calla \cal"la\ ka^l"l.a, n. linnaeus derived calla fr.
   gr. ??????? a cock's wattles but cf. l. calla, calsa, name of
   an unknown plant, and gr. kalo`s beautiful. bot.
   a genus of plants, of the order araceae.
   1913 webster

   note: the common calla of cultivation is richardia
         africana, belonging to another genus of the same
         order. its large spathe is pure white, surrounding a
         fleshy spike, which is covered with minute apetalous
         flowers.
         1913 webster
see also:
araceae calla richardia africana