Word Study
Calendula
CIDE DICTIONARY
Calendula, n. [NL., fr. L. calendae calends.].
A genus of composite herbaceous plants. One species, Calendula officinalis , is the common marigold, and was supposed to blossom on the calends of every month, whence the name. [1913 Webster]
OXFORD DICTIONARY
Calendula, n. any plant of the genus Calendula, with large yellow or orange flowers, e.g. marigold.
Etymology
mod.L dimin. of calendae (as CALENDS), perh. = little clock
For further exploring for "Calendula" in Webster Dictionary Online