588 CONSTANCE 



few and can be as yet of little more than prophetic interest. We may have to 

 await the establishment of adequate classifications of biochemical substances 

 and processes before we can hope to utilize them freely in systematic botany, 

 but we should not forget their great potentialities. 



In terms of formal schematization, the device by which taxonomists attempt 

 to record their over-all advances and mark the ground gained, the past fifty 

 years have seen the complete recasting of the organization of the vascular 

 cryptogams, with the breaking up of the "Pteridophyta" into smaller and 

 more unified groupings on the basis of paleobotanical, morphological, ana- 

 tomical, and embryological evidence. The gymnosperms have been and are 

 being drastically re-evaluated and reorganized as their extinct members have 

 come under intensive scrutiny, their embryology has been re-examined, and 

 they have been studied extensively in the field, by such workers as Buchholz, 

 Sahni, and Florin. 



Proposed classifications of angiosperms, however, have been scarcely revolu- 

 tionary during this period. Rendle, Wettstein, Janchen, Pulle, Skottsberg, and 

 Lam have pursued elaboration and modification, on various grounds, of the 

 basic Englerian sequence. Bessey, in 1915, re-enunciated his earlier-proposed 

 arrangement along Candollean-Bentham and Hooker lines; Hallier and Lotsy 

 and Gunderson, to name a few, have expressed varying but rather similar 

 ideas. Hutchinson has produced a new and ostensibly phylogenetic classifica- 

 tion after the Bentham and Hooker model, but notable for the subdivision 

 of dicotyledons into woody versus herbaceous phyla, the large number of small 

 orders, and a complete and useful reorganization of monocotyledons. Hayata, 

 for one, has framed an arrangement for flowering plants that is founded on 

 abandonment of the hope that there is any one phylogenetic solution to the 

 mysteries of angiosperm evolution. Others have scoffed at the ideal of a phylo- 

 genetic classification, in favor of some kind of utilitarian device. It seems 

 clear that no system constructed in the past half century has fully capitalized 

 on the accumulations of data referred to above. It is encouraging to note that 

 papers given at these meetings are attempting to remedy this lack. However, 

 there seems to be rather general agreement that sufficient evidence to formulate 

 a really new, thoroughgoing, and generally satisfactory phylogenetic arrange- 

 ment of flowering plants is not yet available. 



In summary, systematic botany is healthy but in a state of profound transi- 

 tion. Significant new textbooks, those of Lawrence (1951, 1955) and Core 

 (1955), are attempting to broaden the subject of plant taxonomy at the 

 undergraduate level and to show that it can be more than concern with a 

 limited local flora, the mechanics of nomenclature, and dry and formal 

 terminology. The past fifty years have seen substantial accretions of data of 

 taxonomic significance from all the older sources of such evidence and from 

 quite new sources. We may confidently expect that information will continue 

 to flow in at an ever-increasing tempo, and we should be prepared to receive 



