This riddle about plants describes a walnut by comparing it to a girl in a blue dress. Walnuts have thick, woody shells which are dark in color. The riddle's first sentence describes a girl in a blue dress. This description identifies a walnut, dark in color, but possibly not yet ripe. In the second sentence, the walnut's fruit is described as a filling in a fatty belly. Walnuts are calorically dense with fatty oils adding to their nutritional value. Overall, the riddle presents an endearing image of a familiar food.