pertinent data in a log
- Predict the success, in terms of number of offspring, of self-pollination and cross-pollination with a plant with flowers of the same or a different color, and conduct the appropriate crosses
- They must also figure out how to mark flowers and to prevent unwanted crosses
- Count and plant the seeds when they mature
No preparation time is required. Planting the bulbs and counting and planting seeds takes one class period at most. Daily log entries and pollination can be done at the beginning or end of a class period. The bulbs take about four weeks to flower, seeds form in two or three weeks after pollination, and seedlings appear in three or four weeks after planting.
This activity allows students to follow plant reproduction from planting Amaryllis bulbs through pollination of the flowers, production of seeds, planting of those seeds, and finally the growth of a new generation of plants. Students hypothesize about the results of different crosses, keep a log of observation and data, and summarize the results.
- One Amaryllis per two students
- Potting soil
Students plant their bulb and begin a log where they record the length of both the bloom stem and one leaf in cm daily as well as timing and amount of water. They also record other observations of their own choosing, like sun and temperature conditions or the addition of fertilizer. When the flowers open, they transfer pollen from the male parts to the female part of the flower by hand. They need to predict whether self-pollination or cross-pollination with a plant with the same or different colored flowers will produce the most seeds. They must improvise to find ways to mark flowers and prevent further pollination. The petals fall off after a week or so and this provides an opportunity to discuss why the petals are so bright and why the fall. The seeds mature in the ripening ovary over the next few weeks. When the ovary splits, students count the seeds and plant them. Number of seeds and germination rates are recorded.
Students write a Lab Report that includes their hypothesis, results and conclusions. Student logs are also considered. Some classes analyze their own data and class data statistically.
Have students bring in their own soil, test it for pH, N, P, K and add what is necessary. Seeds can be planted in both nutrient deficient and remediated soil. Water pH can also be measured.
Questions about where these bulbs grow in the wild leads to research involving geography, natural pollinators, consequences of loss of this pollinator, symbiosis, flower-insect evolution and many more.
We borrow a digital camera and photograph the flowers, then use them in computer composed lab reports. These lab reports, I find, are well written because the students really get to know their subject well.
Pollen grains can be viewed under the microscope and compared with other types of pollen. In addition, a few petals can be mashed and run through paper chromatography to separate the pigments.
By graphing the daily height of their plants on one graph and the rate of growth (increase per day) on another, students can understand the difference between these two concepts when they encounter them in less tangible situations like enzyme reactions.
- Requires no special equipment and is inexpensive if you save the bulbs from year to year.
- Gives students practice in using the scientific method, hypothesizing, predicting, and problem solving.
- Is a great way for students to learn about plant reproduction, plant anatomy, hybrids, and best of all, they see how seeds are formed and where they come from. They seem to connect with growing things. In addition, it gives us examples of monocots and brightens the room.