Double plants get generated without bottom part

The bug

When you enter a newly generated world you sometimes find double plants without a lower half. These are not a ghost blocks, because after reloading the world they are still there, however after some seconds they disapear like other "wrong placed" flowers (for example: flower on sand) and also right clicking them causes them to become the upper half of a sunflower.

Example seeds and coordinates

Seed: 3046059794814170817
X: -140
Y: 64
Z: 235
/tp -136 67 235 -173 37

Seed: 292202
X: 70
Y: 66
Z: 267
/tp -63 70 261 40 80