Here is an example of a higher-dimensional phylogenetic "tree", as described by Bernd Sturmfels in the Mathematics of Phylogenetic Trees seminar.
This figure, created by Josephine Yu using polymake and displayed here using JavaView, came from the following distance matrix:
| Zebrafish | Tetraodon | Fugu | Rat | Mouse | Rabbit | Horse | Pig | |
| 0 | 0.38166 | 0.38224 | 0.47441 | 0.47132 | 0.44783 | 0.43305 | 0.44488 | |
| 0.38166 | 0 | 0.20756 | 0.43245 | 0.43225 | 0.42395 | 0.40943 | 0.41648 | |
| 0.38224 | 0.20756 | 0 | 0.43995 | 0.44269 | 0.42933 | 0.41666 | 0.42485 | |
| 0.47441 | 0.43245 | 0.43995 | 0 | 0.14313 | 0.35614 | 0.33370 | 0.34954 | |
| 0.47132 | 0.43225 | 0.44269 | 0.14313 | 0 | 0.35490 | 0.33096 | 0.34624 | |
| 0.44783 | 0.42395 | 0.42933 | 0.35614 | 0.35490 | 0 | 0.26176 | 0.28836 | |
| 0.43305 | 0.40943 | 0.41666 | 0.33370 | 0.33096 | 0.26176 | 0 | 0.19227 | |
| 0.44488 | 0.41648 | 0.42485 | 0.34954 | 0.34624 | 0.28836 | 0.19227 | 0 |
The figure shows the bounded complex projected to 3 dimensions. A spring embedder was applied to make it easier to see (so the figure doesn't reflect the actual metric). If you'd like to learn more, please visit this webpage.