THE GENUS CRATAEGUS IN COLORADO 
By T. D. A. COCcKERELL 
A few years ago the writer began a study of the thorns growing about 
Boulder, and sent some material to Dr. Sargent, the well-known authority 
on this genus. It was hoped that the local forms would be readily identi- 
fied, but numerous difficulties presented themselves. Not only were 
the several kinds very closely allied, but the existing descriptions— 
which were quite numerous enough to cover all the known forms—proved 
to be seriously inadequate. The best of them, by Professor Aven Nelson, 
were unfortunately the latest to be published, and there was little doubt 
that the plants should be known by the earlier designations of Britton? 
and Ashe.? Dr. Rydberg’s account of Crataegus, in his excellent Flora 
oj Colorado, did not clear up the difficulties, and unfortunately contained 
one or two serious errors. 
No revision of the Colorado Crataegi is to be thought of at present, 
I offer instead merely a summary of the characters given in the original 
descriptions of the six supposed species founded on specimens from the 
foothills of the front range of northern Colorado, and a list of the species 
known from the state, as at present understood. The characters given 
in the descriptions are presented as originally written, so that the reader 
may have before him all the information provided by the original authors. 
It is hoped that students throughout the state will examine the Crataegi 
of their vicinity in the light of these descriptions, and that with their 
co-operation it may be possible eventually to put the subject on a sound 
basis. In the study of these plants, it is especially important to secure 
flowers and fruit from the same trees, which should be marked to prevent 
mistakes. It is also very important to note the color of the anthers 
in fresh flowers. 
Mr. Eggleston of the New York Botanical Garden has examined all 
-Nelson’s types, as well as that of occidentalis Britton, and has kindly given 
me some important information. He has also found some reliable 
t Bull. N. Y. Bot. Gard., 1, 448 (March 30, 1900). 
2 Bull. 175, N.C. Agric. Exp. Sta., 110, 113 (Aug., 1900). 
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