Clear beads line the tips and rims of leaves at first light, looking exactly like dew but pushed out from within. This is guttation: water and minerals released through hydathodes, a special class of stomata, when roots take up more water than the plant needs — a safety valve, without which veins and leaves might burst.
| Name | guttation |
|---|---|
| Common name | crying plant, weeping leaves, teary plant, dewdrop |
| Type | plant physiological process |
| Occurrence | often |
| Observation time | early morning |
| Affects | houseplants & low-lying plants |
This biological process enables plants to restore balance between their nutrient intake and needs.
→ Recently, science is realizing plants use guttation to communicate!
Guttation occurs when a plant oozes water and minerals out from perfectly healthy leaves, stems, and sometimes even flower petals.
It takes place when roots of a plant absorb more water than the plant actually needs.
Tiny, specialized cells on the surface of a leaf or stem are connected to veins and sap channels of the plant. This cluster of cells works as a nozzle. It releases water from the plant’s vascular system to the outside, forming drops that look like dewdrops.
This process where excess pressure is released from inside the plant is called guttation.
Hydathodes are usually placed around the rim or tips of leaves, on the leaf surface, or at junctures between leaves and stems.
About the term “Guttation”:
To understand why plants developed guttation as they evolved, it helps to brush up the following:
Hydathode nozzles are one of the biological tools plants use to regulate pressure inside them.
Water used to transport nutrients up and down the stems and leaves is called sap. But there are more uses of water in a plant than simply transportation! Here is a short list of how a plant uses water:
If ever you’ve opened a fresh coconut, you must have noticed that when the hull is slit, drilled or broken, coconut water spurts out. The pressure inside the coconut is higher than the pressure of the air around it. You can also see happen when slitting open a watermelon: the last few inches simply split open on their own.
Thanks to a combination of chemical reactions, tissue structure and cell components, a plant is able to control water in and around it.
Guttation is one of the ways excess pressure is released. If not for this, the plant might burst at weak spots of veins and leaves!
Guttation turns up in a handful of predictable situations. The table sets them side by side, with what pushes the sap and what the plant gains from letting water out.
| Situation | Why sap needs a push | What guttation achieves |
|---|---|---|
| Night-time and early morning | Evaporation and transpiration no longer work well | Roots push water up, and the excess is shed at leaf tips |
| Air near or above 100% humidity | The plant cannot sweat, even in daylight | Keeps sap circulating through the plant |
| Soggy soil around the roots | The plant must shed water it has taken up in excess | Evacuates water around roots and protects them from rotting |
| Seedlings and young plants | Young growth is more prone to the phenomenon | More drops than on older, established plants |
None of these situations is a fault to correct: each one shows the plant balancing the water it has taken in.
First off, not all plants guttate. For those that do, there’s a chance of seeing guttation in the following situations:
Plants breathe at night and still need sap to flow up and down the plant. Guttation takes over to force sap and water up when transpiration stops being effective.
When the air is near or above 100% relative humidity, it’s impossible for a plant to sweat.
It isn’t a common reaction, but guttation is one way of helping the plant evacuate excess water around roots. It’s a coping the plant uses to protect roots from rotting.
Seedlings and young plants tend to guttate more than older, more established plants.
Gummosis and latex flow are similar to guttation in that fluids are also expelled from the plant through controlled interfaces.
Bleeding, resulting from a wound to the plant, is different.
Dew and dewdrops are something entirely different, but are also useful to plants. Plants can maximize dew without being responsible for creating it.
Read also:
Guttation can even reach the point where sap drips to the ground. It can leave hard-to-remove stains on almost every surface, indoors and out!
So hose it away outside, and wipe it up indoors.
