Correct option is C

Since all trees are flowers and flowers cannot be plants, there is no overlap between roots (which are plants) and trees (which are flowers).
Therefore, Conclusion I does not follow.
Conclusion II: Some Plants are Trees. (False)
Since all trees are flowers, and no flower is a plant, which means trees cannot be plants.
Therefore, Conclusion II does not follow.
Thus, the correct option is (c) Neither conclusion I nor II follows.