Keep in mind with Golden Alexanders, its definitely best to get seeds or plants from a nursery, unless you know how to positively ID it. Mistakenly collecting Wild Parsnip seeds would be an awful mistake! The Eastern Tiger Swallowtail caterpillar uses the Tulip tree, as well as other trees. Last year I began adding a bunch of Common Blue Violets and Confederate Violets in hopes of attracting fritillary butterflies. Hopefully after a year or two they'll fill in and that'll happen. Great spangled fritillary butterflies are one of my favorite butterflies.