STRUCTURE OF THE FLOWER AND ITS ORGANS. 151 



method indicated in Pigs. 133 and 135, but making the longi- 

 tudinal section show the interior of the ovary.^ 



Fig. 135. — Diagrams of Cross-Sections of Flowers. 

 I, columbine ; II, heath family ; III, iris family. In each diagram the dot along- 

 side the main portion indicates a cross-section of the stem of the plant. In II, 

 every other stamen is more lightly shaded because some plants' of the hpath 

 family have 5 and some 10 stamens. 



1 Among the many excellent early flowers for this purpose may be mentioned 

 trillium, blood-root, dog-tooth violet, marsh marigold, buttercup, tulip tree, horse- 

 chestnut, Jeffersonia, ^May-apple, cherry, apple, crocus, tulip, daffodil, primrose, 

 wild ginger, cranesbiU, locust, bluebell. 



