Calla Lily Has Droplets at Tip of Leaves

In your Calla Lily water is absorbed through the roots and travels up through the plant. Most of the water taken up like this is 'lost' to evaporation. What water is left behind for the plant to use is for tissue growth, etc. The evaporation action works like a pumping station which pulls water (and fertilizer and anything else dissolved in the water) up through the plant. This is how plant tissues function. When a plant grows in very wet conditions, or is watered generously, it absorbs moisture and builds up pressure inside the cell walls. Holes in the leaves are forced open and water may drip giving the appearance that the lily is 'crying'.