YIKES...better get it out quick, thanks

Maybe I'll try that with my bush cherries too. I haven't planted anything under them except for daffodils because I wanted easy access for picking without worrying about stepping on plants but I may try flowers on one side and leave open access on the back side.

There are many species of Epilobium, some of which have had name changes, like the fireweed. Some are native, some are introduced weeds. There's only one fireweed though, by whatever name. Watson's willowherb is a common garden weed, I think it's Epilobium ciliatum now, used to be Epilobium watsonii. Dry or damp, sun or shade, tall and rank or short and sparse. Seeds, no runners. The one in your garden is probably the Watson's although you may also have others like Epilobium minutum in dry spots. I'm sure bboy is much more knowledgeable about the various species than I am, I usually do well enough just going by 'Epilobium species'. What you have in the photos on the Weeds forum sure look like Watson's willowherb gone to seed. They've done really well this year with the cool damp spring. But the photos do need to be larger to really see. I'm just guessing from the silhouette.

"If the OP wants a ground cover and has space I can't see much objection to it" No doubt. And agree they are very pretty, just not the kind of team player I cultivate and I get my fill of them driving by uncultivated areas. The OP says "in my garden..." As far as opinions go, all of the plants in the pics (except the bulb that belongs to the long blades in the 2nd pic) would be composted @ my house... as I obtain/propagate other plants to take the space.