342 BOOKS AND CURRENT LITERATURE 



evidence of flowers and fruits is lacking: Cupressinocladus for vegeta- 

 tive shoots of conifers of a cupressoid habit: and Pityites for abietineous 

 fossils of uncertain generic relationship. There is but slight profit in 

 compounding confusion and although a conservative attitude is war- 

 ranted in dealing with the vegetative remains of conifers there is but 

 slight evidence in the more recent history of the study of fossil conifers 

 to show that stem anatomy or strobilar morphology furnish any easier 

 read or more definite criteria than vegetative habit, and from the nature 

 of the remains we cannot hope to have all of the criteria in individual 

 cases. Even the older students in dealing with foliar impressions were 

 not guilty of more pretentious absurdities than have been put forward 

 under the banner of anatomy during the past decade. 



The present volume contains 190 illustrations, which on the whole 

 appear rather uniformly better than those of volume III although it is 

 difficult for the reviewer to understand why paper and presswork were 

 wasted on such illustrations as that forming the frontispiece of the 

 present volume. The bibliography, which has a certain air of com- 

 pleteness, really contains not more than about twenty percent of the 

 literature, but perhaps this should not be criticised since it avowedly 

 contains only "papers and works referred to in the text." 



On the whole it seems to the reviewer that Professor Seward has 

 performed a difficult task about as well as could be expected, and de- 

 spite their obvious shortcomings, which have been freely criticised, 

 these four volumes are a mine of information for the student interested 

 in the floras of the past. — Edward W. Berry. 



Ecology of Roots. — The importance of the distribution of root 

 systems has long been appreciated, and ecologists have realized that 

 the subterranean organs of plants are quite as important as the aerial 

 parts in determining the relation between the plant and its environ- 

 ment and between associated plants. The study of root systems has 

 been delayed, however, by reason of the active exercise which must 

 precede even the simplest observations of their extent and character. 

 A few important pieces of work have been done in recent years, to 

 which Weaver has just added a notable contribution. 1 An investiga- 

 tion extending over several years has resulted in the examination of 

 1150 individual root systems in eight plant communities in Nebraska, 

 Washington, and Colorado. The distinctive root habits of 140 species 



1 Weaver, John E. The Ecological Relations of Roots. Carnegie Inst. 

 Wash. Pubn. 286. Pp. 128, figs. 58, pis. 30. 1919. 



