marsh-plant found in colder parts of Europe and America, 1789, from Latin calla, the name in Pliny of an unidentified plant, perhaps a mistake for calyx. The common calla-lily (1805) is a related species, not a lily but so called for the appearance of the flowers.
caliper
caliph
caliphate
calisthenics
call
calla
caller
call-girl
calligraphy
calling
calliope