Columbian Larkspur (Delphinium trolliifolium)

More size information here.
A great pollinator plant that is rabbit and deer resistant!

This is the largest of our native larkspurs, with large bewitching blue flowers. It is usually found along shady streambanks near the Columbia River Gorge. Its flowers appear early in the spring, and are excellent forage for pollinators, like the Bombus californicus pictured above. Like other Larkspurs, Columbian Larkspur is poisonous – it also goes by the name Cow Poison! It is poisonous to all mammals, which makes it a great option for gardens that struggle with deer and rabbit browse.