Heliotropism is described for the flowers of four species of arctic plants.Only one, Papaver radicatum is heliotropic throughout the 24 hours of sun.The others, Dryas integrifolia, Matricaria ambigua, and Senecio congestus are heliotropic for several hours centered about solar noon.Heliotropism is abolished in cloudy weather.The significance of heliotropism is discussed in relation to intra-floral temperatures and reproduction.
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Peter G. Kevan (1972) studied this question.
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