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
7 ratings

Thursday - July 19, 2007

From: Centreville, VA
Region: Mid-Atlantic
Topic: General Botany
Title: Percentage of flowers that close up at night
Answered by: Joe Marcus

QUESTION:

Percentage-wise, approximately how many species of flowers close up at night? Is there a list anywhere?

ANSWER:

Mr. Smarty Plants would very much like to give you an exact number, a ball-park estimate, or even a swing-in-the-dark guess, but we really don't know of the information you're requesting having ever been collected and compiled anywhere. Are you up to the challenge? If we had to characterize its commonness, we would say that the number of species exhibiting nyctinastic flower response (closing at night) is a small percentage of the total number of flowering plant species, but an impressive number nevertheless.

Nastic movements are relatively rapid movements of plant parts (most often leaves and flower parts) in response to an external stimulus, but independent of direction. Nastic movements are distinguished from tropic movements (phototropism, gravitropism, etc.) which cause a directional response either toward or away from the stimulus.

Some examples of nastic movements include nyctinasty, which is night- or circadian-induced, thigmonasty or haptonasty, which is touch-induced, hydronasty which is humidity-induced, seismonasty, which is shaking- or vibration-induced, and thermonasty, which is temperature-induced. By the way, Mr. Smarty Plants proposes the term hydronasty be changed to hygronasty since the Greek root, hygro- specifically refers to humidity.

Much is known about the mechanism of nastic movements (how plants actually go about moving their plant parts) and about the causal stimuli. What really remains a mystery is why certain plants exhibit these responses at all. Theories abound, but it seems that all of the theories have shortcomings and there probably isn't a one-size-fits-all rationale for the various responses observed. Many plants exhibit nastic responses to an entire suite of stimuli.

While it is natural to assume that nyctinastic responses are immediate reactions to darkness, experiments have shown that plants will continue making nyctinastic movements at about the same time each day in continuous light or continuous dark conditions. Thus, the response is circadian in nature. After several days of either 24-hour light or 24-hour darkness conditions the effect will diminish. Nyctinastic movements often have a temperature-related (thermonastic) component.

 

 

More General Botany Questions

Plants named for Thomas Drummond
February 09, 2009 - Dear Mr. Smarty Plants, Please send list of plants discovered and named for Thomas Drummond.
view the full question and answer

Why is water used for plants.
February 19, 2008 - Why is water the most popular thing for watering plants if is so plain?
view the full question and answer

Process of transpiration in plants
November 21, 2005 - I'm in 6th grade and I have a science project to do and the question is, Do living plants give off moisture. The first part of my project is to explain how living plants give off moisture. I've chec...
view the full question and answer

Comments on article in Austin paper
January 22, 2012 - Why can't we comment on your piece in the Statesman? It says no comments possible at the bottom.
view the full question and answer

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

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