バイエルさんのインスタグラム写真 - (バイエルInstagram)「A single ragweed plant can produce about a billion grains of pollen per an average season and each grain can travel as much as 400 miles. It is also the main allergen for hay fever sufferers in the United States. Climate change may be contributing to cause ragweed in some locations to grow faster, produce more pollen and be more allergenic.」5月6日 0時39分