64 STRUCTURE AND PHYSIOLOGY OF SEED PLANTS 



THE FLOWER OF THE HIGHER SEED PLANTS 



44. The flower of the Trillium. ^ * * 



A. Cut off the flower stalk rather close to the flower ; stand the 

 latter, face down, on the table, and draw the parts then 

 shown. Label the green leaf -like parts sepals, and the white 

 parts, which alternate with these, petals. 



B. Turn the flower face up and make another sketch, label- 

 ing the parts as before, together with the enlarged yellow ex- 

 tremities, or anthers, of the stalked organs called stamens. 



C. Note and describe the way in which the petals alternate 

 with the sepals. Observe the arrangement of the edges of 

 the petals toward the base, — how many with both edges 

 outside the others, how many with both edges inside, how 

 many with one edge in and one out. 



Note the veining of both sepals and petals, observing in 

 which set they are more distinct. ^ 



D. Pull off a sepal and make a sketch of it, natural size ; then 

 remove a petal, flatten it out, and sketch it, natural size. 



E. Observe that the flower stalk is enlarged slightly at the 

 upper end into a rounded portion, the receptacle, on which 

 all the parts of the flower rest. 



F. Note how the six stamens arise from the receptacle, 

 and their relations to the origins of the petals. Remove the 

 remaining petals (cutting them off near the bottom with a 



1 Only one flower need be studied to give an idea of the floral organs ordinarily 

 found. More advanced studies are suggested at the end of Part III. 



If none of the three flowers here described can be had, the instructor can 

 readily frame a set of directions for the examination of some other form. Among 

 the simplest types which can readily be grown in the greenhouse for class study 

 are Sedum acre and Crassula quadrifida. Matthiola is not quite so simple, but 

 the single-flowered varieties answer very well. Scilla sibirica is often available. 

 Another convenient greenhouse flower is the Roman hyacinth. 



2 In flowers with delicate white petals the distribution of the fibro-vascular 

 bundles can usually be readily shown by standing the freshly cut end of the 

 flower stalk in eosin for a short time, until colored veins begin to appear in the 

 petals. The experiment succeeds readily with apple, cherry, or plum blossoms; with 

 white gillyflower the coloration is very prompt. Lily of the valley is perhaps as 

 interesting a flower as any on which to try the experiment, since the well-defined 

 stained stripes are separated by portions quite free from stain, and the pistils 

 are also colored. 



