One of the species I was hoping to see in California or Oregon last month was this one, Delphinium nudicaule, commonly known as red larkspur, scarlet larkspur or canyon delphinium. As you may note from the second photograph, it is a species of rocky soils; the Flora of North America reports it is only found in moist talus or cliff faces (but at a wide range of elevations, from 0-2600m (to 8500ft)).
With its red tubular flowers, Delphinium nudicaule is most often pollinated by hummingbirds. For this reason, it is a bit of an oddity within the genus, as most Delphinium species are blue or purple-flowered (e.g., Delphinium nuttallianum and Delphinium glaucum) and bumblebee-pollinated. Another oddity is that the mature shape of the Delphinium nudicaule flowers more closely resembles the flower buds (unopened flowers) of other Delphinium species than these other species’ opened flowers. For example, in bumblebee-pollinated flowers, the two lower petals are expanded and form a landing platform for the bees; in the hummingbird-pollinated flowers of Delphinium nudicaule, these petals are much reduced (as if they never fully reached maturity) and positioned off to the side to help hummingbirds access the nectar.
These observations spurred Edward O. Guerrant, Jr. to investigate the evolution of the Delphinium nudicaule flower (publication of his findings: Guerrant, Jr., E.O. 1982. Neotenic Evolution of Delphinium nudicaule (Ranunculaceae): A Hummingbird-Pollinated Larkspur. Evolution. 36(4): 699-712.).
On the topic of flower colour, Guerrant Jr. asserted that “the evolution of red flower colour from a blue-purple ancestor requires no explanation beyond a traditional view of selection by hummingbirds acting on existing variation.” However, with regard to flower shape, Guerrant Jr. suggests that the morphology of the Delphinium nudicaule flowers are a product of neotenic evolution, in which a developmental process is slowed or delayed such that the species retains traits at maturity that are only seen in the juvenile developmental stages of its ancestors. Guerrant Jr. writes: “In summary, the juvenile appearance of Delphinium nudicaule flowers relative to those of Delphinium decorum [a “typical” Delphinium flower form], can in part be accounted for, and was most likely produced by, the process of neoteny. In other words, although the flowers of both species have comparable times to maturity, those of Delphinium nudicaule do not progress as quickly through their mutual series of shapes, so their flowers end up looking like buds of Delphinium decorum. The resulting tubular flower shapes represents convergent evolution onto a floral form that is commonly visited by hummingbirds.”