Hi I saw American vetch on the side of the road this evening and on the other side I saw a plant that looked very similar to it so I gathered a bunch to identify and it turned out to be purple crown vetch. Do you know why they look so similar and yet one is native and one introduced? I spotted it in white bear lake by bald eagle lake.

There are a lot of plants that look similar to MN native plants, but are not native. In the case of crown vetch, as I understand it, it was actually engineered, intended to be used for erosion control. It got out of control instead and has become an invasive species.

BTW, unless it's your own property I recommend you take pictures of wildflowers you want to identify later, rather than pick them. You don't know if you're taking something harmful, or causing harm to the habitat. Besides, you could be fined if you're caught taking flowers from public lands.

Masses of these in several open areas of Oakdale Nature Preserve, often intermixed (but generally out-competing) Bird's-Foot Trefoil.

I found one of these with opposite and alternate leaves, does that make it a mutant plant?

There are sometimes unusual variations in species that don't necessarily mean a genetic mutation. Also, if alternate leaves are very close together they might look opposite. And keep in mind that for a species with compound leaves like crown vetch, the attachment doesn't refer to the leaflets, but the entire compound leaf.

These are growing in a few places on the backside of the college. I also have some growing in my backyard garden.