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One of the best reference works on trees and shrubs for British gardens – and the whole text free on the Internet! Hats off to the International Dendrological Society.
Diigo links for 12/17/2014
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State and Federal Noxious Weeds List | USDA PLANTS
Handy list of noxious weeds in the US – essentially, if it is listed here, forget trying to commercialise it in the US.