Not much has changed
Gillespie and Virgil drive through Endicott Cotton Co. on their way to investigate Colbert's murder. The imagery reveals how very little has changed in the South as black folks are still picking cotton on the land owned by white folks. The image cuts deep to the wounds of slavery in America and how though laws have been passed, very little appears to have changed.
The Boot
We see Virgil in Gillespie's office and the Sheriff's boot is in plain view on top of his desk and pointing towards Virgil. The imagery reveals to us how Gillespie feels about Virgil: he wants to squash him, and believes him to be insignificant as if an ant under his boot. And the composition makes us feel the violence in Gillespie even when he is talking low and slow.
Endicott
Mr. Endicott is seen in the greenhouse growing orchids when Virgil and Gillespie call on him. The imagery is quite the contrast to having just seen black workers picking cotton in the fields. Cotton is sharp and can easily cut ones fingers and provides for a grueling day of hard labor, while growing orchids is a delicate process that would rarely cause one's hands to be hurt in the process, and the orchids aren't at ground level but are brought up to waist height--meaning they won't cause the back to break as they are being tended to.
Osmenda
We watch as Endicott tells Virgil that osmenda is what the orchids thrive on to grow. The imagery is important as Gillespie gets up to go because osmenda is what was found in Colbert's car and is a key piece of evidence to solving the murder.