Black-Eyed Susans, flowers

Butterflies flock to this North American flowering plant—specifically to their dark center, which contains about 200-300 small tubular-shaped flowers. For these critters, this acts as a shallow cup of nectar, MacLean says. "They prefer full sun, well-drained and fertile soil, and are best used as a backdrop to any pollinator garden, as they can get up to 3 feet tall."