Coreopsis lanceolata: flower

Coreopsis lanceolata, known in English as lanceleaf coreopsis or lanceleaf tickseed and in French as coréopsis lancéolé or œil de jeune fille is a perennial native to much of North America. The bright yellow daisy-like flowers have wide petals with scalloped edges.

Coreopsis is happiest in the sun; my plant (which I bought at the Toronto Botanical Garden's spring plant sale) struggled in what I had thought was a "partial shade" location. Deadheading will result in more blooms.