6 Rhodora [January 



HYBRIDISM IN THE GENUS VIOLA — IL 

 Ezra Brainerd. 



The discussion of this subject, coimnenced over a year ago/ I 

 purpose to resume in this and a subsequent paper. During the past 

 year the problem has been studied persistently; most of the known 

 aberrant forms of northeastern America have been grown in tlie gar- 

 den; and several journeys through the coastal region of the Middle 

 and New^ England States have been made to observe anomalous plants 

 in their natural surroundings. I take pleasure in saying that in all 

 this investigation I have been greatly assisted by the kindness of 

 numerous students of the gemis, who have .sent me living plants and 

 herbarium specimens, and have seemed to spare no pains to guide 

 me to stations of special interest. 



The result of these observations is to confirm in every particular 

 the inferences of my previous article, and, furthermore, to bring to 

 light .some twenty-five additional liybrids and cro.sses in the genus 

 Viola. In short, as regards at least the blue acaulescent violets of 

 northeastern America the general rule seems to be inductively estab- 

 lished, that of the current]}/ recognized species any two, that have been 

 (jroioing together for several years, are likely to present hytrrids. 



Before entering upon the details of this evidence, certain prelim- 

 inary matters should be presented, as helpful to a better understanding 

 of the problem. 



IIVBHIDISM AMONG EUROPEAN ViOI.ETS. 



It is interesting to note that in recent years a similar tendency to 

 interbreed has been recognized in the European species of Viola. In 

 the last edition of Garcke's Plora of Germany eighteen violet hybrids 

 are reported as having been found among their twenty species. In 

 a list of the plants of Norway and Sweden published in 1900 twenty- 

 two violet hybritls arc enumerated among their twenty-seven species. 

 In a recent number of the Botanische Zeit.schrift Dr. Ileinrich Sabran- 

 sky gives a list of ten species and nine hybrids that he has found in a 



1 RuoDOHA, vi. 213-223, Nov., 1904. 



