So named because of the shape of its juvenile form, the lancewood, or horoeka, is a small New Zealand tree that grows to 15m. As it develops it undergoes a remarkable transformation. The juvenile’s leaves grow downwards from a central stem and are stiff and serrated with a prominent central rib, while its trunk is distinguished by vertical ridges. As the tree matures the stem begins to branch and the leaves lose their teeth, become wider and shorter and create a bushy crown and more typical tree shape. Suggested reasons for this dramatic modification include a genetic response to climatic changes as the tree matures and its resources are reallocated. But perhaps the most interesting theory is that this difference was a response to moa browsing; once the tree grew above moa (see icon 42) height it no longer needed the special defence provided by its toothed juvenile leaves.