1915] 



BESSEY PHYLOGENETIC TAXONOMY 115 



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28. In diclinous plants the monoecious condition is the earlier, 



and the dioecious later. 



Let us now endeavor to apply these principles candidly in 

 an attempt to secure a phyletic taxonomy of the flowering 

 plants. 



As a consequence, we begin with the plants that are primi- 

 tively opposite-leaved, as shown by their first leaves ("cotyle- 

 dons") that are always opposite. These are what we have 

 known as dicotyledons. But this name, which was once sig- 

 nificant, is no longer useful, and in fact has become somewhat 

 misleading, so that I propose to substitute for it the name 

 Oppositifoliae for the first class of the Anthophyta. Like- 

 wise for the other class, hitherto known as the monocotyle- 

 dons, in which the leaves are alternate from the first, and con- 

 tinue so throughout the whole plant body, I propose the more 

 appropriate name of Alternifoliae. 



In considering these two classes, it is quite evident that the 

 first is not only the larger in the number of its species, but also 

 that it includes many more important modifications of struc- 

 ture than does the other. Yet there is much similarity in the 

 kinds of modification of structure in the two classes, the larger 

 class, from its very largeness, including many more details of 

 modification and variation. 



In both classes we begin with apocarpous plants, and pro- 

 ceed toward those that are syncarpous. So the Ranales on 

 the one hand, and the Alismatales on the other, are near the 

 point of beginning. In one class syncarpy is attained after 

 the passing of a few hundred species {Alismatales, 409 

 species), while in the other it is not reached until much beyond 

 the limits of the order Ranales, for it is well known that the 

 syncarpy of many Malvales and Geraniales is distinctly in- 

 complete, the coherence between the carpels being so feeble 

 that they readily separate at maturity. All told, fully 10,000 

 species of this class are passed before complete syncarpy is 

 attained. 



The strobiloid flower structure, in which the axis is elong- 

 ated, cylindrical, spheroidal, or flattened, bearing on its sur- 



