PLANT PROPAGATION 45 



QUESTIONS AND PROBLEMS 



1. Under what conditions for germination may the largest percentage 

 of young plants be expected ? 



2. Why is it that some thick-walled seeds, as those of the cocklebur and 

 honey locust, may lie in the ground for several years before germinating ? 

 How could germination be hastened? 



3. Prepare a list of a dozen common farm and garden seeds and state 

 the depth at which, under ordinary conditions, the best germination may 

 be expected. 



4. What conditions determine the length of life of a seed? 



5. When are seeds said to come true? 



6. What are the disadvantages of planting seeds which do not come 

 true? How are these disadvantages avoided? 



7. Prepare a chart, giving the different methods of propagation, naming 

 a plant propagated by each method, and describing how the plant is treated 

 in each case in order to propagate it. 



8. Of what particular value to man is plant propagation? 



EXERCISES 



1. Stored food of seeds. Examine a dry grain of corn. Locate the 

 heart, or germ. Soak a few grains of corn overnight or until softened. 

 Remove the skin, or seed coat. Is the germ, or heart, united to the 

 remainder of the seed ? Carefully remove the germ and plant it and 

 the rest of the grain in wet sand between cloths. Observe every day 

 and note results. Is all of the grain alive ? Plant some grains of 

 corn that have been soaked for a few hours. When roots have begun 

 to form, carefully remove the main part of the seed and plant again. 

 Plant by the side of seeds that have not been disturbed. Explain results. 



2. Cotyledons. Examine a dry lima bean. Locate the germ. 

 Soften some beans by soaking for a few hours. Plant one-half inch 

 deep, and when they begin to grow, carefully remove the two large 

 seed leaves. Keep accurate measurements of the rate of elongation 

 of both kinds of seedlings, and thus determine the value of the food 

 stored in the seed coats. 



3. Relation of air to germination. Drop ten lima beans into a 

 glass of water. After twelve or fifteen hours examine. Observe 

 again at the end of twenty-four hours. Why did germination cease ? 



