Kale (IMAGE) University of Oldenburg Caption Kale varieties with curly leaves produce more mustard oil glycosides at low temperatures. Credit University of Oldenburg / Ute Kehse Usage Restrictions Use only with proper credit and together with press release License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.