To test the hypothesis that the divaricate habit protects internal leaves from cold and dry conditions, and raises leaf temperatures on cold sunny days, thermocouples were attached to internal and external leaves on divaricate plants. For Coprosma propinqua plants at Cass, inland Canterbury, there were consistent differences in temperature between leaves, but these were not simply related to their canopy position (interval vs. external).
New Zealand forests grow under highly oceanic climates on an isolated southern archipelago. They experience a combination of historical and environmental factors matched nowhere else. This paper explores whether the New Zealand tree flora also differs systematically from those found in other temperate and island areas. A compilation of traits and distributions from standard floras is used to compare the New Zealand tree flora with those of Europe, North America, Chile, southern Australia, Fiji and Hawaii. New Zealand has a large number of trees (215 species ≥6 m in height).