In nature we are aware of some of the environmental effects that dictate how a tree grows. These includes facts such as leaves growing towards the sunlight, roots towards water/nutrients and even how a prevailing wind can shape the tree branches. However, research has also shown that it is not only extrinsic effects which influence growth behaviour but also intrinsic effects.

When observing leaf size range scientists noted a correlation between the size of a trees leaves and its height. What was noted was that as a tree got taller the upper and lower boundary limits for leaf size became more defined. This culminated to a point where trees couldn’t seem to physically grow any higher as the upper and lower boundary limits crossed, resulting in no possible sizes for the leaves. This crossover happened at roughly 100m, which correlates with the tallest trees ever recorded. Why might this be?

Figure 1: Graph showing correlation between leaf size limits and tree height

What Jensen et al. [1] surmised is that this was due to the vascular system of the trees. As the tree increased in size the amount of fluid needed to meet the demands of the system led to an increase in the lower leaf size limit as larger leaves are needed to produce greater amounts of fluid. But, as the tree grows in height, the resistance of the trunk to incoming fluid flow also increased. This would result in a decrease of the upper limit of the leaf as larger leaves would produce more fluid than was being transported efficiently around the system.

What does this mean for us in Biohaviour?

As we explore Biohaviour, growth and the environment we should view the growth as being influenced not only by the environmental effects applied but also by its intrinsic characteristics. While the setting of the environment is important for defining the problem space there may also be factors, rules or patterns which pertain to the internal growth of the product. Creating internal rules within the system may help to ensure greater stability in the growth and is certainly an exciting route to explore when creating new shapes and patterns. What intrinsic characteristics do you think might create interesting new shapes? And which may be important to include to help develop exciting new products?


[1]. K. Jensen, M. Zwieniecki, “Physical limits to leaf size in tall trees”, Physical Review Letters, 2013