188 Trans. Acad. Set. of St. Louis. 



and short-styled flowers are mentioned and characterizes the 

 short-styled forms as male in function since as they are vis- 

 ited exclusively by pollen-collecting bees there is no way in 

 which pollen can be transferred to the stigma. In comment- 

 ing on the letter Darwin correctly interprets them as cases of 

 polygamy through abortion rather than truly heterostyled 

 forms . 



Early in the summer of 1902, I noticed that there occurred 

 in many of the flowers of S. CaroUnense L. a strong reduc- 

 tion in the size of the pistil, and concluded that some idea of 

 the frequency of the occurrence might be of interest from a 

 biological, and possibly from a taxonomic, standpoint. 



While all the literature of S. Carolineyise has not been 

 examined the most important has been consulted. The only 

 reference to the sterile flowers seems to be that of Sendtner, 

 who says of this species: *'Flores vidi nonnisi steriles absque 

 pistillo." The pistil shows considerable range inform, being 

 sometimes exserted for perhaps as much as two-thirds the 

 length of the anthers, while again the capitate green 

 stigma extends only to the end of the anthers, or a less dis- 

 tance. Dunal, in the Prodromus, says: "Stylus * * * 

 rectus et staminibus longior vel apice recurvatus et stamin- 

 ibus brevior," which appears to be due to lack of material, 

 for in a very large per cent, of the exserted styles examined 

 there is a more or less strong curvature, while in those of the 

 length of the stamens or less, it is either straight or curved. 

 In the sterile form the pistil is simply reduced in size, having 

 about the same length as the filaments. Sometimes the 

 stigma has assumed the characteristic green coloration, and 

 sometimes not. The form of the pistil in the mature sterile 

 flower corresponds to that of the pistil in the young bud of 

 the perfect flower. The development of the stamens is at 

 first more rapid than that of the pistil. 



While I have not now before me such a series of material, 

 I feel confident that in the material examined there was a 

 complete series of mature flowers extending from the longest- 

 styled forms to those in which the pistil is most reduced. 

 At the same time, transition stages are rare, the reduction, 

 where it occurs, being usually very pronounced. 



