82 THE AMERICAN BOTANIST 



family in North America in which the disk-flowers are two- 

 Hpped or bilabiate as the botanist has it, like the flowers of 

 sage or snapdragon. Under the lens the tiny flowers are seen 

 to have a three-lobed lip on the side toward the exterior of 

 the flower-head and a two-lobed lip toward the center. The 

 ray-flowers are usually white but sometimes they are tipped 

 with red giving the flower-head somewhat the appearance of 

 the English daisy. In books wdiose nomenclature follows the 

 "American" Code the plant is called Thyntsanthema semi- 

 floscnlarc. That spring had reached North Carolina by the 

 middle of March was attested by specimens of this plant in 

 bloom sent by H. A. Rankin of Hallsboro. 



Changing the Sex of Plants. — The majority of plants 

 have stamens and carpels in the same flower but a good many 

 others vary this arrangement. In some cases the stamens and 

 carpels are on separate plants as in the willow and Cottonwood ; 

 in others they are on different parts of the same plant as in 

 the pines and maize. In the group of which the Jack-in-the- 

 pulpit or Indian turnip (Arisaema triphyllum) belongs, some 

 plants bear only carpels, some bear stamens, and some a mix- 

 ture of the two. This condition suggests that the sex of such 

 plants is not so rigidly fixed as it seems to be in other plants 

 and might not be incapable of change. Among some of the 

 lower plants, sex often appears to be determined by the food 

 supply. In some of the ferns the prothallia grown on sterile 

 media may produce nothing but sperms similar to the pollen 

 elements, while an abundance of food results in archegonia 

 containing eggs such as are found in the carpels. A similar 

 conditions exists in the gametophytes of Bqiiisehirn and Selag- 

 iiiella. In the American Journal of Botany for February, 

 Dr. J. H. Schaffner records his experiments with the Indian 

 turnip and its ally the green dragon (A. dracontiitni) in try- 



