1 84 UNIVERSITY OF COLORADO STUDIES 



mesophytic conditions are reached. Here only are there plant asso- 

 ciations which resemble those of the northeastern United States. 



Along the streams, especially the swifter parts of their courses, 

 grow birches^ and willows. If the word "birch" brings to the mind 

 of the reader thoughts of the paper birch of our eastern and central 

 states, then he will have an erroneous idea of the trees at Florissant. 

 The birches and willows are low trees or shrubs, and they form small 

 thickets. In these thickets grow gentians and various orchids, though 

 never in great numbers. Around the margins of the thickets grow 

 the single-flowered harebell^ and the star-flowered false Soloman's 

 seal.^ In this same moist soil are other northern plants, such as the 

 shrubby cinquefoiH and western mint,^ and different species of the 

 sedge and crowfoot famiUes. In the places more open, but still moist, 

 there is a curious wide-spreading thistle.^ The leaves form a dense 

 rosette on the ground with a spread of two feet or more. No upright 

 stem occurs, and the small flower-heads are partly concealed by the 

 incurved leaves. 



To get a proper understanding of the plant population of any region, 

 it is often as useful to know what plants are lacking as it is to know 

 what plants are present. If we compare the Florissant region with 

 the mountain districts of New England or the middle Atlantic states, 

 we shall find many differences. In the Florissant region, and for 

 that matter everywhere in Colorado, there are few trees except cone- 

 bearers. There are no nut-bearing trees. Walnuts, butternuts, 

 hickories, chestnuts, and beeches do not extend into Colorado. Hard 

 maple, elm, and ash are absent, as well as other familiar forest trees 

 of the eastern United States. There are no laurels and rhododen- 

 drons in the Colorado mountains. In fact, it is only in flowering herbs 

 that our mountains excel. But these make up for all deficiencies. 

 BrilHancy and abundance of color make the hillsides and canyon- 

 slopes beautiful all summer. 



' Belula fontinatis. 3 Vagnera stellafa. 



' Campanula uniflora. * Dasiphora fruticosa. 



s Mentha canadensis rubellus Aven Nelson. 



* Carduus acaulescens. A photograph is reproduced in the accompanying plate. «h 



