Brown: THE GENUS CRATAEGUS 255 
species and groups based on the number of stamens are not valid, 
since I am now pretty sure that forms of some species may have 
either ten or twenty stamens. 
5. Some of the species probably originated as mutations. The 
limit of fluctuating variation is undoubtedly wide in some groups, 
but there is frequently a correlation of characters in the species 
which in their stability suggests elementary species rather than 
more instable variation of mutation. Some of the forms in the 
Molles group, in Missouri and Illinois, would seem to be muta- 
tions, leading to the inference that some species of this group have 
originated in this manner. The variation in the Prainosae in the 
Appalachians and the localized valley species also indicate mutation 
origin. 
C. D. Beadle, director of the Biltmore Herbarium, at Biltmore, 
N. C., has made an extended study of southern forms of Crataegus. 
His answers are as follows: 
1. It is necessary to know the complete history of the Crataegus 
species before an understanding of its status is possible. A parallel 
is well typified in the study of Viola, where a knowledge of the 
complete vegetative phases of each species must be understood in 
order to differentiate them. The earlier systematic botanists 
worked largely in the herbarium. The opportunity of dissolving 
the mysteries of the Crataegus genus may be gained only in the 
field and by studying groups of marked trees. 
2. Yesand no. There is a large number of Crataegus species 
undoubtedly ; and, no doubt, there is much duplicating in the 
specific publications by the different authors who are working 
altogether too independently of each other’s discoveries. 
3. Yes, I proved that they come true to seed before daring to 
publish a new species in this field. 
4. Very probably they hybridize. 
5. Yes, they are mutations. 
W. W. Eggleston, of the New York Botanical Garden, is 
another distinguished student of the genus. He has studied the 
specimens in all of the larger herbaria of the country, the living 
plants in the different arboreta, and for a decade or more he has 
been making an extended study of plants in the field in various 
