Dec., 1910.] Leaf Markings of Certain Ohio Plants. 
2 45 
The plants of the greatest interest are those with definite, 
often symmetrical patterns, which can have no relation to the 
general structure. For here we come face to face with the diffi- 
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 Euphorbia nutans do not show the 
red spot. 
Trifolium pratense and T. repens 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 question 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. 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 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. 
