The names “delphinium” and “larkspur” are not interchangeable, as they refer to two different plant types. Historically, they were used homogeneously, but within horticultural science and industry, we’ve moved away from that usage. Delphinium refers to flowers in the Delphinium genus (e.g., D. elatum, D. grandiflorum, etc.), which can be grown as perennials. Larkspur, on the other hand, refers to flowers in the Consolida genus (e.g., C. ajacis, etc.), which are typically grown as annuals.