Which of the following statements is incorrect about dicotyledons?

Options

A. Their root system mostly consists of tap roots only.
B. Their leaves have mostly reticulate venation.
C. The vascular bundles in their stems mostly are arranged in a ring.
D. Their flowers are mostly trimerous.

Explanation

To determine which statement is incorrect about dicotyledons, we can analyze each option provided:

1. **Root System**: Dicotyledons typically have a tap root system. This means they have a main root that grows deeper into the soil, which is characteristic of dicots. This statement is true.

2. **Leaf Venation**: Dicotyledons usually exhibit reticulated (net-like) venation in their leaves. This is in contrast to monocots, which have parallel venation. This statement is also true.

3. **Vascular Bundles**: In dicotyledons, the vascular bundles in their stems are primarily arranged in a ring formation. This arrangement allows for efficient transport of water and nutrients. This statement is true as well.

4. **Flower Structure**: Dicotyledons typically have flowers with parts in multiples of four or five (e.g., five petals). The statement that their flowers are mostly trimeric (in multiples of three) is incorrect, as trimeric flowers are characteristic of monocots.

### Conclusion:
The incorrect statement about dicotyledons is that their flowers are mostly trimeric.

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