QuickTime animations:



                        Competition for space

honda.mov  15s  (Figure 5)

In this model, two planar branch tiers compete for space. The circles represent
leaf clusters, located at the nodes. The endpoint of each branch, or apex,
produces new branches, unless it falls into an existing cluster.

This interaction limits the extent of branching, and adapts the shape of each
tier to the presence of its neighbor.



	               Clonal plant propagation
 
clover.mov   45s  (Figure 7)

This is the top view of a ground area, with different intensities of incoming
light. A clonal plant propagates by means of horizontal spacers which connect
the individual leaves. Old spacers and leaves die.

The plant takes advantage of high light intensity by increasing the frequency
of branching and decreasing the length of the spacers. Collisions are avoided
as in animation honda.mov.

After colonizing the patch at the bottom left corner, the plant searches for
another favorable patch. In its first attempt, the top right patch has been
missed. The plant tries again, and this time succeeds.

Light conditions in the top right patch are not sufficient to sustain the
continuos presence of the plant. The colony disappears until the patch is
reached again by a new wave of propagation.

The dynamics of propagation reflect the plant's adaptation to its environment.



		  Development of a root in soil (2D)

root2d.mov  18s (Figure 9)

The field surrounding a plant may be created by various physical processes. In
this case, field values represent concentrations of water, diffusing in
soil. The tip of the main root follows the gradient of water concentration. The
main root and the rootlets also absorb water from the environment.

The resulting developmental pattern reflects a cycle of interactions in which
the environment affects the root, and the root reciprocally affects the
environment. 



		   Development of roots in soil (3D)

root3d.mov  20s (Figure 10)

This is a three-dimensional extension of the model in animation root2d.mov. 
Water concentration is visualized by a semi-transparent iso-surface surrounding
the roots. The growing tips of the roots and rootlets absorb water that
diffuses in the soil. As a result of competition for water, the roots grow away
from each other.

Rotations highlight the resulting three-dimensional structure.

If the rootlets spread out less extensively, the area of influence of each root
system is smaller, and the roots grow closer together.



		   Competition of branches for light

trees.mov   16s (Figure 14)

In this simulation, two genetically identical trees compete for light from the
sky hemisphere. Clusters of leaves, not shown to make the branching structure
clearer, cast shadows on branches further down. An apex in shadow does not
produce new branches. An existing branch whose leaves do not receive enough
light dies and is shed from the tree. Competition for light controls the
density of branches in the tree crowns. 
Moving the trees apart reveals the adaptation of crown shape to the presence 
of the neighbor tree.