Hedysarum: poisonous or not?

One of the few sources of starch in the boreal forest of Interior Alaska is the root of the common species Hedysarum americanum (Michx.) Britton, known as “troth” in Lower Tanana (Kari, Lower Tanana Dene Dictionary) and in English as “Indian potato” or “Eskimo potato”. However a similar species, Hedysarum mackenziei Richardson (“tsoni trodha'”; Kari, LTDD), co-occurs with americanum, and is apparently poisonous. Telling the two species apart is vital if you will be harvesting the root of americanum. Fortunately there are may characters to assist:

Comparison of Hedysarum species

Further information:

As an aside, Hedysarum americanum is one of my favorite species in Alaska: it’s the one with leaves that most remind me of the frequent pinnate, entire leaves of tropical forest.