PLANT TAXONOMY IN AN AGE OF EXPERIMENT 583 



nearly continuous attack for several decades by students of ontogeny, physi- 

 ology, paleobotany, and evolution, shaking the whole tenuous framework of 

 systematics. If I read the record correctly, however, pre-evolutionary morphol- 

 ogy has proved to be rather more durable and resilient than might have been 

 anticipated and modification rather than abandonment of the bases of our 

 laboriously contrived classifications seems to be called for. Telomic and 

 cauline floral organs and stachysporic sporangia appear to be concepts of 

 doubtful validity, at least in the angiosperms, and are certainly of less use to 

 us than the more conservative interpretation of floral structures as basically 

 foliar. The frequent association of primitively simple secondary xylem with 

 sporophyll-like carpels and sporophyll-like stamens appears to have been 

 firmly established. 



We might regard as special branches of morphology other sources which 

 have furnished data of taxonomic utility, notably descriptive anatomy, 

 embryology, and cytology and paleobotany. 



Anatomy, the first of these in time, beginning with the work of Malpighi 

 and Grew in the 17th Century, advanced rapidly and had assembled a well- 

 organized body of systematic data by the end of the 19th Century. The uses 

 of systematic anatomy by such workers as Radkofer and Van Tieghem in 

 the past century are too well known and appreciated to require emphasis. The 

 authors of Die Pflanzenfamilien were perhaps the first to apply anatomical 

 characteristics to over-all classification on the grand scale. In this country, 

 the contributions of Jeffrey and his distinguished students — Bailey, Eames, 

 and Sinnott — and their students, and their students' students, to systematic 

 anatomy are of conspicuous importance. It would perhaps not be an exaggera- 

 tion to state that the pattern has been laid for an over-all classification of 

 vascular plants on morphological-anatomical grounds that may ultimately 

 replace all prior ones. At the same time we should not forget that even the 

 rich treasuries of anatomical information, represented by the masterly compi- 

 lations of Solereder and Metcalfe and Chalk, deal mostly with selected plant 

 structures and that a very large number of plants are not represented either 

 in whole or in part. 



The findings of Irving Bailey and his associates with regard to the develop- 

 ment, form, and sequence of vessels and vessel types in vascular plants have 

 shed a clear, cold light on the relationships of gymnosperms with angiosperms 

 and of monocotyledons with dicotyledons. The analysis of floral vasculariza- 

 tion by Eames and his students has done much to unravel the trends and 

 permutations of floral evolution and to enable us to discriminate between 

 primitively simple and secondarily simplified modes of organization. By 

 application of such information, the so-called "Amentiferae" have been 

 neatly deprived at once of both their supposed unity and the basal position 

 among dicotyledons accorded them by Engler, Rendle, and Wettstein. 

 Cheadle's application of similar criteria to monocotyledons indicates the 



