It is also known as 'kengyu' (Cowherd) (its flower is called 'kengyuka') because in ancient China its seeds (called kengoshi) were so expensive and so valuable medicines that people who were given the seeds would thank the giver taking their cows with them.
別名「牽牛」（花は「牽牛花」）というが、これは、その種（牽牛子）が薬として非常に高価で珍重されたため、種を贈られた者はウシを牽いて御礼をしたという、古い中国の謂れである。