What Are the Causes of Guttation in Plants?

Should you assume those drops of water on the leaves of your garden plants are always dew, you could possibly be wrong. Dew is moisture from the atmosphere and will cover the surface of a leaf, but if you only see droplets on the leaf edges, then you are seeing an example of guttation. This moisture results from the special physics of plant transfer.

Plant Transport Systems

Like all living things, plants will need to transfer moisture and nutrients to all of their tissues. Plants use xylem and phloem as the key vehicles for transfer. Roots pull in water and nutrients from the soil, which are then moved upward into the leaves and stalks from xylem. The leaves use the sun to create energy and food for the plant, which then travels downward into the stems and then the roots through phloem.

Moving Xylem

To get to the leaves from the roots, xylem must overcome the downward pull of gravity. Throughout the day, this can be accomplished by transpiration, a special type of evaporation through holes in the leaves called stomata. The evaporation makes a pull just like a vacuum to drag the xylem up from the roots. At night, transpiration slows in part due to the stomata close, but xylem still needs to stream or the plant will wilt. To do so, the cells from the roots make it possible for minerals to build up. This build up of antioxidants contributes to water, which generates pressure in the main cells. This pressure pushes xylem back up to the leaves.

Xylem and Guttation

Leaves can simply take in a short quantity of water. Throughout the day or in dry conditions, the excess water evaporates because of the sun or wind. At night, cooler temperatures, peaceful states and closed stomata mean that the leaves don’t lose just as much moisture as during the day. After the pressure in the main cells shoves water-carrying xylem up, the stress forces excess water from their leaves through special structures called hydathodes found at the tip and margins or leaves. Guttation mainly occurs at night, but it sometimes happens during the day in areas with high humidity.

Plants and Guttation

Guttation doesn’t occur in every plant. Trees, by way of example, are too large to create the force needed to push xylem upward hard enough to cause guttation. Plants that most commonly experience guttation are non-woody and smaller than 3 feet tall, but some shrubs and vines show guttation as well. Guttation is typically not a problem for plants unless your soil has a high mineral content. Once the water does disappear, the minerals become left behind and can burn the tips of their leaves. Lowering the quantity of fertilizer you use can avoid this burn.

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