New Zealand's geographical isolation has meant the country has developed a unique variety of native flora.
However, human migration has led to the importation of many other plants (generally referred to as 'exotics' in New Zealand) as well as widespread damage to the indigenous flora, especially after the advent of European colonisation, due to the combined efforts of farmers and specialised societies dedicated to importing European plants & animals.
New Zealand has a greater density of liverworts than any other country, due to its cool, wet and temperate climate.
A three-volume work on liverworts in New Zealand is being written by John Engel and David Glenny, with the first volume published in 2008.
Most New Zealand mosses originated in Gondwana, so there are strong relationships with species in Tasmania, South-eastern Australia, and temperate parts of South America.