EXERCISE 29 



Problem. What is there in a seed that becomes a living plant ? 



What to use. Different large seeds (for example, beans, peas, peanuts, cotton seeds, castor seeds, 

 horse-chestnuts), some dry, some soaked l for twenty-four hours ; magnifying glass. 



What to do. Examine outside of seed and note size, shape, and position of scar showing where 

 the seed was attached to the fruit. This is the hilum. Look for a tiny opening through the waterproof 

 'coats (testa), called the micropyle. Examine any other surface peculiarities or structures. 



Carefully remove the seed coats of two different seeds. Notice the two halves of the seed the 

 fleshy seed leaves called the cotyledons. These are joined to a pointed structure called the hypocotyl, 

 part of which grows into the ground and becomes the root and part of which becomes the stem. Note 

 the first bud, usually lying between the cotyledons and attached to both of them at the base. This is 

 called the plumule, or epicotyl. 



NOTE. All the structures inside the coat, or testa, of most of the seeds together make up the embryo, or young plant. 

 Each part of the embryo corresponds to one of the main parts of a full-grown plant. 



Record. Fill out the blanks on the next page with diagrams, making each drawing at least two 

 inches in diameter. Label all the parts for which names are given in the study. 

 Questions. 1. In what way do the cotyledons resemble ordinary leaves ? 



2. In what ways do the cotyledons differ from ordinary leaves ? 



3. How would the hypocotyl have to change to resemble an ordinary root ? 



4. How does the plumule resemble the parts of a plant usually found aboveground ? 



1 Add a few drops of formalin to the water in which the seeds are soaked, to prevent fermentation or decay. 



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