42 



fertile plants propagating and spreading themselves by means of 

 seed. And thus would arise a race of plants with a stable heredity — 

 and in this instance a race so different from the ancestral Linaria 

 that any taxonomist seeing it for the first time would place it in the 

 Scrophulariaceae, but would be completely justified in describing 

 the group as a nezv genus. 



While on this topic of the possible origin of taxonomic units 

 above those of species, one cannot help but point out the structural 

 similarity of the flowers of this unusual form of Linaria (as shown 

 by Figures 16a-c) and that of the common Culver's root, Veroni- 

 castrum virginicum (Figures 17a-b). Although members of the 

 same family, it is not implied that these two plants are of imme- 

 diately mutual derivation. It is suggested only that the reduced con- 

 dition of the nearly regular flowers of Veronicastrum (occurring 

 as it does in a family with so much zygomorphy) may have been 

 derived in a manner somewhat similar to the reduced and nearly 

 regular forms of Linaria vulgaris with, of course, the advent of 

 fertility due, possibly, to polyploidy of one sort or another. The 

 possibility that Veronicastrum may be an anomalous genus the 

 result of convergent evolution and is placed in the Veroniceae solely 

 on the basis of its flower structure — with but little regard for the 

 whorled condition of its leaves— must not be excluded from any 

 ultimate discussion of the phylogeny of the group. It is our opinion 

 that Veronicastrum is not necessarily a primitive member of this 

 tribe as Pennell^ has suggested. 



For some years the study of "abnormal" flowers has been 

 frowned upon by the systematist, but it is our opinion that if these 

 forms are examined more closely in the future they will shed con- 

 siderable light on the mechanics of the origin of the larger taxo- 

 nomic units, such as genera and even families. This will be true 

 particularly if these abnormalities are looked upon not merely as 

 vegetable curiosities, but are studied both from the anatomical and 

 cytological standpoint. 



The New York Botanical Garden, 

 New York, N. Y. 



^ Pennell, F. W., "Veronica" in North and South America. Rhodora 

 23:1-41. 1921. The Scrophulariaceae of eastern temperate North America 

 Phil. Acad. Nat. Sci. Monog. No. 1. 1935. 



