Tall Thistle (Cirsium altissimum) is not one of my favorite flowers, but I let it grow in my prairie meadow because it's such a magnet for butterflies.  Here a Gulf Fritillary  enjoys its nectar. This butterfly is a bit of an enigma.  It looks like our true fritillaries, but some lepidopterists think it is more closely related to a tropical group, the Helicon butterflies.