In the winter, the leaves of snakeroot shrivel up and turn brown, but they remain on the stem. My deer love those dry, dead leaves. I've watched them for years go from plant to plant and pick off the leaves and the dead stock remains standing. It's actually something that I look for during late season hunting. If I see a patch of snakeroot with all the leaves still hanging on, then I know deer must not be feeding very heavily in that spot. If I find a patch of bare stocks standing, I know where all the leaves went to...a deer's belly.
Snakeroot seems like a useless forest weed in late summer/early fall, but come late fall/winter, it's highly desired around here. Maybe some chemical reaction occurs as the leaves die and dry? Maybe the toxins leech out? IDK.