TWO DWARF SPECIMENS OF ARBOR VITAE 



The specimen at the left, which is only six inches high, was growing in a crevice of rock. It is 

 a mature tree, as is proved by the fact that it is bearing two fruits, which can be seen on a 

 square of black paper which was put in for a background. The one at the right, which 

 is not as high as an ordinar\' compound microscope, is over 50 years old; the notch at the 

 base shows where sections were removed to make possible a count of the annual rings. 

 The dwarfness of these specimens is not due to heredity, but merely to the fact that they 

 have never had enough food. (Fig. 4.) 



Nanism due to scarcity of nutritive 

 substances, according to Sorauer, affects 

 the number of blossoms in flowering 

 plants, the number of flowers being 

 considerably reduced. Instead of a 

 cluster or a head, there is often only a 

 single blossom. He further states that, 

 where a greater number of blossoms 

 are formed, single seeds develop which 

 can germinate. 



The same is true among the conifer- 

 ous plants as indicated by the natural 

 dwarfed trees found by the writer. 

 Several trees were found which bore 

 fruit, one of which is here illustrated. 



but the number of fruits formed on each 

 tree was small. On one of the speci- 

 mens here pictured, only two cones 

 were produced. This tree is remark- 

 able in that, though only about six 

 inches tall, the plant was an adult, as 

 indicated by the fruit. The annual 

 rings in this specimen were not counted. 

 The material here described was 

 found upon the rocks close to the water's 

 edge on the shore of Lake Superior on 

 the Keneenaw Peninsula, Michigan, 

 about two miles from Norland. The 

 ecological phenomenon called Krumm- 

 holz was also frequent in the region. 



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