Your plot should look something like this.
| Quercus rubra | 5-7 | 7-9 | 9-11 | 7-9 | 9-11 | 9-11 | 11-13 | 11-13 | 9-11 | 11-13 | 13-15 | 15-17 |
| Quercus alba | 11-13 | 9-11 | 5-7 | 9-11 | 11-13 | 7-9 | 7-9 | 7-9 | 5-7 | 7-9 | 7-9 | 5-7 |
Notice that two data points tells us almost nothing about how the data are distributed, or scattered, about the mean value. In fact, the present pattern is quite misleading. Now modify your plot to include the first six data points for each species.