Pu-erh tea

„Pu'er traditionally begins as a raw product known as "rough" Mao Cha (毛茶) and can be sold in this form or pressed into a number of shapes and sold as "raw" Sheng Cha (生茶). Both of these forms then undergo the complex process of gradual fermentation and maturation with time.“

„Astringency
Astringency invariably accompanies bitterness. In some Puer the astringency is more pronounced, the bitterness slightly weaker. A benefit of astringency is that it can help promote salivation. If this is felt on the underside of the the tongue it is a further mark of good tea.“