Dec, 1910.] Leaf Markings of Certain Ohio Plants. 245 



The plants of the greatest interest are those with definite, 

 often sx'mmetrical patterns, which can have no relation to the 

 general structure. For here we come face to face with the dififi- 

 cult problem of symmetrical coloration in general. Oxalis 

 grandis has beautiful leaves with an ornamental brown margin. 

 Euphorbia marginata has milk-white bands on the leaves sur- 

 rounding the flower clusters. In the second example the claim 

 might be made that the striking color patterns around the flowers 

 were developed through insect selection. In the first case such 

 an explanation would, of course, be out of the question. In 

 Euphorbia maculata and E. nutans, the leaf blades have an 

 irregular oval dark-red spot in the center, the latter species having 

 in addition the white streak over part of the midrib, as mentioned 

 above. Some individuals of Eu])horbia nutans do not show the 

 red spot. 



Trifolium pratense and T. repcns 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, elongated spot 

 in the middle of the leaf on the upper side while P. virginianum 

 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 extending in the 

 direction of the tip of the blade. In some individuals the leaves 

 show no markings. The leaves of Polygonum persicaria have a 

 very definite dark reddish or brownish 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 sagitate in outline. Such leaves are 

 among the most fantastic in design to be observed and well 

 deserve careful study. 



It seems out of the citicstion to attempt to explain the origin 

 and presence of ornamental and symmetrical patterns on leaves 

 from the standpoint of utility. We are led to the position that 

 there are both useful and useless structures developed in plants, 

 the useless markings under consideration not representing degen- 

 erations. By no exercise of the imagination could one see in 

 these designs and patterns any use to the possessor. The}' 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 fonns 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 into the 

 camp of the utilitarians. But the philosophy of life has many sides 

 and the recent discoveries in Mendelian inheritance, mutation 

 and orthogenesis have revealed some of its complexity. 



