2Q2 BOTANICAL GAZETTE. [ August 



Notes upon Lithospermum.— The Hoary puccoon {Lithospermum can- 

 escens Lehm.) is a common prairie plant of high ground, flowering con- 

 spicuously in the month of May. This species is decidedly dimorphic, as 

 has been previously observed by Dr. Bessey, and may be occasionally tri- 

 morphic, as reported by Mr. Smith, of Michigan. I have seen no indica- 

 tions of this last condition. 



The styles of the long-styled flowers are from 6 to 11 mm., averaging 

 7.7 mm. Stamens in the same flowers are 3 to 4 mm., averaging 3.4 mm. 

 above the receptacle. In the short-styled flowers the styles are 2 to 4 mm., 

 averaging 2.9 mm. ; and the stamens 7 to 8 mm., averaging 7.6 mm. The 

 long or high stamens have short filaments } to \ mm. long, attaching the 

 anther to the corolla tube, while the short or low stamens are practically 



sessile. 



It is, however, to the pollen of this plant that attention is called. 

 That of the high stamens ranges from 11-13 by 22-25/x, with an average 

 of 12 by 24//, That of the short stamens varies frem 7-10 by 15-21/*, and 

 averaging 8 by 17.5/*, or about two- thirds of the diameter of that of the high 



stamens. 



The measurement* are not easily taken owing to the peculiar shape 

 of the grains, which consist of two large portions connected by an isth- 

 mus, the whole being somewhat dumb-bell shaped, with one end larger 

 than the other. In fact the outlines made upon white paper by using the 

 camera might be easily mistaken for representations of boot tracks in the 



snow. 



Upon making comparative tests for germinative power, it was found 

 that after a given period in sugar solution about one in fifty of the short- 

 stamen grains had pushed out tubes of a length not exceeding the longer 

 diameter of the grain. During the same time, twice as many of the 

 larger grains produced tubes some of which were ten times the longer 

 diameter of the pollen. 



The tubes of the pollen from the high anthers need to grow through 

 a longer distance of style and this may be sufficient reason for the greater 

 vigor of each germinating grain, but the reason for the larger percentage 

 of tube-producing grains may not be so apparent. It may be true that 

 the difference in size in grains might render the same strength of sugar 

 solution unequally favorable for growth. 



Turning to the stigmas, there is a corresponding difference between 

 those of the two lengths of styles. That of the long styles is 25 per cent, 

 larger than of the short, and the papillae of its surface are about twice as 

 long. 



Considerable attention was given to a corresponding study of another 

 prairie puccoon, namely, Lithospermum angustifolium. I was not able 

 to satisfy myself that the latter is distinctly dimorphic. There was a 

 great variation in the lengths of the styles and stamens, but the age of 

 the flower seemed to have much to do with this. The tube of the corolla 

 elongates rapidly at the time when the lobes are spreading and the 



