Dicot root is similar in all the given characters to monocot root, except.

Answer

To solve the question regarding the differences between dicot and monocot roots, let's break it down step by step:

### Step 1: Understand the Structure of Dicot and Monocot Roots
- Dicot roots typically have a structure where the xylem and phloem are arranged in a radial pattern. This means that they are arranged alternately in different radii.
- Monocot roots also have a similar arrangement of xylem and phloem, which is radial.

**Hint:** Look for the arrangement of vascular tissues in both types of roots.

### Step 2: Examine Vascular Bundle Arrangement
- In both dicot and monocot roots, the vascular bundles can be described as exarch. This means that the protoxylem is located towards the outer side (periphery), while the metaxylem is located towards the inner side (pith).

**Hint:** Remember the terms protoxylem and metaxylem when considering vascular bundle arrangements.

### Step 3: Consider Root Hair Characteristics
- Both dicot and monocot roots have unicellular root hairs. This is a shared characteristic between the two types of roots.

**Hint:** Think about the function of root hairs and their cellular structure.

### Step 4: Analyze the Role of Pericycle
- The pericycle in both dicot and monocot roots plays a role in forming lateral roots. This characteristic is also common to both types of roots.

**Hint:** Focus on how lateral roots develop from the pericycle.

### Step 5: Identify the Key Difference
- The major difference lies in the development of the pith. In monocot roots, the pith is well-developed, while in dicot roots, the pith is not well-developed or may be absent.

**Hint:** Compare the pith structure in both types of roots to find the distinguishing feature.

### Conclusion
The correct answer to the question is that the dicot root is similar to the monocot root in all the given characters except for the presence of a well-developed pith.

**Final Answer:** The well-developed pith is the characteristic that differentiates dicot roots from monocot roots.