Monographs Details: Mazus macrocalyx Bonati
Authority: Li, Hui-Lin. 1954. The Genus Mazus (Scrophulariaceae).
Discussion:According to Bonati, this species is near M. japonicus (Thunb.) Kuntze, differing chiefly in the calyx which is about 5-10 mm. long and becoming accrescent to 30-35 mm. in diameter. In his key, however, he mentioned that the calyx attains to only 15-20 mm. in diameter. In the herbarium of the New York Botanical Garden, there is a Henry specimen [Yunnan: Lun-nan District, A. Henry 13761 (NY)], which may be referable to Bonati's species. tt has a calyx measuring up to 20 mm. in diameter. No specimen with a calyx over this size has been observed. It is altogether doubtful that this species is actually distinct from M. japonicus specifically.