For many islands, we still don't know which species are rare and threatened. The challenge here is field surveys to find out. On some islands, the flora has been devastated. The best known case is Hawaii, which has the greatest number of recorded threatened plants of all islands in the world. Fortunately a long-term rescue programme in collaboration with Kew is attempting to save what remains.
Easter Island demonstrates a remarkable cautionary tale of devastation of an island flora.
Polynesian colonists destroyed the native forests of endemic Sophora toromiro and were then unable to leave the island because they had not enough wood for ship-building. Over-population led to starvation, civil war and collapse of their civilization. Other data are taken from the WCMC database and unpublished material by H. Synge.