That's actually not dew. Dew is caused when a decrease in atmospheric temperature causes water from the atmosphere to condensate on random objects, and it does so randomly. There is a clear and obvious pattern in the water droplets in the Equisetum, which indicates that this is Guttation. Guttation is caused by an excess of water in the roots of the plant, which pushes the extra water out through specific places in the above-ground portion of the plant.
