Which of the following subfamilies of Fabaceae is characterized by having flowers with inconspicuous, radially symmetrical features?

The subfamily Mimosoideae within the Fabaceae family is distinguished by its flowers, which are often characterized by having inconspicuous, radially symmetrical features. This subfamily features flowers that typically have small, tubular structures arranged in dense heads or spikes, presenting a fluffy or pom-pom appearance. They lack the prominent symbolic features found in other subfamilies, such as the distinct petal shapes commonly seen in Papilionoideae.

In contrast, other subfamilies like Papilionoideae typically exhibit more colorful and morphologically diverse flowers with clear bilateral symmetry, which means they have one side that is different from the other. These flowers are often highly specialized and adapted for pollination by specific insects.

Caesalpinioideae also contains flowers that can exhibit variations, but they are often more visually distinguished than those of Mimosoideae and may have noticeable features while still being distinct from the conspicuous flowers of Papilionoideae.

Therefore, the defining characteristics of Mimosoideae's flowers verify it as the correct choice when identifying the subfamily characterized by inconspicuous and radially symmetrical floral features.