Mangrove roots are transparent in Fast graphics

The bug

Unlike leaves, mangrove roots can still be seen through in the Fast graphics setting. I'm not entirely sure if this is a bug, but mangrove roots feel like a block that should be opaque in this setting since leaves are.

How to reproduce

1. Place mangrove roots
2. Place leaves nearby for comparison
3. Set the graphics setting to Fast

Expected results

The leaves and roots would both be opaque.

Actual results

The roots remain transparent.