Yam Tuber (IMAGE) American Society of Agronomy Caption White Guinea yam tubers can be inconsistent in shape and size. Breeders will be able to use the collection of genetic resources to improve yam characteristics. Credit S. Yamanaka Usage Restrictions For use with this story only. 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.