This is our common lupine, the arroyo lupine. It is found in great profusion on Jesusita trail where it coated hillsides in 2010, and also on Arroyo Burro (back), Blue Canyon and Forbush trails. It is a common roadside flower too. It prefers lower slopes to the high chaparral.
Easily distinguish from the miniature lupine because it is bigger with wider leaves, and from the spiny lupine because it has no hairs (spines), and from both because there are (usually) 7-9 leaves in the rosette rather than 5-6. For a long time I confused it with Canyon lupine, but the arroyo is slightly smaller and has a light green stem instead of a dark one.
It likes disturbed earth and quickly colonizes after a fire (hence the profusion on Jesusita trail after the Jesusita fire).
The flowers are blue and white. After being pollinated the white turns to red.