254 Brown: THE GENUS CRATAEGUS 
I. Because they did not use their eyes and were satisfied to 
take for granted that what had been published about the genus 
was correct and final. 
2. I do not know what you mean by elementary species, 
3. We have planted in all nearly three thousand numbers of 
seeds at the Arboretum and so far have found no evidence that 
the different species do not come true from seed. In fact the 
seedlings of no other genus that has been raised here have shown 
such a remarkable resemblance to the parent plants. 
4. We have never found here any evidence that the different 
species hybridize. 
5. I cannot answer this question. 
W. W. Ashe, of the Forest Service, U. S. Department of 
Agriculture, has studied East-American species of Crataegus con- 
siderably. His answers are: 
1. The species of Crataegus were not recognized earlier because 
the material was studied entirely in a dry state, in which distinctive 
characters are very largely lost. It was not uncommon to find in 
the largest collections specimens of most different forms from 
widely separated parts of North America bearing the same name. 
Several groups even were not recognized ; for example, /utricatae, 
all species of which were called “ coccinea.” 
2. Some of the species now being proposed are undoubtedly 
elementary. Most of them, however, are certainly not. The 10- 
and 20-stamened forms with slight accompanying differences in 
fruit, or differences in anther color with slight accompanying 
differences in fruit are clearly elementary species. When differ- 
ences extend to inflorescence, size of flowers, and foliage, the sum 
of the correlated characters may be regarded as entitling the form 
to full specific rank. 
3. Many of the species are known to breed true through their 
seed. Most of them have not been sufficiently tested for conclu- 
sive proof. 
4. Many species hybridize and some of those which have been 
proposed are undoubtedly hybrids. Hybrids are probably no 
more numerous, however, than between the nearly related species 
of American oaks, It is also undoubtedly true that some of the 
