Despite the fact that the alpine flora in New Zealand is considerably richer in species than the forest flora, its derivation poses the more puzzling problem. This is because geological evidence indicates that the present high mountains with their cold climates are relatively recent. In fact, for all except the last few of the past 100 million years it is suggested that New Zealand had warmer climates than now and much lower relief. In these circumstances it is difficult to imagine any habitats suitable for cold-tolerant plants that could have formed a nucleus for the present diverse alpine flora.