1. Obtain a soaked bean seed, 2. Remove the seed coat to reveal the two cotyledons which are the prominent internal structures. Carefully separate the two cotyledons and observe the embryo held between them. Draw the opened seed, labeling the cotyledons, the plumule, and the radicle. In this type of seed very little endosperm tissue is present and it is not readily apparent.
2. Obtain a soaked corn grain. This grain is actually an entire fruit, because the outer layer is ovary tissue which has become fused to the seed coat of the seed it encloses. Use a razor blade to longitudinally split the soaked grain. Label the endosperm and the embryo. In this type of seed the cotyledons are small, and the endosperm is the primary nutrient source.
Place a drop of iodine solution on the cut surface of the grain. What storage substance is clearly present in the endosperm of the grain?
3. Examine a prepared slide of a corn grain, 2. Draw the grain, and label the cotyledon, plumule, coleoptile, radicle, coleorhiza, and endosperm.
4. Study the fruits available on display to familiarize yourself with some of the fruit types described in the previous key.
5. Several fruits will be provided by your lab instructor for your examination. For each of these, determine the following characteristics and record them in the table provided by your lab instructor:
A. The composition of the fruit - is it true or accessory?
B. The origin of the fruit - is it simple, aggregate, or multiple?
C. The texture of the fruit - is it dry or fleshy?
D. The specific type of fruit - achene, berry etc.
E. By what type of placentation pattern exhibited by the ovules and their attachment to the ovary?
Axile, parietal and free central placentation types can be viewed here. A cross section of axile and parietal placentations can be viewed here.
F. Try to determine how many locules are present in the fruit and add that as a comment?
Examples of ovaries with various locule numbers can be viewed here.
There may be additional comments by your instructor about the fruit provided.
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