Walkers are dwarfed by the trunk roots of Rātānui, the largest living northern rātā. It grows in Bushy Park Reserve, just north of Whanganui, and has a trunk diameter of 3.7 metres. Northern rātā (Metrosideros robusta) is one of the giants of lowland conifer–broadleaf forest. It usually starts life as an epiphyte on a high branch of a canopy tree. Later it sends down roots to the ground. Eventually the roots enlarge and merge into a pseudo-trunk.