Quote by Thoreau

[Adolf Ceska]

In a previous article, Robert_Lebowitz at Mankato.MSUS.EDU 
(Robert J. Lebowitz) says:

>I am trying to track down a quote which one of my colleagues has attributed to 
>Thoreau... "A weed is a plant whose virtue is as yet unknown."  Can anyone 
>cite the source and correct author of this quote???

Ralph Waldo Emerson (1803-1882):
"What is a weed? A plant whose virtues have not been discovered."