The photo of larkspur flowers above shows a purple colored variety.
The genus of larkspur is Delphinium, same as the perennial that goes by that name (in fact, some people use the words interchangeably). The name, "delphinium" has a rather unlikely derivation. It goes back to the Greek word for "dolphin," due to the flower shape in some species.
I grew purple larkspur flowers in a container garden last year and was quite happy with the extra color they provided for my landscape. What made me even happier, perhaps, is the fact that my purple larkspur flowers re-seeded, meaning I'll be able to enjoy free blossoms this year!