PROPAGATION BY SEEDS 43 



kernel of corn is cut longitudinally the narrow way of the 

 kernel so that a section similar to the one shown in Fig. 24 

 is obtained, the parts of the seed can be 

 seen. The plumule and caulicle can be 

 seen easily if the tip of each is raised 

 with the point of a knife blade. Sur- I11F ill. J- U MULE 

 rounding the plumule and caulicle is the 

 cotyledon. The part of the seed to the 

 left of the diagonal line in the illustra- 

 tion is not part of the cotyledon, but is 

 stored food material for the use of the 

 young growing plant. 



54. Two classes of plants. Plants whose seeds have two 

 cotyledons, such as the pumpkin, bean, and pea, are known 

 as dicotyledonous plants, while those whose seeds have one 

 cotyledon are said to be monocotyledonous. 



In the plants grown from dicotyledonous seeds, the wood 

 fibers of the stems are arranged in circles and such stems are 

 said to be exogenous, because the growth takes place on the 

 outside as explained in paragraph 41. Plants of this type 

 usually have netted-veined leaves, and the flower parts are 

 in fives or fours or their multiples, and never in threes. Most 

 of our fruit-trees belong to this class. 



Plants grown from monocotyledonous seeds have endog- 

 enous stems with the wood fibers scattered through 

 them as explained in paragraph 41. Such plants have 

 parallel -veined leaves, and the flower parts are usually in 

 threes or multiples of three. All true grasses belong to this 

 type. 



It will be seen that by studying the seeds, flowers, stems, 

 and leaves, it is not only easy to place a plant in the correct 

 class, but to foretell from the seed what kind of stem, leaves, 

 or flowers the plant will be likely to have; or to tell, by ex- 

 amining the stem, leaves, or flowers, from what kind of seed 

 any plant came. 



