Hosackia gracilis, synonym Lotus formosissimus, is a species of legume native to western North America from British Columbia through Washington and Oregon to California.

[1] It is known by the common names harlequin lotus[2] and seaside bird's-foot trefoil.

[3] It grows in moist spots in the coastal mountains and down to the oceanside bluffs.

It is lined with leaves each made up of a few oppositely arranged oval leaflets up to 2 cm long.

It is believed that the caterpillars of the critically endangered lotis blue butterfly (syn.