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DISSECTING SEEDS Today we will dissect (cut open) some seeds which we have soaked overnight. There are mainly two classes (different types) of seeds: those which divide into two parts, and those which do not. Beans, peas, and peanuts are some of the seeds that divide in half, and they are called "dicotyledons" (pronounced "die-cot-i-lee-don" --say the "lee" part of the word hardest, which is called accenting). Corn, oats, and coconuts are some of the seeds that do not divide in half. They are called "monocotyledons" (pronounced "mon-no-cot-i- lee-dons"). First we will examine some dicotyledons. We have soaked some lima bean seeds overnight, and now we'll put them onto paper towels or paper plates, so the parts will not get lost. When beans have soaked overnight, their skins get wrinkly. That skin is called "seed coat", and we are going to take it off the bean. We'll use a pin or a toothpick (or dissecting needle if we have one), and peel the seed coat off, and put it down onto the paper. See how thin it is! Even though it is very thin and delicate, it protects the seed, and helps hold the halves together. Now that the seed coat is off, we will gently pry at the seam and let the seed divide into its two parts. Each part is called a "cotyledon" (pronounced "cot-i-lee-don). After the seed is divided, you can see a tiny plant inside. This tiny plant is called the "embryo" (pronounced "em-bree- o"). Get a magnifying glass and look closely at the embryo. You can see the root, the stem, and the leaves of the embryo. It really is a very tiny plant! If you open a peanut shell and take out one peanut, you will see that it has a brown seed coat, and that when you take off the seed coat, the peanut divides into two parts. In the middle of the two parts, you will see the embryo. The embryo usually sticks to just one of the two parts, and you will see a dent in the other part of the peanut where the embryo was growing. You don't need to soak a peanut in order to divide it easily. Now we will examine some monocotyledons. We have soaked corn seeds overnight, and, after putting them on paper towels or paper plates, we will remove the seed coat. The seed coat on corn is a little stronger than the seed coat on lima beans. We'll have to use a sharp pin. Be careful not to poke your finger! After you take off the seed coat, you can see the embryo. Look at it with the magnifying glass, and see if it looks like the embryo of lima beans.  Any problems with this page? Send URL to
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