Brown.:: THE GENUS CRATAEGUS 259 
bridize ; species in several other genera of the rose family hybridize 
freely. During the spring of 1908, I pollinated a few Crataegus 
monogyna (English hawthorn) flowers with pollen from C. Brain- 
erdi, a native species. They set fruit which matured. During the 
flowering season of 1909, Mr. William Moore and the writer made 
cross pollinations between the majority of the native species of the 
local flora.. Most of these cross pollinations were effective, — 
fruit set and matured, being entirely normal apparently. (These 
experiments are still in progress, the details of which will be pub- 
lished later.) 
Within the past few decades, since the primitive forests have been 
cleared away, there has been an immense increase in the number of 
Crataegus plants growing. Being low trees or shrubs they cannot 
thrive in dense forests but spread freely over open pastures and 
along fence rows. The pasture southeast of the campus of Cornell 
University, a field of some twenty or twenty-five acres, has at least 
a thousand plants. This field has been allowed to run to pasture 
for the last twenty-five years or more, and Cyataeg? have thriven 
well. The original forest was cleared away years ago. The in- 
crease in number of plants makes cross pollination easier and 
much more probable. Bees and other insects swarm about the 
trees when they are in blossom, going from flower to flower and 
from tree to tree. 
Irregularity in the number of stamens and pistils, variation in 
the shape of the leaves on the plant, variation in the color of the 
anthers (colors ranging from nearly white to dark purple inter- 
grade), and the occurrence of plants possessing characters found 
in two distinct species growing near by, may all be taken as 
evidence of hybridity or progressive species. Numerous local 
species is another indication. There is scarcely a state that 
has not some species not found elsewhere; many of the species 
found in this immediate locality are different from species found 
at Rochester. 
The fact that Crataegus plants seem to come true to type when 
grown from seed is a stumbling block in the way of a hybridity 
theory. However, it is possible that Crataegus hybrids are stable 
and come true to type when grown from seed. It cannot be said 
that they have been tested thoroughly until many mature plants 
have been grown. 
