Gu Zhu Zi Sun (紫笋) is a green tea from Changxing County in Zhejiang Province of China. The name Zi Sun ("purple bamboo shoots") comes from the unopened leaf shoots, which shimmer purple. Gu Zhu is the name of the village where the tea originates from. Gu Zhu Zi Sun was very popular during the Tang Dynasty. This is mainly due to the influence of Lu Yu, who preferred the tea and promoted it intensively.