9 



(c) Take the earlier leaves of the mullein, the plantain, the shep- 

 herd's purse or the dandelion. Work out first the "rosette" arrangement. 

 Then lead up to various arrangements for preventing shading. In the 

 hands of the skillful teacher, this should not be a difficult task. 



(d) The case of lohed and dissected leaves had perhaps better be 

 illustrated by the teacher. The common ivy, star cucumber, or any 

 convenient plant with lobed or angled leaves will be found suitable. 



3. The general form of the plant as determined by the leaf. 



(a) To show pyramidal form of simple plants with entire leaves, 

 take the common mullein, the shepherd's purse, or any plant growing 

 in your region having entire leaves. Have lines drawn from the tip of 

 top leaf to the tip of bottom leaf. What is the shape of resulting 

 figure ? 



(b) To show cylindrical form of plants with dissected leaves, take 

 the rag-weed, or any form easily obtained, and proceed as in (a). In 

 both cases plants of as many kinds as possible should be examined in 

 order that the plant form as determined by the leaf may be seen to be 

 the rule and not merely a chance outline. Plants in which branching 

 does not occur or in which it is very simple should be chosen, as 

 branches complicate the plant outline and render this point more dif- 

 ficult to work out satisfactorily. 



4. The leaf as indicating differing soil conditions. 



(a) Select any water or marsh plants with entire or nearly entire 

 leaves. Suitable forms are waterlily, splatter dock, arrow leaf, skunk 

 cabbage, or marsh marigold. Have them examined with reference to 

 size, toughness and thickness of outer covering of leaf, and presence or 

 absence of hairs. 



(b) Select forms of plants loving dry ground, such as the golden- 

 rods, mustards, some of the smart-weeds, indeed any form growing in 

 dry soil, whether its name is known or not. Examine as to same points 

 as in (a). Compare conditions found in (a) with those in (b). 



(c) Take some single form, such as the wild rose, which you find 

 growing in moist soil, intermediate soil, and dry soil. Note changes 

 in leaf size, leaf number, character of outer covering and presence or 

 absence of hairs, in specimens growing in these different conditions. 



5. Experimental Work. 



1. To show necessity of light for the development of leaf green. 

 (a) Take two plants, equally vigorous, and place them in pots. 

 Keep one in the sunlight, the other in the dark. Let all other condi- 

 tions be identical. At the end of a week or ten days what differences 

 are noticeable in the plants? 



