| The invasion of weeds such as horehound and stemless thistles is a continuing management problem. |
| It has purplish flowers and lacks the woolly white appearance of white horehound. |
| It is native to the same regions as white horehound and is considered an invasive species in some parts of North America. |
| Areas once graced by desert mariposa tulip, Rocky Mountain bee plant, prickly poppy and evening primrose were invaded by the hostile horehound. |
| Soothes and protects skin irritated by shaving, thanks to the plant extract of white horehound. |
| Marsh fern, water horehound, spotted touch-me-not, great water dock, and lake sedge live on the soupy mudflats. |
