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Calathea Plant

Q.Interesting Rattlesnake plant (Calathea lancifolia) behavior…

Zone Harrisburg, PA | Pongo590 added on January 14, 2019 | Answered

I have a Rattlesnake plant (Calathea lancifolia). It has lovely markings and has many interesting characteristics.

One of the most interesting characteristics is its ability to close at night and open again in the morning much like a Prayer Plant. I have had it for over a year and a half and it always opens and closes daily.

My question is, why does it do that? My first thought was its due to sunlight or lack of it to open and close. However, I think I would be wrong if I were to say that. Why? Well, a recent test will explain my skepticism as light being the only reason.

Recently, I took my Rattlesnake plant after it had closed up for the evening. I put it in a completely dark walk-in closet away from any light. I even put a light blocker at the bottom of the door. This is the same closet I used for successfully causing poinsettias to recolor.

After placing the Rattlesnake plant in the totally dark closet overnight, when I came to get it the next morning at 9am, IT ALREADY WAS FULLY OPEN!!! There was NO LIGHT in that closet, not even a little. SO HOW did the Rattlesnake plant know to open? Do these plants develop some type of “clock mechanism” that they somehow sense what time it is and open up? It cannot be ascribed to light alone causing them to open. Some other mechanism is at work here. What is it?

Thank you…

A.Answers to this queston: Add Answer
Certified GKH Gardening Expert
Answered on January 14, 2019

This is a response to light, but to answer your question they DO have an internal "clock" so to speak. In fact, humans seem to be one of the few species to which the internal clock is starting to break down. Almost all other species have an internal mechanism for sensing time.(arguably multiple mechanisms.)

You can test this by leaving it in the closet for several days, and making sure that not a bit of light get in. They leaves will remain closed, respiration will stop and the plant will begin its degradation process. Unfortunately, this will kill your plant, or bring it very close to death.

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