The almost white to slightly pale brown flowers of Wahlenbergia thunbergiana are cup-shaped. The five acutely pointed petal tips spread in a star-shape or recurve strongly as in the photo, arching back away from the deep cup to nearly its base.
A thin dark vein-line is present along the centre of each petal, sometimes with perceptible, sparse side-branches. A pair of faint, also longitudinal, secondary veins may flank it about halfway to the margins.
The sturdy style is erect, well above the rim of the corolla cup, in picture faintly bluish near the three thick, short stigma branches that curve out. Their inner surfaces appear brush-like from short, fleshy protuberances growing densely together.
By the time the flower is properly open as here, the five stamens that grow from the petal bases are withered, their shrivelled white filaments visible low down in the cup (Le Roux, et al, 2005; iNaturalist).