TO 



JOHN TORREY, LL. 



CORRESP. MEMBER OF THE LINN.EAN SOCIETY. ETC.. 



THIS VOLUME IS DEDICATED, 



IN GRATEFUL ACKNOWLEDGMENT 



OF THE FRIENDSHIP WHICH HAS HONORED AND THE COUNSEL 

 WHICH HAS AIDED 



THE AUTHOR 



FROM THE COMMENCEMENT OF HIS BOTANICAL PURSUITS. 



CAMBRIDGE, January 1, 1848. 



