Books an d Ci i k r e n t J a X B r at ukk. 



in no wise typical of the prairie province. The latter class of 

 plants was usually semi-xerophytic, and occurred in the uplands. 

 What is the" significance of this? Does it throw any 'light liipon 

 the order of entrance of plants, and of western plants in particu- 

 lar, into this area? 



" 4. The occurrence of prairie species beyond the eastern 

 limits of the province suggests a search for such relict colonies, 

 to determine the former maximum extension of the prairie. 



5. Is it possible that there was a post-glacial period with 7 

 so little rainfall that the distribution of certain plants now 

 occurring at widely distant stations along the Illinois River 

 and in Nebraska and Dakota was formerly continuous over the 

 wliole desert-like intervening territory? 



6. What was the structure of the original prairie associa-? 

 tions? Probably the time has passed when this question could 

 have been satisfactorily answered. f o 



7. The normal succession for prairie associations has-not 

 yet been fully investigated * * * In this region^ the forest! 

 is everywhere pushing out upon the prairie. We are ignorant 

 of the factors which tend to retard or accelerate the advance of 

 the forest, or of the nature of the tension zone between the two 

 associations, or of those particular species which may be called 

 pioneers in the forest advance. 



Wild Flowers and Trees of Colorado, by Professor Frances 

 Ramaley, is a very convenient and beautifully illustrated little 

 book of 78 pages. The first part is a short essay on the plants 

 of Colorado — their habits, distribution, and relation to altitudie 

 Examples of the most interesting species of flowering plants from 

 different altitudes are described and figured The second, half 

 of the book is devoted to forest formations and forest trees. 

 Keys are given for the determination of all the native trees of the 

 state, together with notes regarding their distribution and 

 grouping into formations. 



Rocky Mountain ^Wildflower Studies, by Professor H . O 

 Longyear, of the Colorado Agricultural College^ has .-.recently 

 appeared. A copy has not yet been received by the Plant 

 World, but it is described as "a charmingly written series of 

 Colorado nature sketches." 



