I don't think so. Ageratum is a composite with no possibility to hybridize with a Salvia (mint family). By white sage, do you mean sagebrush, which is an Artemisia, and a composite"

I'm really not sure....I decided to include some pics..maybe someone can identify them for me.
This 1st group is the plant in question...it has many flower 'clusters' at the top and is about 4 ft tall:
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This next two is what I think is actually an Ageratum..there is only one 'cluster' of flowers at the top and it is about 2-2 1/2 ft tall. The leaves are not as long or as narrow. Are they the same????
{{gwi:1245799}} {{gwi:1245800}}
Thanks for any info on ID
Linda

Hi,
It is Eupatorium perfoliatum(Boneset.)
Remy