Where is it growing stone?
By knowing which area it is in the following site shows which species are growing in that area, there are some photos and line drawings which help but it's a good idea to google for reliable sites to compare.
http://luirig.altervista.org/f...
If you scroll to the bottom of the link there are some photos and line drawings, the leaf looks to match that of Eupatorium fistulosum.
E. fistulosum isn't in the list, but is a synonym of Eutrochium fistulosum ..
http://www.theplantlist.org/tp...
http://plants.usda.gov/core/pr...
http://plants.usda.gov/core/pr...
Leave: "margins finely serrate (teeth rounded, blunt)"
http://www.efloras.org/florata...
