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On the Cover: Does hydrotropism guide the growth of the pollen tube on the surface of the stigma? By immersing Nicotiana alata pollen in stigma exudate or an oily medium close to an interface with an aqueous medium, Lush et al. (pp. 733-741) were able to show that pollen tubes always grow toward this interface. They postulate that a gradient of water in stigma exudate is an important guidance clue for pollen tube growth. The image on the cover shows a pollen grain immersed in oil with the aqueous medium at the bottom. When this image was taken, the growing pollen tube had just penetrated the aqueous phase, 135 minutes after the addition of the aqueous phase triggered germination of the pollen grain.