I've not observed stolons in Dieciocho de Marzo, but have often seen them in La Trinidad Pink and some greggiis and x jamensis forms.

It is probably just a layered stem that I forgot about then. It is only my second year with La Trinidad Pink and I'm definitely seeing stolons on that one. Hopefully they will come out of the ground OK because the plant needs to be moved. I figure I'll dig a big root ball and then shake off the soil to see what is there. Presumably it is dividable.

This year I need to be more proactive about layering the sages - all the bush sages. Over the years I've grown them it was often only the layered branches that survived the winter.

That is how they persist in nature as well.