The flowers of Manulea platystigma are two-lipped. The upper lip has four finger-like petal lobes, the lower single lobe could have been thought of as an opposing thumb, if it hadn’t been longer than the others.
The flower tube, whiter than the corolla lobes, has a kink behind the flower mouth, similar to that which is found on Jamesbrittenia flowers generally (iSpot; JSTOR).