En EspaŅol

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
    
 
See a list of all Smarty Plants questions
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
 
rate this answer
2 ratings

Thursday - May 13, 2010

From: Brooklyn, NY
Region: Northeast
Topic: General Botany, Herbs/Forbs
Title: How do Venus flytraps really work?
Answered by: Nan Hampton

QUESTION:

How do venus flytraps *really* work? I've read it has something to do with the hairs in their "mouth," but is there a chemical reaction going on? A physical "trigger"? Help me understand the Venus Flytrap!

ANSWER:

There is an excellent article of the basics with photographs from Wayne's Word, Palomar College in San Marcos, California about carnivorous plants, including the Dionaea muscipula (Venus flytrap)

I will summarize the process as explained on that page and from other articles about the process:

The edge of the capture leaf has three sensitive hairs on the inside surface of the trap (the upper side of the leaf).  When an insect lands on the leaf and touches two or more of those sensitive hairs, or touches one of the hairs more than once, this precipitates a change in turgor pressure in the cells on the upper side of the leaf.  Since the cells lose liquid, this causes the leaf to fold over trapping the insect inside the leaf.  The stiff bristle-like hairs along both edges of the leaf interlock so that the insect cannot escape.  Once inside, glands on the inner surface of the closed trap release an enzyme that digests the insect and releases the nitrogen that the plant requires.  There is also a chemical aspect to the closing of the trap.  It apparently requires ATP (adenosine triphosphate), a nucleotide that serves as a biochemical energy source, to change the turgor pressure and close the trap.

It is agreed that the surface of the leaf changes shape.  When open, the upper surface of the leaf (where the sensitive hairs are) is convex.  When the trap closes that upper surface is concave.  The closing occurs rapidly—in 0.3 seconds (according to Alexander G. Volkov et al.  2008.  "Kinetics and Mechanism of Dionaea muscipula Trap Closing."  Plant Physiology 146:694-702).  The change in shape occurs because the cells on the upper surface lose fluid rapidly to the cells on the lower surface causing the upper surface to become concave and the lower surface to become convex, closing the trap.  As the insect struggles inside the trap, the sensitive hairs are further stimulated and the upper surface of the leaf loses more fluid and become more concave, thus further closing the trap. Charles Darwin had observed this and done experiments with the Venus' flytrap.  You can read Darwin's description of the Venus' flytrap online in Darwin, CR. 1875. Insectivorous Plants. London: John Murray. pp. 286-320.

The underlying mechanism of how the trap closes is still controversial, however.  Stephen Williams and Alan Bennett (1982. "Leaf Closure in the Venus Flytrap: An Acid Growth Response" Science 218 (4577): 1120-1122) suggested that a rapid lowering of pH (becoming more acid) caused the cell walls to loosen and change the turgor pressure between surfaces.  Others (DeGreef, see below) suggest it is an electrochemical mechanism responsible for the closure and Volkov et. al (see above) describes it as a "hydroelastic curvature mechanism".

You might like to read "How Venus' Flytraps Catch Spiders and Ants, Pt. 1"  in the Carnivorous Plants Newsletter 9 (3):65,75-78. 1980, and "How Venus' Flytraps Catch Spiders and Ants, Pt. 2" Carnivorous Plants Newsletter 9 (4):91,100. 1980 by Stephen E. Williams.

Also, "The Electrochemical Mechanism of Trap Closure in Dionaea muscipula" Carnivorous Plants Newsletter 17 (3):80-83,91-94. 1988 and "The Electrochemical Mechanism of Trap Closure in Dionaea muscipula. Addendum" Carnivorous Plants Newsletter 17 (4):106. 1988 by John D. Degreef.

Whatever the underlying mechanism is, it is truly an amazing plant!

 

More General Botany Questions

Fasciation on Texas Mountain Laurel
November 21, 2012 - Do Texas Mountain Laurel normally have a staghorn looking growth hanging on them after blooming in addition to the seed pod clusters or could this be a mutation?
view the full question and answer

Experiment to detect presence of sugar in cellulose from Routt CO
January 28, 2013 - My teacher ask me to plan an experiment to detect the presence of sugar in cellulose. I know that cellulose are abundant at the stem, and sugar here is glucose. I wonder how to conduct this experiment...
view the full question and answer

Define monoculture from St. Croix Falls, WI
May 30, 2014 - What do you call a dense stand or carpet of one species of wildflower? Our botany professor told us but that was 40 years ago!
view the full question and answer

Native plants as accumulators of heavy metals in Texas
March 29, 2008 - I would like to know of any native plants that could be used as hyperaccumulaters of heavy metals in Texas.
view the full question and answer

Smarty Plants on cell elongation
June 09, 2005 - Why do plants grow faster in the dark?
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP
© 2014 Lady Bird Johnson Wildflower Center