Rent Shop Volunteer Join

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

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

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

Science Fair Question
December 12, 2011 - Dear Mr Smarty Plants, I'm working on a project for the science fair and I need to find a plant that can survive in all climates in order for my experiment to work. What plant should I use? I hope ...
view the full question and answer

Why is my 3 year old Redbud not flowering in San Marcos, TX?
March 24, 2010 - My Cercis canadensis var. mexicana, purchased at the Lady Bird Johnson Wildflower Center, is 3 years old, very robust, but has never bloomed. Any explanation?
view the full question and answer

Where do snake herb and skeleton-leaf goldeneye get their names?
October 05, 2014 - Dear Mr. Smarty Plants, Where does snake herb, and skeleton leaf goldeneye get their names from? Thank you.
view the full question and answer

Least common flower color
June 14, 2008 - What is the least common flower color in the world?
view the full question and answer

Purple leatherflower with white bloom
July 17, 2014 - A couple of years ago at the wildflower center native plant sale I bought a purple leatherflower according to the tag. This is the first year it has bloomed and the blooms are pure white. The shape ma...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.