55 



of climatic influences. Thus the tree flora of Florissant during 

 the Miocene was rich in types now lacking in Colorado. Some 

 of these, as Ficus, Sequoia and Magnolia, could not now exist in 

 this region. Others, however, apparently could live well enough, 

 and do so in cultivation. We thus see that the present flora. is 

 to be explained partly by present conditions, but largely also 

 by those of the past, which led to the regional extermination of 

 certain types. The ecologist who concerns himsslf only with 

 the present is thus like a sociologist who should refuse to study 

 history. 



The question has often been raised, how far can we trust the 

 determinations of the paleobotanists? Undoubtedly many of 

 the generic references are erroneous; even Lesquereux, who was 

 not only a great paleobotanist, but also a specialist in living 

 mosses, described a fragment of a fossil conifer as a moss. Never- 

 theless, very much may be learned from the fossils, and there 

 can be little doubt that on the whole things are pretty much 

 what they seem to be. I believe that a closer study of the 

 Tertiary fossils will throw much light on the origin of elements 

 in the modern floras of North and South America, especially 

 when the results of Dr. Berry's recent trip to the Andes are 

 made available. Thus, it is very interesting to find abundant 

 remains of apparently quite genuine Cunoniaceae (Weinmannia) 

 and Proteaceae in the Rocky mountain Miocene. Whence 

 came these southern types? I believe via Asia, rather than by 

 way of South America. So also with Porana, an old-world 

 type fossil at Florissant, but represented still by a stranded relic 

 south of the Mexican boundary. So also with Ailanthus, 

 Lihocedriis, etc. Take up the genuinely neotropical flora, that 

 which certainly originated in South America, and note the 

 absence oi innumerable striking types in our fossil floras. A good 

 example is Cecropia, which has some 30 or 40 neotropical species 

 to-day, and would be easily recognized. 



Another problem is that of the herbaceous plants. A well- 

 known naturalist wrote me the other day, discussing a problem 

 of animal distribution on the supposition that the grass-like 

 plants first became abundant and well developed in the Miocene. 



