The Schizoglossum bidens subsp. atrorubens flower has a dark calyx and corolla. The central corona is white. The five calyx segments are triangular, narrowly pointed and spreading. They are shorter than the five oblong corolla lobes alternating with them in a circle, curving in in their upper parts. Parallel, shaded lines are longitudinal on the inside surfaces of the corolla lobes. The lobe margins are hairy.
The white corona in the flower centre has five lobes that are short and round-tipped, alternating with the corolla lobes. This results in them being positioned directly above the sepals or calyx segments.
The stamens are united at the base in a hollow column from which the corona lobes arise. The ovary comprises two free carpels concealed in the staminal column (Leistner, (Ed.), 2000; Pooley, 1998; iNaturalist).