Lalics in Montana

Spending summer in NW Montana and have been looking at all the Lilacs here. Asked a few people the names of some but so far no one know for sure the name of the different types. Would like to take a couple back to Missouri and see how they will do. Looking for the type that is a dark purple and one of the white species.
Any suggestion would be helpful.

Most of the Lilacs out west were the type available to the early settlers, "old fashioned lilacs" , the unnamed basic species. Dark purple might be a natural variation but white would probably be named variety - there are some old "antique" varieties of white lilac. Try taking a photo and posting it to the plant ID forum (there doesn't seem to be much activity on the Rocky Mountain Gardening forum these days). If you are researching on the internet, try Syringa, the botanical name. The other thing you ought to do is just go into a local nursery - in Montana & in Missouri - and ask. Most will grow in zone 7 in slightly alkaline soil, so probably do okay in Missouri.