Additive dispensing system for a washing machine appliance

A washing machine appliance defines a mutually perpendicular vertical direction, lateral direction, and transverse direction. The washing machine appliance includes a cabinet having an opening defined in and through a top cover thereof. A wash tub is mounted within the cabinet and a wash basket is mounted rotatably within the wash tub. The wash basket is accessible through the opening in the top cover. A dispensing assembly includes a dispenser box mounted above the wash tub, a shower plate positioned within the dispenser box and defining a plurality of water supply apertures, lateral suspension arms that extend downward from the shower plate along a vertical direction, and a detergent drawer defining one or more detergent reservoirs, the detergent drawer being directly supported by the lateral suspension arms.