Take no more than one-tenth of any patch, and never harvest a species from the only place you find it.
Roots, bulbs, and bark kill or maim the plant — harvest these only from genuinely abundant populations, and replant crowns and bulb scales where you can.
Some plants in this book are conservation-sensitive: American ginseng (CITES-listed, poached heavily — buy cultivated), goldenseal (endangered from overharvest — use Oregon grape instead), Oregon grape root (United Plant Savers At-Risk — use cultivated sources), blue camas and bitterroot (slow, culturally sacred — harvest lightly or not at all).
Invasive species are the exception: garlic mustard, Japanese knotweed, and kudzu harm native ecosystems — harvest these aggressively.
Leave no trace: fill digging holes, scatter seed heads, and pack out what you pack in.