PLANT TAXONOMY IN AN AGE OF EXPERIMENT 587 



characters are combined, separated, and recombined in nature and how new 

 types of individuals and populations may arise. Artilicial production of poly- 

 ploids has given us clues as to the nature and origin of polyploid systems in 

 nature, although their present genetical behavior may be very different from 

 what we must assume it once to have been. We can no longer escape the con- 

 clusion that hybridization is rife under at least semi-natural conditions and 

 that it must be reckoned with seriously by the systematist. At the lower 

 taxonomic levels we can obtain invaluable evidence from genetics and cytology 

 to correct, supplement, or even replace our tentative conclusions from other 

 kinds of observation. 



It remains that genetical evidence is one more kind of evidence, that it has 

 no unique monopoly on Truth, and that a system of classification built on 

 genetical data alone is artificial and special and lacks general utility. Neverthe- 

 less, the taxonomist cannot afford to omit genetical tools and viewpoints from 

 his professional equipment. 



Turesson's neglected term "genecology" seems to me the preferable one 

 to designate the observation and comparison of the behavior of organisms of 

 known cytogenetical constitution under identical or contrasted environments. 

 Its basic accomplishments have been to show that physiological capacity is 

 inherited just like other features of the individual, and thus to provide an- 

 other set of characters for taxonomic evaluation. We have gained a fascinating 

 new vista of the biological complexity and geobotanical fractioning of natural 

 populations under field conditions. I am inclined to think, however, that the 

 attempt to equate genecological categories with taxonomic ones, or to sub- 

 stitute the former for the latter, was overhasty and ill-advised. Each has 

 validity within its own frame of reference and very little outside it. The 

 taxonomic system is best employed as a repository for the totality of all kinds 

 of evidence and should recognize no favored kinds of truth. Certainly, our 

 appreciation of the intricacies of relationship among individuals of a popula- 

 tion has been wonderfully enhanced by the endeavors of Turesson and 

 Clausen, Keck, and Hiesey and their disciples, and much remains to be done. 



The application of biochemical data to the taxonomy of vascular plants is 

 perhaps the next great advance to be anticipated. Very little of unquestion- 

 able merit and applicability has been done thus far; much may lie ahead. 

 Most of us speak hopefully but vaguely of serum diagnosis, but few seem to 

 have explored the abundant German literature on the subject to assure them- 

 selves of the scientific objectivity of its embattled "schools." It is gratifying 

 to note that this field has recently shown signs of rejuvenation along sounder 

 lines. Botanists have long been aware of the presence of characteristic colors, 

 odors, tastes, essential oils, latex, alkaloids, glandular exudations, and the 

 like, in setting up empirical relationships. It is only logical to assume that 

 these features have an ascertainable and classifiable biochemical basis. At- 

 tempts to establish classification on such features in higher plants have been 



