44 



confined to only a few plants. He makes the suggestion that it 

 would be desirable to examine more extensive collections to see 

 If stamen dimorphism is characteristic of the species and accord- 

 ingly the writer made it a point to look over the specimens of 

 it in the herbarium of the University of Minnesota to see if ad- 

 ditional proof could be obtained. The observations on the 

 herbarium material were supplemented by a study of numerous 

 specimens in the field in May, 191 8. 



These observations show beyond any doubt that the stamens 

 of Erythronium propuUans, like those of several other species of 

 the genus, are characteristically heteromorphic. In fact there Is 

 perhaps an even greater proportional difference in the lengths of 

 the two sets of stamens than is found In the other species, for in 

 E. propuUans the outer whorl of stamens reaches scarcely above 

 the base of the anthers of the inner set. The accompanying 

 stereoscopic photographs, which were made with a Zeiss stereo- 

 scopic camera with regular binocular objectives and with the 

 flowers. Immersed in water, show this fact clearly. (The value of 

 the figures is enhanced by examining them through an ordinary 

 stereoscope.) 



In the field material the average length of the outer stamens 

 Is 6.32 mm. while that of the Inner is 7.99 mm., a difference of 

 1.67 mm. There Is considerable variation in the size of the 

 anthers ranging from 1.9 mm. to 3.5 mm. in length. The aver- 

 age length is about 2.46 mm. In some flowers the anthers of 

 the outer stamens are regularly about .5 mm. shorter than those 

 of the inner but this is not generally the rule and many cases 

 were noted In which the anthers of the inner stamens were smaller 

 in size than the outer. For the most part the anthers of one 

 whorl of stamens differ as much from one another in size as they 

 differ from those of the alternating whorl. This marked ten- 

 dency to variation in the length of the anthers does not seem to 

 affect the filaments for in all flowers examined the outer filaments 

 were found to be constantly and uniformly shorter than the inner 

 ones. 



While examining the flowers for stamen heteromorphism an- 

 other feature was brought to light which apparently has hitherto 



