REPRODUCTION IN PLANTS 91 



2. Make a drawing, natural size (or an inch in diameter 



in case the grape or cranberry is used), of one 

 half of the fruit, and show method of seed 

 attachment. 



3. (Optional.) Pinch a seed of one of the fruits between your 



thumb and forefinger. Is it hard or soft ? Is it dry or 

 slippery? Of what advantage are these character- 

 istics? 



102. Seed Dispersal. It is evident that stronger plants 

 will be developed from seeds if the latter are carried some 

 distance from the mother plant, for then they will not be 

 shaded by the mother plant, and the young plants will have 

 more light, air, food, and moisture, if they are not crowded 

 together. We shall now study some of the devices by which 

 plants secure the dispersal of their seeds. 



103. Seed dispersal by wind. Laboratory Study No. 48. 

 Study one or more of the following fruits : 



A. Winged fruits. 



1. The maple fruit. 



a. Find the fruit stalk, the two cells of the ovary each 



containing a single seed, the wing attached to 

 each cell of the ovary. 



Hold between yourself and the light a maple fruit 

 in the position in which it hung on the tree, and 

 draw it (X 2). Label fruit-stalk, cell of ovary, 

 containing one seed, wing, veins of wing. 



b. Hold one of the fruits some distance above the desk 



and let it fall. Describe the movements of the 

 fruit in falling. 



c. Of what use are the wings if the wind were blowing 



while the fruit is falling, or after the fruit has 

 fallen to the ground ? 



d. Is the maple fruit a dry or a fleshy fruit ? 



2. The linden fruit. 



a. Notice the wing-like attachment on the fruit-stalk. 

 Do the linden fruits occur singly or in clusters? 



