Which plant family is known for having compound leaves and flowers that resemble a pea blossom?

The plant family known for having compound leaves and flowers that resemble a pea blossom is Leguminosae, commonly known as the legume family. This family is characterized by its unique flower structure, which typically includes a banner petal (the large upper petal), two wing petals, and a keel formed by the fused lower petals, creating a structure that is reminiscent of a pea flower.

Additionally, many members of the legume family, such as peas, beans, and clover, feature compound leaves, which are composed of multiple leaflets attached to a single stem. This adaptation is prevalent across various species within the family, providing advantages such as increased surface area for photosynthesis and potentially reduced herbivory.

The other plant families listed do not share these characteristics to the same extent. For instance, Rosaceae primarily features simple leaves and a diverse array of flower structures, while Euphorbiaceae has a more varied inflorescence and leaf structure. Polygonaceae often has simple, broad leaves rather than the compound structure typical of legumes. Therefore, the distinct combination of compound leaves and pea-flower resemblance firmly places Leguminosae as the correct answer.