The water caltrop of Zuoying is quite famous. Lots of foreign tourists bought water caltrop as a souvenir while they visited Zuoying. Last year, it, Zuoying Water Caltrop, won the award of the ten best Kaohsjung City's Specialties. Few people know why Zuoying Water Caltrop is famous; therefore, we made the study enable more people to know what "Zuoying Water Caltrop" is.