Dewdrops on Blades of Grass
July 15, 2007
When I woke up on a Saturday morning earlier this spring, it was clearly time to mow the lawn. The only thing that gave me a stay of having to execute this chore was the heavy amount of moisture on the grass --not good for the lawn mower. Instead, I set the camera to macro and snapped this picture. Note that all the drops formed on the tips of the grass blades. While often confused with dewdrops, these drops aren’t dew at all. Rather, it’s guttation. Whereas dew forms all over individual blades from condensation of atmospheric moisture, guttation just occurs on their tips. When there’s a high amount of soil moisture present, water enters plant roots and accumulates within the plant, which creates a slight root pressure. This root pressure forces some water to be exuded through specialized edge structures (hydathodes) at the leaf tip – forming drops. Notice also how the pinhead-sized drops refract the background light into perfect focus. Photo taken from Salem, Oregon on March 17, 2007. Thanks very much to Lee Grenci (Penn State University) for his help with this.