1 882.] The Heterogony of Oxalis violacea. 1 3 



THE HETEROGONY OF OXALIS VIOLACEA. 



BY WILLIAM TRELEASE. 



IN May of the present year, after collecting specimens of the 

 violet wood-sorrel about Madison, Wis., I noticed that I had 

 succeeded in getting two well-marked forms of flowers, in one of 

 which the pistils were considerably longer than the stamens, 

 which were in two sets of slightly different length, while in the 

 other the pistils were shorter than either set of stamens. On the 

 supposition that these were respectively the long-styled and 

 short-styled forms of a trimorphic species, careful search was 

 made for the mid-styled form. In a class exercise in analysis, 

 something over one hundred plants were studied, but only the 

 two forms above mentioned were found, and in nearly equal num- 



o 



Fig. 1 .—Long-styled flower of Oxalis violacea. I 

 the same species. Magnified eight diameters. 



bers. An examination, made by myself, of the flowers of about 

 a hundred additional plants, from different localities within an 

 area of a few miles, gave a similar result. 



Up to this time no accurate record of the number of plants of 

 either form, or of the absolute lengths of stamens and pistils had 

 been made, attention having been given only to the presence or 

 absence of mid-styled flowers, and, in a general way, to the relative 

 abundance of the two forms which were found. Alter this eighty- 

 one flowers, gathered at random from as many plants, were care- 

 fully examined, and it was found that in fifty-one the styles were 

 nearly twice as long as the average of both sets of stamens, 

 while the styles of the remaining thirty were shorter than either 



