Flag,

Flag, a popular name for many monocotyledonous plants with sword-shaped leaves, mostly growing in moist situations. It is sometimes particularly appropriated to the species of Iris (q.v.) or Flower-de-luce, especially to the common yellow flag (I. pseudacorus); but is given also very indiscriminately to other plants of similar foliage, as the Acorus calamus (see ACORUS), which is called Sweet Flag. It is even frequently applied in the United States to some of the algæ—e.g. Fucus (q.v.).