My cats love to nibble on grass, and so I grow tack oats (Avena sativa) from seed for them. About six months ago I figured out that on cool, humid mornings the grass could be seen guttating. At the time I lacked my macro lens, and so did the best I could and got this image. It’s an okay image, but I don’t like the choice of background in retrospect, and I also wanted to get in closer and show just a few stalks of grass so the water drops would be more obvious.
Over the weekend some newly planted grass was again demonstrating guttation, so I tried anew:
Guttation is caused by root pressure building up so that water is squeezed out pores (hydathodes) at the tips or sides of a plant’s leaves. It typically happens at night, under cool, moist conditions when the soil is well hydrated. As Wikipedia says, it’s important to note that guttation and dew are two completely separate phenomena.
To demonstrate guttation in a typical botany science lab , a technician sets up a few-weeks-old pot of grass under a bell jar, waters it thoroughly, and leaves it for the night. The next morning tiny drops of water cover the plant’s leaves. One thing I like about my example is that it’s free of lab manipulation: this pot of grass was just sitting on my porch when I saw the guttation and brought it in to photograph.
If you’re curious how I photographed these, I used a technique much like1 that used with my poinsettia flower closeups; see my behind the scenes post for more details.
To see more of my botany-related pictures, head to my Botany Demonstrations gallery.