Leaves one or two, rarely three, trifoliate, the leaflets ovate, slender-pointed, to 15cm long. Stalks 30-60cm in height. Spathe green or purple or green variably flushed with purple often, but not always, striped white or green, the blade arching over to form a hood, early summer. A very variable species in habit, size and colouring; plants originally called A. triphyllum have corms with scaly rhizomes, the former A. atrorubens does not. Eastern North America in moist woods and thickets. Hardy.