What is this plant called?

My wife asked me to post a couple of pictures of a flower in one of her flower beds that she doesn't recognize. If anyone here can tell us what it is, we would be grateful indeed.

 

it reminds me of a perennial lobelia.

 

Hi redhawk44,..i am inclined to agree with Carolyn about this being a Lobelia,..i am sure its,.. Lobelia 'Great Blue'.

 

Thanks to both of you, I will show her this.

 

Agreed ... Great Blue Lobelia. It is native to eastern and central Canada and United States.

 

Texas blue bonnet.

 

Hi all, I am currently growing the perennial lobelia. It is a lovely plant: beautiful blue flowers at an unusual time of the year for blue (late summer, early fall). The leaves are attractive. Flowers contrast well with all the yellow bloomers this time of year.

Good luck redhawk44 with your lovely plsnt.

 

I wouldn't try to attach a cultivar name but it looks like Lobelia siphilitica.
http://www.gardenstew.com/plantstew/34531

 

I agree Purple. The lobelia that I have grows less densely. It is in slightly less than full shade.