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

What do cedars do to cause cedar fever?
February 20, 2009 - What do the native cedars in Fate Tx do in the winter that causes allergies to get really bad that they have named it cedar fever
view the full question and answer

East Texas Natives and Botanical History
May 05, 2011 - I am looking for flowers &/or flowering shrubs that are native to east Texas, especially that would have been in this area over 100 or more years ago.
view the full question and answer

Strange form of Dasylirion sp. (sotol)
December 27, 2008 - Mr. Smarty: I have a client with a huge (2 ft. diameter trunk), multi-headed dasylirion. On one or more of the heads, the leaves arch inward instead of outward. Someone said this is because of an inju...
view the full question and answer

Disappearing sunlight in Phoenix, AZ
September 29, 2009 - I live in a condo in Phoenix, AZ with a north facing patio that goes out about 10 feet and is 20 feet wide. During the summer months there is a span of 1 foot in the front that goes the 20 foot length...
view the full question and answer

Half-life of the insecticide imidacloprid
March 07, 2011 - How long do systemic insecticides such as imidacloprid (Merit) remain active in nursery grown plants? Asclepias curassavica (tropical milkweed)is frequently grown with imidacloprid to prevent...
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