Lily pistils bend toward light.

Flower shape shows up and down features in many cases. Pistils of lily flower, Lilium cv. 'Casablanca', bend upward by sensing exclusively light. There found no sediment amyloplast in pistil corresponding to the absence of gravitropism. Fine granules of amyloplast disappear from pistil and tepal after opening of flower, except stomatal guard cells distributed on their epidermis. Bending of pistil caused by phototropism occurs when rate of its local elongation passes maximum and decreases. Elongation of pistil starts from its basal part close to ovary, and propagate toward distal tip afterwards. Bending of pistil follows this propagation. Because of this feature, curvature of pistil tends to be rather steep at the basal part. From spot irradiation experiment, site of sensing light was found not spatially separated by twice of diameter from site of bending.