Myosotidium is a genus of plants belonging to the family Boraginaceae. This genus is represented by the single species Myosotidium hortensia, the giant forget-me-not or Chatham Islands forget-me-not, which is endemic to the Chatham Islands, New Zealand. Though it occurs only on the Chatham Islands, a 2011 DNA study found that its closest relatives are in the Mediterranean, suggesting extremely long distance dispersal of the winged seeds. The closest relative found was Mediterranean Omphalodes nitida. The two genera diverged between 3.64 and 22.45 Ma. The two genetic sequences differ by 5.3%