In Casuarina, the root apical meristem has sets of initials
Casuarina is a genus of oak tree species belonging to the family Casuarinaceae.
They are also known as ironwoods.
All the cells in the structure of roots can be traced back to few apical cells which are called initials.
In Casuarina, only two rows of initials are observed at the root apex.
One of the layers gives rise to the stele and the other to the cortex and root cap.
So, the correct answer is 'Two'.