CLASSIFICATION OF THE COMMON SEEDS 227 
study of the bean and corn seeds shows the important parts 
of seeds and explains the chief differences between them. 
Some common seeds are classified as follows: monocotyle¬ 
dons, e.g. corn, grass, wheat, barley, rye, oats; dicotyledons, 
e.g. bean, squash, morning glory, tomato, radish, and beet. 
LABORATORY STUDY OF BEAN 
Draw a bean in an upright position, holding the side towards you that 
has the hilnm (a mark) on it. Label hilum. Near one end of the hilum is 
a small dot, the micropyle. Around the outside of bean, lengthwise, 
is a band or ridge, the raphe, ending at the hilum. Label micropyle and 
raphe. Split a soaked bean along the back. Draw the two parts. 
Label them cotyledons. On one of" them is the embryo or young plant. 
Draw and label: (1) the pair of small, white leaves, the plumule or seed 
bud of the new plant; (2) the hypocotyl, below the plumule, from which 
stem and roots will grow; (3) testa, the hard covering. 
Note. — Beans for class work should be soaked overnight at room 
temperature or for two hours in warm water. 
Beans should be first soaked for several hours, then planted about a 
week before the lesson on seedlings. 
Remove most of the cotyledons of a bean embryo. Place it in 
the earth or damp sawdust beside one which has whole cotyledons. 
Make sketches at each laboratory period to show the difference. What 
does this experiment show? Repeat the experiment with other seeds. 
SUGGESTIONS FOR HOME WORK 
Place a few beans in dry sand in a warm room. Why do not the 
beans grow and sprout? Place others in water in a warm room. 
What happens? Place other beans in moist earth (a) in a warm 
room; (b) in a cool place. Examine in a few days. These several 
experiments show the influence of temperatures, soil, and moisture on 
the sprouting of beans. Heat a few beans in an oven for 30 minutes 
and then place them in a warm, moist soil. Why do they not grow? 
Soak beans for 24 hours. Remove the testa and place them beside 
dry beans for a few days. What happens? This experiment illustrates 
one use of the testa. 
Remove most of the endosperm from a few kernels of corn. Plant 
these and compare the seedlings from time to time with those from 
whole kernels planted at the same time in the same dish. 
