23 
Pennsylvania or west in the United States of Indiana. The Intricatae 
with many species is interesting because most of the representatives 
are small shrubs which until recent years have been entirely overlooked 
by botanists. This Group is widely distributed from Canada to Texas 
and is best represented in Pennsylvania and Michigan; it apparently 
does not occur in the coast region of the south Atlantic and east Gulf 
States; it has not been noticed in Louisiana and is rare, except in 
northwestern Arkansas, in the states west of the Mississippi River. 
Belonging to this Group are many attractive garden plants now grow- 
ing in the Arboretum. In the Uniflorae are only small shrubs 
with small flowers; nowhere very common they are distributed from 
eastern New York to Alabama and Texas. Handsome plants are the 
two shrubs which compose the Triflorae and which grow in the hill 
regions of northwestern Georgia and northern Alabama. The Pulcher- 
rimae, Bracteatae and Silvicolae are small groups confined to the south- 
eastern states, with one species of the Silvicolae in eastern Louisiana; 
these three groups still imperfectly known. The Microcarpae with three 
species are distinguished by their small fruits and by the principal veins 
fo the leaves which extend to the point of the lobes as in other species 
of Crataegus and also to the bottom of the sinuses between the lobes. 
Two of these species, C. apiifolia and C. spathulata, are well scattered 
over the southern states; and the third, C. cor data, the so-called Wash- 
ington Thorn, is a rare and local tree in the region from western North 
Carolina to southern Missouri and southern Illinois. It is hardy in the 
Arboretum where it is the last species to flower. An old inhabitant of 
gardens, it is not surpassed in the beauty of its foliage in autumn or 
the brilliancy of its fruit which remains on the branches until spring. 
The great Flavae Group is distinctly southeastern with many species 
which vary in habit from large trees to shrubs, and are well distin- 
guished from the species of other groups by the conspicuous glands on 
their mostly obovate-cuneate leaves, petioles and corymbs, by their zig- 
zag branches and by the hard dry flesh of their green, orange or red 
fruit. The plants of this Group are very common in southern Georgia, 
western Florida, and southern Alabama, with a single species in east- 
ern Louisiana, near the banks of the Mississippi River in West Felici- 
ana Parish, and with several species in the southern Appalachian region 
up to altitudes of about two thousand feet. This distinct and interest- 
ing Group is well represented in the Arboretum by old trees of Cra- 
taegus aprica from western North Carolina. The Macracanihae, bet- 
ter known as the Tomentosae, is one of the most important eastern 
groups, common with many species in Canada and the northern states, 
but absent from the southeastern states, the coast region of the east 
Gulf States and Louisiana, and very rare in eastern Texas and Arkan- 
sas, but represented in the southern Rocky Mountain region. The fruit 
of some of the northern trees of this group is perhaps more beautiful 
than that of the plants of the other groups. Several species of the 
Macracanihae flower and produce fruit in the Arboretum. The Doug- 
lasianae are black-fruited trees and shrubs of the northwestern and 
interior parts of the continent, with one species in the Lake Superior 
region of northern Michigan. All the species of this Group are grow- 
ing well in the Arboretum, as are those of the Anomalae a northeast- 
ern Group related to the Macracanihae and Douglasianae by the pres- 
