Marginal placentation is a characteristic feature of legumes.

Answer

### Step-by-Step Solution

1. **Understanding Placentation**:
- Placentation refers to the arrangement or distribution of ovules within the ovary of a flowering plant. The ovules are attached to a structure known as the placenta.

2. **Defining the Placenta**:
- The placenta in plants is a parenchymatous cushion that supports the ovules. It is located inside the ovary, which can have one or more placentas.

3. **Types of Placentation**:
- There are several types of placentation, including marginal, basal, apical, parietal, axial, and dispersed. Each type describes a different arrangement of ovules within the ovary.

4. **Focusing on Marginal Placentation**:
- In marginal placentation, the ovules are arranged in one or two alternate rows along the wall of the ovary, specifically along the ventral suture (the fusion area of the ovary margins).

5. **Characteristics of Marginal Placentation**:
- This type of placentation is typically found in unilocular ovaries (ovaries with a single cavity) and is associated with the legume family (Leguminosae or Fabaceae).

6. **Examples of Plants with Marginal Placentation**:
- Common examples of plants exhibiting marginal placentation include members of the legume family such as *P. cassia* and *Acacia*.

7. **Conclusion**:
- Therefore, the statement that "marginal placentation is a characteristic feature of legumes" is true, as it accurately describes the placentation found in this family of plants.