The yellow Wiborgiella leipoldtiana flower resembles the pea-flower in structure. The corolla has a reflexed banner without hairs on its outside. The banner petal is reflexed in the open flower, obtusely point-tipped and (in picture) folding in slightly along its midrib. The narrow, pointed keel is notably longer than the pair of wing petals on its flanks.
Flowering happens from before midwinter to after midspring. The photo was taken in September (Bond and Goldblatt, 1984; iNaturalist).