144 CRUCIFER/E. 



tains a single European and North Asiatic species (T. glabra, Linn.), which 

 is also found in the northern parts of this country, to which several, chiefly 

 more boreal, American species have recently been added. It should, 

 perhaps, form only a section of Arabis, and comprise A. Canadensis, A. lae- 

 vigata, and A. pendula. 



PLATE 59. Turritis stricta, Graham; — summit of a flowering, and 

 of a fruit-bearing stem ; of the natural size ; from Watertown, 

 New York. 

 1. A sepal ; and 2, a petal; enlarged. 



3. Pistil, magnified ; the base cut away ; showing the two ranks of ovules 



in each cell. 



4. Silique transversely divided below, magnified, showing the two ranks 



of seeds in each cell. 



5. Replum from the upper end of a silique, with the seeds in place ; mag- 



nified. 



6. Tissue from the partition, highly magnified. 



7. Magnified seed, divided transversely. 



