BULLETIN NO. 42. 
Hawthorns have been largely planted in the Arboretum and many 
of these interesting trees and shrubs are now in flower. The principal 
collections are between the boundary wall of the Arboretum and the 
Shrub Collection near the Forest Hills Gate, and on the eastern slope 
of Peter's Hill. The multiplication of the species of Hawthorn (Cra- 
taegus) in eastern North America is remarkable, and nowhere else be- 
yond the tropics is there a genus of woody plants represented by so 
many distinct forms. Much attention has been given at the Arbore- 
tum in the last fourteen years to the collection, study and cultivation 
of these plants, and some three thousand lots of seeds of wild plants 
from different parts of the country have been planted. Among the 
seedlings raised are, of course, many duplicates, but between six and 
3even hundred species raised in the Arboretum are now established on 
Peter's Hill where plants of between fourteen and fifteen hundred of 
the seedling numbers have been planted in small square beds. Many 
of these plants are already flowering, and this collection promises to 
be in a few years one of the important features of the Arboretum 
both from an educational and an ornamental point of view. It w T ill 
now repay examination. 
The American species of Crataegus fall into some twenty natural 
groups, and on Peter's Hill the. species of the different groups are arranged 
together. In eastern North America Hawthorns are distributed from 
Nova Scotia and the valley of the St. Lawrence River to central Flor- 
ida and western Texas. The number of species is greatest, perhaps, 
in the territory adjacent to Lake Ontario and the streams flowing into 
it. They are very numerous in the St. Lawrence Valley, in the lower 
peninsula of Michigan, in southern Missouri and Arkansas, and in the 
foothill region of the southern Appalachian Mountains. The genus is 
poorly represented in the Rocky Mountain region and reaches the north- 
west coast with a single species. Some species are found over thous- 
ands of square miles; others are very local. The American Hawthorns 
vary greatly in size; some species are trees which on the fertile bot- 
tom-lands of streams flowing into the lower Mississippi River are 
sometimes wide-branched and fifty or sixty feet tall, and others are 
shrubs often not more than two or three feet high. In the Arboretum 
some species begin to flower at the end of April or early in May and 
it is the middle of June before the flowers on some species open. No 
plants hardy in New England produce such abundant crops of beautiful 
fruits. The fruit of some species ripens in August and from August 
until November there is a succession of ripening fruits on some of the 
plants; and on some species the fruit remains in good condition during 
the entire winter. The species which flower the earliest belong to 
what is called the Mollis Group from one of its species. These are 
shapely and often large trees; they all have large flowers, large leaves 
and large, brilliantly colored and often edible, usually scarlet fruits. 
Examples of this group are Crataegus Arnoldiana, first found grow- 
ing wild in the Arboretum, and C. arkansana from northern Arkansas; 
both of these trees can be seen in the group near the Forest Hills 
Gate, and C. Arnoldiana has been largely planted in different parts of 
the Arboretum. Of C. arkansana there is a large specimen on the 
