| It is native to the same regions as white horehound and is considered an invasive species in some parts of North America. |
| It has purplish flowers and lacks the woolly white appearance of white horehound. |
| She recommends the use of psyllium for constipation, aloe for jaundice and horehound for cough. |
| Areas once graced by desert mariposa tulip, Rocky Mountain bee plant, prickly poppy and evening primrose were invaded by the hostile horehound. |
| One very remarkable minor feature was the appearance of couch-grass and horehound, which had sprung up around the stockyards. |
| The invasion of weeds such as horehound and stemless thistles is a continuing management problem. |
