Guttation

When we look at a plant, it looks to be a very simple mechanism. We see a plant, grows tall, then comes flowers and fruits and then in some years grows into a tree. It does all this remaining in the same place, unlike most life forms. So, it has to take its food from the same place, protect itself, reproduce, throw out waste. All that remaining in the same place. So, its indeed a very complex process.

One key aspect of plant life is guttation. This is very different from transpiration. So, let us not confuse ourselves. Plants take in water and minerals from the soil, absorb sunlight and using the process of photosynthesis generate their food and grow. A very important aspect is that plants must balance the amount of water and nutrients they take in. The process by which plants balance the amount of water they take in is called guttation.

Plants like grass, wheat, tomatoes etc: have a vascular system. In these plants, the water accumulates at the tip of the leaves. This is called guttation. The process of guttation relies on pressure. So, this cannot happen in large trees, because the pressure that is required to force the water out is too large.

The process of guttation happens at night especially if the soil is moist and the roots absorb too much water. In case there is excess water, the root pressure forces the water out of the tips of the leaves or the blades of the plants. During the process when water undergoes guttation it will also pick up minerals and enzymes, such a process is called a xylem sap.
However, as mentioned earlier there is a difference between guttation and transpiration.

Water is vital for plants. So, most of the key terms of plants always relate to water. The two words guttation and transpiration are also related to water in plants. Guttation in plants happens when the stomata are closed but transpiration in plants happen when the stomata are open.

So, guttation happens when the climate is cold and humid which is mostly during the night or very early in the morning. Transpiration occurs during the day when it is dry and hot.

During transpiration water is excreted in the form of water vapor but in guttation, it is secreted as xylem sap. 

Transpiration process relies on the stomata. Stomata are small pores found on the surface of leaves. Plants use the stomata for another process also called photosynthesis. Photosynthesis cannot happen at night as it needs sunlight, so the stomata are shut during the night. The plant still needs to push out the excess water and they do it through another way called the hydathodes. Hydathodes are like stomata, but they cannot open and close like the stomata. They just permit the water to slowly secrete from the plants. 

 
Guttation fluid can contain quite a few organic and inorganic compounds like sugars and potassium. Sometimes high levels of insecticides have also been found in guttation liquids. 

 
Last but not least guttation should not be confused with dew. Dew is basically the condensation from the atmosphere onto the leaf surface.