The tallest tree in New Zealand is an Australian Eucalyptus regnans in the Orokonui Eco-sanctuary, a forest reserve just north of Dunedin. The largest tree known in New Zealand is the great kauri,...
My guess would be the group of Raoulia (vegetable sheep) which most folk wouldn't even recognize as a tree. Some have a height of 25mm or so, and have a dense cushion of small leaves densely...