Sky lupine is the low-growing annual lupine that turns the flanks of Mt. Tamalpais blue in the spring, and many, many other parts of California as well. It is often found growing with California poppies and is almost as frequently seen. It also persists along roadcuts growing by itself, even in a dry year.
The thick seed-coats of lupine seeds need sufficient moisture in order to soften, allowing germination to take place, yet even in a dry wildflower year, it somehow shows up. Like most of the annual wildflowers, sky lupine prefers full sun and lean soil.
It is a host plant for the Painted Lady butterfly.