4- THE AMERICAN BOTANIST. 



Rubus setosns as it has been used heretofore. (See 

 Britton's Manual p. 498 and Illustrated Flora fig. 1903.) 

 Mr. Rydberg stouth' argues in a letter to the writer that 

 R. setosus must be restricted to the comparatively rare 

 plant of Eastern Massachusetts which Dr. Bigelow named, 

 and of which spechnens are now preserved in the herba- 

 rium of the New York Botanical Garden. These, I am 

 informed, closely reseinble R. hispidus, L. Mr. Rydberg 

 was plainly not describing a new plant and these plants 

 are here named and described for the first time. 



Those interested in blackberries will find it important 

 to read President Ezra Brainerd's article in Rhodora, 

 (Feb. 1900) and Prof. L. H. Bailey's "Evolution of Our 

 Native Fruits," (1898). 



BOTANY FOR BEGINNERS-XV. 



THE DICOTYLEDONS. 



The Dicotyledons are regarded as higher in structure 

 than the Monocotyledons, and so thej^ are, as a group, 

 but the least specialized of these are exceedingly primitive 

 and not to be compared with the highest Monocotyledons. 

 From the lowest to the highest Dicot\dedons there is a 

 gradual line of development but whether Dicotyledons 

 sprang from Monocotyledons, or the reverse, is not as yet 

 very clear to botanists. One thing is certain : there has 

 been more than one line of development among the plants 

 and the Dicotyledons do not represent a continuation of 

 development from the Monocotyledons. It is probable 

 that the two groups began to diverge along distance back 

 in their history and have since worked out their develop- 

 ment on different lines. 



The Dicotyledons as a whole are not only the best 

 developed of the two groups but contain by far the greater 

 number of species. It is estimated that there are more 

 than a hundred thousand species In this group and most 

 of our familiar flowering plants belong to it. As in the 

 Monocotyledons, the group is separated into divisions 

 based upon differences in the structure of the flower, the 



