VI. SEEDS AND SEEDLINGS 



Relation of Flower to Fruit. — We have already found in our 

 study of the fruit that the bean pod is a direct outgrowth from 

 the flower. It is, in fact, the ovary of the flower, with the parts im- 

 mediately surrounding it, which has grown larger to make a fruit. 



Use of Fruit. — The fruit is the most important result of the 

 flower. It holds and protects the seeds until the time comes that 

 they are able to germinate and produce new plants like the original 

 plant from which they grew. 



Study of a Bean. — Let us now take up the careful study of a bean in order 

 better to understand how the seed may produce a young plant. For this 

 purpose we need some dry pods of the string bean and some kidney beans. ^ 



If we have already studied the pod of the bean, it will now be easy for us 

 to find and identify the parts of the pod which were style, stigma, and ovary 

 in the flower. Opening the pod along one of the edges or sutures of the two 

 valves, we find the seeds fastened to the placenta each by the little stalk or 

 funiculus. If we pull a single bean from its attachment, we find the funicu- 

 lus leaves a scar on the coat of the bean; this scar is called the hilum. Look 

 near the hilum for a tiny hole called the micropyle. (Do not confuse it with a 

 little knob called the strophiole.) Turn back to the figure showing the 

 ovule ui the ovary. Find there the little hole through which the pollen 

 tube reached the embryo sac. This hole is called the micropyle, and 

 is identical with the micropyle in the seed. Draw a single kidney bean from 

 the edge bearing the hilum scar, and show exactly the location of the hilum, 

 micropyle, and strophiole. Make the drawing twice natural size. 



Home Experiment. — Divide ten kidney beans of nearly equal size into 

 two lots. Cover the micropyles of one lot with wax or vaseline, weigh 

 both lots of seeds exactly, then leave them in water over night. Weigh 

 both lots in the morning. Note any differences in the appearance of the 

 two lots of seeds. What is one use of the micropyle to the bean seed? 

 This experiment may be made more instructive by covering a third lot of 

 beans completely with wax and exposing them to the same conditions as 

 you did the others. Does any water get in through the seed coats? 

 Remove carefully the coat from a kidney bean which has been soaked over 

 night in water. This coat, because of its toughness, is called the testa. Do 

 you find another coat under it? You find the bean separates into two 

 parts; these are called the cotyledons. If you separate the cotyledons very 

 carefully, you find certain other structures between them. The rodlike 

 part is called the hypocotyl (meaning under the cotyledons). This will later 

 form the root (and part of the stem) of the young plant. Look for the first 



* For extended laboratory study on the bean, see Hunter and Valentine, Manualf 

 page 13. 



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