Single bloom geranium
The petals are streaked with darker lines along the length, and often fade to white at the base.The 5 green sepals behind the flower are about half as long as the petals, and hairy.Hardy geraniums can live through frost while pelargoniums cannot.
Invasive might be a good word to use, but if not, they do spread fast. They tend to stay out of my lawn, so I don't worry about them because they are a very pretty light purple bloom against all green background. I have even transplanted some of them to form a bed along a brick paver walk.
I have some growing in my own yard and it has not spread hardly at all in 4 years.
Regardless, when a species finds suitable habitat without much competition it is likely to perform better than in less ideal conditions.
It can be confusing at times when it seems that only horticulture called them by their true name.
Most of the plants we grow are Pelargonium, not true geraniums.
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Some hardy geraniums will even experience a second bloom.