the link below states a difference as:
Lupinus perennis "Leaves are divided into 7 to 11 leaflets"
and
"A similar species in Minnesota is Large-leaved Lupine (Lupinus polyphyllus), a non-native introduced by gardeners which has become invasive especially along the north shore of Lake Superior. It is overall a larger plant with taller spikes and 9 to 17 leaflets."

eta:
it is my understanding that there can easily be cross-breeding as well.

Here is a link that might be useful: minn. wildflowers - wild lupine

This post was edited by bubbleoffplumb on Wed, Jun 25, 14 at 11:54

Lupinus perennis. I have several on my property and the photo of your plant is a carbon copy of my plants.

Awesome! That's great to know- thank you both so much for your help! I think these might be Lupinus Polyphyllus, because the stalks were well over 2 feet in height.

This post was edited by Lealam on Thu, Jun 26, 14 at 1:25