Nguyen, Thanh Son, 1. University of Chinese Academy of Sciences, 100049 Beijing, People’s Republic of China: 2. Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, People’s Republic of China. 3. Tay Bac University, Quyet Tam Ward, Son La Province, Vietnam, Viet Nam