ir KEY AND FLORA 



may be found worth while, in the case of some Umbelliferce, 

 Boraginacece, and Composite, to collect fruit during the sum- 

 mer before it is to be used, preserve it either dry or in pre- 

 servative fluid, as may seem best, and use it with freshly 

 collected flowers in the determination of species. 



No systematic work with seed plants can be of much use 

 unless the teacher takes constant pains to bring out the idea 

 of actual relationship by descent among the forms studied, 

 and to show, in the simpler cases available, some of the steps 

 of evolution. The beginner must not be allowed to suppose 

 that the flora which he is using contains more than a small 

 fraction of the total number of plants even in the families 

 treated. He must be made to realize that the Rubiacece, for 

 instance, of which he has fourteen species described, really 

 number as many as 4500 species, and the Composite, instead 

 of mustering a few dozen strong, number in all at least 12,000 

 species. For such comparisons Engler's Syllabus der Pflanzen- 

 familien will be found to contain the most recent and compact 

 summary. 



A somewhat complete (phanerogamic) flora of the student's 

 region should be constantly in use. For this purpose the 

 author prefers to all others the seventh edition of Gray's 

 Manual of Botany. For the convenience of those who may 

 find it necessary to use Britton's Manual of the Flora of the 

 Northern States and Canada, the generic name used by Britton 

 will generally be found in parenthesis after the name sanc- 

 tioned by the Vienna code. In cases where Britton's genus 

 covers only part of the genus as given in this book, a state- 

 ment to that effect is made, as on p. 186, B. Fl. species 4 

 (Naumburgia). For suggestions about literature see Bergen 

 and Davis, Laboratory and Field Manual of Botany, p. 230. 



The novice should find a good deal of help in understand- 

 ing the structure of some of the more difficult flowers and 

 fruits in the illustrations which accompany several families. 

 Most of these have been redrawn for the present edition by 

 Mr. E. N. Fischer of Boston. 



J. Y. B. 



CAMBRIDGE, MASSACHUSETTS 



