What are the leaves below the tree covering?
The leaves are covering the ground.
    src        edge_attr  dst
0     0  to the right of    9
1     0   to the left of    1
2     1  to the right of    0
3     2     scattered on    5
4     2         covering    6
5     2         lying on    6
6     2            below    9
7     4           behind    9
8     5             near    8
9     6       covered by    2
10    8   to the left of   10
11    8             near    5
12    9   to the left of    0
13    9      in front of    4
14   10  to the right of    8
15   10         lying on    5