What is the perennial called which is very very thin and tall and has a purple bloom at the top?

I have planted this this past week and didnt look to see the name of it?





anyone can guess?





also how long generally does it bloom for ?








Thanks for your answers!What is the perennial called which is very very thin and tall and has a purple bloom at the top?
Verbena bonariensis.


It has a very long blooming period of about two months.





http://images.google.com/imgres?imgurl=h鈥?/a>What is the perennial called which is very very thin and tall and has a purple bloom at the top?
The only thing it sounds like to me is liatra. Do a Google search on ';liatra picture'; and see if it is what you have and please give me a ';best answer'; if I am right!!! :o) The blooms last quite a long time as they bloom from the top down.
verbena bonarensis.flowers til end oct.will self seed if good soil