Plant and Animal Care
Plant and Animal Care: Seeds
Background. The terrestrial plants used in the FOSS program are varieties that have been developed as food sources for humans and the animals humans raise: alfalfa (a legume), barley, corn, bean, pea, clover, radish, rye grass, wheat, oats, and sunflower. Students encounter them as seeds and grow them in a variety of environments. As mundane as these seeds are, they hold the most powerful message on earth: each can develop into a living replica of its progenitor from the genetic message carried in a single cell.
Seeds carry a tiny embryo of the new plant, and a food supply that will nourish and fuel the first few days of life. The two pulpy halves of the bean store the food for the seedling, and it is these same food sources that we use for food when we eat beans. These food storage units, the cotyledons, are found on every seed. Sometimes they are tiny, as in clover seeds, and sometimes they look strange, as in the wrinkly meat of the walnut, but the function is always the same. Plants that have two cotyledons are classified as dicots.
Far more important in terms of their contribution to feeding the world's population of humans are the plants that have only one cotyledon, the monocots. These include grasses, among others; all grains are grasses. The most important food plant is rice, followed by wheat, corn, and barley.
It must be remembered that seeds are living organisms in a dormant stage. Most seeds are capable of resting in this dormant stage for extended periods: 2 or 3 years for most plants, but up to several decades for others. When conditions of moisture and temperature are right, germination, or sprouting, occurs. The seed is capable of growth and development for several days in complete darkness, but after the energy from the cotyledon is exhausted, it must have light or it will starve to death. In the presence of light it can make its own food by photosynthesis.
In the classroom students will be anxious to plant seeds in order to observe one of the miracles of the world. They may not know how to plant, however, and they will need guidance from you. The general rule is that the smaller the seed, the shallower it is placed in the soil. Tiny seeds like clover can simply be spread on the surface of the soil. Large seeds like corn and peas, however, should be planted up to 1 cm (1/2") deep. The general rule for watering is to water when the surface of the soil looks and feels dry, and then only enough to moisten the soil, not to soak it. Students may ask which side of the seed is up. It really doesn't matter much because seeds are programmed so that the root goes down when it emerges from the seed and the shoot goes up.
What to do when the seeds arrive. It's a good idea to test the seeds if the packages have been opened or if the date on the package is more than 2 years old. Plant five of each kind of seed in separate planter cups with soil according to the instructions in each folio. You should get 80% germination. If you get less than four seeds of any kind sprouting, order new seeds.
Ordering seeds. All seeds are packaged in quantities for two class uses. To order more seeds, refer to the FOSS replacement-part catalog. The seeds provided in the FOSS kits have not been treated. If you wish to purchase seeds locally, get seeds that have not been treated with chemicals (such as a fungicide). Treated seeds often have a pink powder on them.
If your students become interested in seeds and want to branch out, go to a nursery and look over the array of seeds. You will be amazed at what is available. Here are a couple of things to look for.
Seek out fairly large seeds. They are easier to handle and count.
What to do with the plants when the investigation is completed. One word of caution involves the attitude that students will have toward their plants. They will probably become very attached to their plants after caring for them for many days. In each activity it is necessary to sacrifice the plants to look at roots or weigh the products. Be prepared. Offer students the opportunity to replant and take the plants home. Or have them set up extras at the start—some to keep and some to study. It is an opportunity to have discussions about respect for life and care for all living things.
The plants could be transplanted into a pot or garden but might not survive the transition. Unwanted plants can be put in a compost. Extra seeds can be returned to their packet and a plastic bag, and stored in the kit in a dry location.