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A 4 day cress seedling showing a phototropic response towards a stationary unilateral light. Note the rapid curvature of the hypocotyl towards the light but the upper regions of the hypocotyl straighten (autotropism) after some hours even though the phototropic response of the seedling overall continues. The frames (320 x 240) were captured every 15 min and the duration of the sequence is nearly 12h.

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