Suggestions for Laboratory and Field Work to Precede 

 Chapter Four 



1. Examine one or more plants from each of the following groups, 

 noting the arrangement of leaves on vertical and inclined stems : 



Corn, elm, hackberry, wheat, rye, canna, bamboo. 

 Lilac, viburnum, catalpa, ash, maple. 

 Willow, poplar, pine, spruce, peach, apple, sunflower. 

 Cat-tail, iris, onion, hyacinth, yucca, century plant. 



2. In the field, study some of the following plants, noting the 

 positions their leaves take with reference to light : 



Sugar maple, elm, beech, oak, catalpa, Virginia creeper, 



Boston i\n^. 

 Tulip tree, cottonwood, birch, willow, spirea, barberry. 

 Which cast the more complete shade, trees whose leaves are 

 sensitive or insensitive to light ? 



3. On several of the following plants study the leaf positions, to 

 determine how the blades reach their positions when mature : 



Sunflower, mallow, Virginia creeper, Boston ivy, English 

 ivy, wild prickly lettuce, nasturtium, ragweed, compass 

 plant, water Hly. Other plants of the locality will furnish 

 additional material for study. 



4. Examine submerged plants like pondweeds, Elodea, Cera- 

 tophyUum, and water buttercups, and compare their leaves with 

 those of land plants. 



5. Sections of leaves of different kinds may be used to show vari- 

 ations in internal structures. 



6. Experiments : 



Grow geraniums and nasturtiums with one-sided illumination. 

 Mark the original position of the leaves with stakes and note 

 changes in position. 



Try the effects of light and darkness on the positions of leaves of 

 sensitive plants, beans, or sweet clover. Black paper covers may 

 be used to exclude the light. 



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