18 



BURS A BURSA-PASTORIS AND BURS A HEEGERI : 



of my cultures. Few showed even a suggestion of the squarish lobes 

 which were so conspicuous in the parent, thus indicating- that the strong 

 development of that characteristic in the parent was in all probability 

 merely a fluctuation. These plants differed from those considered typical 

 of B, bp. heteris in having the primary lobes of the climax-leaves oblong 

 and blunt, not attenuate. However, in some specimens the later leaves 

 showed the attenuate lobes of typical B. bp. heteris, and this fact leaves 

 little doubt that another generation would have completely demonstrated 

 that this family belongs to B. bp. heteris. 



Whether a culture (0645) produced from seeds sent by Dr. D. T. Mac- 

 Dougal, from Tucson, Arizona, is likewise identical with the B. bp. heteris 

 grown from seeds collected in Illinois, Ohio, and Long Island, has not 

 been sufficiently tested. While the Tucson plants had in a most strongly 



marked way the primary and secondary lobes 

 described above, there were striking differences 

 in the texture and color of the leaves, the form 

 of the lobes, and the form, size, and texture of 

 the stem-leaves or bracts (fig. 8). As only one 

 generation of plants has been grown from these 

 seeds, no proper grounds exist for attempting 

 to decide as to the permanence of the differences 

 exhibited, but it might be expected that plants 

 from the hot, dry, intensely lighted plains of 

 Arizona would display considerable changes of 

 a purely transitory nature on being transferred 

 to the moist atmosphere and relatively dim light 



of a more northern propagating-house. 

 PIG. 1. Bursa bursa-fiastons , 



heteris. Climax leaves of a Field observation indicates that the type of 



specimen growing near Cold rosette possessed by Burs a at Tucson, of which 

 Spring Harbor, Long Island. . . ... <i - ^ 



this culture was a fair example, is the common 



type if not the only type of rosette displayed by Bursa in that locality and 

 westward. Many facts now at hand suggest that the heteris type is the prim- 

 itive type of rosette from which the forms to be described below have been 

 derived, and the relatively wide geographical distribution of this type is 

 in strong support of this view. 



Bursa bursa-pastoris tenuis n. sp. element. 



This differs from the preceding type in several important features. The 

 sinuses are relatively shallow, rarely extending nearly to the midrib in 

 very strongly developed individuals. The terminal lobe is not separated 

 from the nearest lateral lobes by deep, clean-cut sinuses, but these more 

 distal sinuses are relatively shallow, so that one can with but scant pro- 

 priety speak of the terminal lobe as a definite morphological structure; 



