extinct species

[Anita F. Cholewa]

Can anyone give me some examples of vascular plants that are known to have gone extinct in the continental US/Can since colonial times?  (Not counting Franklinia).

thanks

________________________
Anita F. Cholewa, Ph.D.
Curator of Temperate Plants
Bell Museum of Natural History
University of Minnesota
1445 Gortner Ave
St Paul MN (USA)
http://www.cbs.umn.edu/herbarium/vascularplantpage.htm