In article , griffon wrote:

A friend had a weed/volunteer plant in her flower beds last year and
it is starting to come back up and she says it appears to have spread
out somewhat and is shooting up around the place where it was last
year. She says the plant actually looks similar to some kind of phlox
or loosestrife, particularly the latter in the blooms. The blooms are
smaller than those of yellow loosestrife and there are not very many
blooms either. That is about all she can tell me. I have no ideas
but if anyone has suggestions, I will send them to her and maybe she
can identify it. Thanks.

Well, loosestrife is certainly invasive & spreads in just that manner.

-paghat

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
See the Garden of Paghat the Ratgirl: http://www.paghat.com/