THE AMERICAN BOTANIST 9 



the midrib, as mentioned above. Some individuals of Eu- 

 phorbia nutans do not show the red spot. 



Trifolinm pratense and T. re pens have light-colored orna- 

 mental markings on the three leaflets which together make a 

 very striking and symmetrical design. Oxalis violacea often 

 has a similar marking on the leaflets but it is red or purple in 

 color. 



- Polygonum lapathifolium has a faint, irregular, etengated 

 spot in the middle of the leaf on the upper side while P. vir- 

 ginianum has somewhat similar dull reddish spots in the 

 center of the leaves. In Polygonum pennsylvanicum, the leaf 

 has a dark-colored sagitate spot in the center, the point ex- 

 tending in the direction of the tip of the blade. In some in- 

 dividuals the leaves show no markings. The leaves of Poly- 

 gonum persicaria have a very definite dark reddish of brown- 

 ish oval spot in the center. Occasionally one finds individuals 

 having in addition a distinct band of the same color running 

 along each margin. The central spot may also be slightly 

 sagittate in outline. Such leaves are among the most fantas- 

 tic in design to be observed and well deserve careful study. 



It seems out of the question to attempt to explain the or- 

 igin and presence of ornamental and symmetrical patterns on 

 leaves from the standpoint of utility. We are led to the posi- 

 tion that there are both useful and useless structures develop- 

 ed in plants, the useless markings under consideration not 

 representing degenerations. By no exercise of the imagina- 

 tion could one see in these designs and patterns any use to the 

 possessor. They have probably come about through mutative 

 changes and represent elementary species. The beautiful colors 

 and patterns are of as much use to the plant as the beautiful 

 colors and forms are to a rock crystal or to a snowflake. 



Because of the numerous purposeful and useful structures 

 and functions exhibited by organisms, biology was misled far 



