monochlamydeous
/ˌmɒnə(ʊ)kləˈmɪdɪəs/Botany
adjective
Having only one series of perianth segments, i.e. not having the perianth differentiated into corolla and calyx; specifically (now rare ) belonging to the Monochlamydeae, a division or subclass of dictyledonous plants having flowers with only one series of perianth segments or sometimes no perianth, including the Chenopodiaceae, Euphorbiaceae, etc.
Origin
Mid 19th century; earliest use found in John Lindley (1799–1865), botanist and horticulturist. From scientific Latin Monochlamydeae, group name + -ous. Compare French monochlamydé.