POMACEAE 203 



The species of Crataegus occur in a considerable variety of 

 habitats, but seem to prefer rather thin soils, and are most numer- 

 ous in limestone regions. They are probably sensitive to fire, for 

 most of them grow in places pretty well protected from fire. Many 

 if not most of them are found only in clearings, pastures, old 

 fields, along roadsides, etc., and the significance of this will be 

 discussed farther on. 



The treatment of this genus in botanical literature has under- 

 gone a remarkable development in the last few decades. Chap- 

 man's Flora of the Southern United States (first edition, 18(30, 

 second edition. 1883) enumerates only 11 species, and the sixth 

 edition of Gray's Manual of Botany for the northeastern states 

 (edited by Watson & Coulter, 1890) only 10 native species, 2 in- 

 troduced species, and 3 varieties. In Sargent's ponderous Silva 

 of North America (Vol. 4, 1892) it is stated that there are about 

 forty species of Crataegus known, about equally divided between 

 the Old World and the New. Fourteen species and four varieties 

 were described from the United States, and there were said to be 

 at least three others in Mexico. Most of the United States species 

 listed at that time were described in the 18th century, and only 

 one as late as 1880. 



What might be called the Crataegus boom of the end of the 

 19th century may be said to have had its beginning in the descrip- 

 tion of two new species from Northwest Georgia by Dr. A. W. 

 Chapman (then in his 83rd year) in the supplement to the rare 

 1892 edition of his southern Flora. One from the Rocky Moun- 

 tains was described by Greene in 1896, and one from the north- 

 eastern states by Britton in 189T. Shortly after that C. D. Beadle 

 of the Biltmore Herbarium began describing supposed new species 

 of this genus collected by himself and assistants in various parts 

 of the South, and Prof. Sargent did likewise with material from 

 other parts of the country. Britton and Brown's Illustrated Flora 

 of the northeastern states and Canada (Vol. 2, 189T) lists only 15 

 species (trees and shrubs), but signs of the incoming tidal wave 

 (so to speak) w^ere beginning to appear, and the first edition of 

 Sudworth's Check List of trees of the United States, in the fol- 

 lowing year, enumerates about 25 (trees only). 



In 1902 there appeared a supplementary volume (13) of Sar- 

 gent's Silva, containing among other things descriptions of about 



