Side by side
What tells them apart
Blue to violet flowers and much narrower, almost linear leaflets. The seeds are small and mottled, not large and white. It is just as bitter raw.
Confusion that poisons
How to tell it
A sturdy upright plant, up to a metre. An open-hand leaf with five to nine leaflets from the same point, silky-hairy underneath. White flowers, often tipped bluish, in an upright spike at the top of the stem. A broad flattened pod, covered in hairs, with three to six LARGE flattened white seeds. Narrow-leaved lupin has blue to violet flowers and much smaller, mottled seeds.
How to tell it
Palmate leaves with five to nine very narrow leaflets set in a whorl from one point, like the spokes of a wheel. A loose spike of violet-blue or lilac flowers. Hairy flat pods with three to seven smooth seeds mottled brown and white.