Wu Zheng-yi and Peter H. Raven (eds.). 1999. Flora of China, Volume 4. Beijing: Science Press; St. Louis: Missouri Botanical Garden.
This fine volume is cited and quoted extensively in the Database, as it provides the only current English-language descriptions for a large number of species. The Flora is available online. Go to http://www.efloras.org (search page) and search for the taxon of interest by its scientific name.