THE SEED 21 



7. What is bran? Does it contain any nourishment? (11, 12; Exps. 1-0.) 



8. What gives to Indian corn its value as food? to oats? wlieat ? 

 rice? (3; Exps. 1-6.) 



9. Which of these grains has the larger proportion of endosperm to 

 embryo ? (Figs. 1-3.) 



10. Which contains the lai'ger amount of starch in proportion to 

 its bulk, rice or Indian corn ? 



11. If you wished to produce a variety of corn rich in oil, you would 

 select seed for planting with what part well developed? (3; Figs. 4-7.) 



IV. SEED DISPERSAL 



Material. — Fruits and seeds of any kind that show adaptations for 

 dispersal. Some common examples are: (1) Wind: ash, elm, maple, 

 ailanthus, milkweed, clematis, sycamore, linden, dandelion, thistle, 

 hawkweed. (2) Water: pecan, filbert, cranberry, lotus, hickory nut, 

 coconut — obtain one with the husk on, if possible. (3) Animal agency 

 (involuntary): cocklebur, tickseed, beggar-ticks, burdock; (voluntary) 

 almost all kinds of edible fruits, especially the bright-colored ones — wild 

 plums, cherries, haws, dogwood, persimmons, etc. (4) Explosive and 

 self-planting : witch-hazel, wood sorrel, violet, crane's-bill, wild vetch, 

 peanut, medick, stork's-bill (Erodium). 



Experiment 17. To show how seeds are dispersed by wind. — 

 Take a number of winged and plumed fruits and seeds, such as those of the 

 maple, ash, ailanthus, dandelion, clematis, milkweed, and trumpet creeper; 

 stand on a chair or table in a place where there is a draft of air and let 

 them all go. Which travel the farther, the winged or the plumed kinds ? 

 Which sort is better fitted to aerial transportation ? 



Experiment 18. Dispersal by water. — Place in a bucket of water 

 a hazelnut, an acorn, an orange, a cranberry, a pecan, a hickory nut, a fresh 

 apple, and a coconut with the husk on. Which are the best floaters ? Cut 

 open or break open the good swimmers, compare with the non-floaters, and 

 see to what peculiarity of structure their floating qualities are due. In 

 what situations do the cranberry and the coconut grow ? Can you see 

 any advantage to a plant so situated in producing fruits that float easily ? 



Experiment 19. Dispersal by explosive capsules. — Moisten 

 slightly some mature but unopened capsules of witch hazel, wood sorrel, 

 rabbit pea, or violet, and leave in a warm, dry place for fifteen to forty- 

 five minutes. What happens when the pods begin to dry ? Measure the 

 distance to which the difl'erent kinds of seeds have been ejected. Which 

 were thrown farthest? What was the object of the movement? What 

 caused the explosion ? 



