THE MIOCENE TREES OF THE ROCKY 

 MOUNTAINS 



PROFESSOR T. D. A. COCKERELL 

 University of Colorado. 



The living arborescent flora of the Rocky Mountain 

 region is at the present time occupying the attention of 

 a number of able workers, including Nelson in Wyoming, 

 Rydberg of the New York Botanical Garden, Sudworth 

 of the Forest Service, Ramaley, Bethel and Schneider in 

 Colorado, Wooton in New Mexico, and others. As a re- 

 sult of all this activity, we are promised two manuals of 

 Rocky Mountain botany, and a third of trees alone, so 

 we shall have three separate and independent treatments 

 of our woody flora to compare and choose from. 



Unfortunately, those who have been so active and ex- 

 haustive in their investigations of the living flora have 

 not cared, as a rule, to consider the historical or paleo- 

 botanical side of the subject, Many "recent" botanists 

 seem to have a positive dislike for fossil plants, and few 

 manifest any great eagerness to receive information 

 about the ancestors or predecessors of the species which 

 occupy their attention. Like all enthusiasts, the writer 

 is filled with the idea that the matter has only to be ade- 

 quately presented to command universal attention; and 

 hence offers this discussion, not so much for the paleo- 

 botanists as for those students of living plants whose 

 active interest may be aroused in the problems involved. 



Going back from the present time, we are practically 

 without information concerning the plants of our region 

 until we come to the Florissant beds, assigned to the 

 Miocene. These beds, however, contain an abundant 

 series of remains, many of the plants beautifully pre- 

 served, as the accompanying illustrations show. They 

 testify to a climate both warmer and damper than that 

 of the present day, the arborescent genera including 

 Sapindus, Ficus, 1 Diospyros, Persea, Leucaena, Anona, 



1 The determination of Ficus is based on the leaves. In confirmation of 

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