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

Monocarpic plants for Indiana
October 06, 2005 - We were in Hawaii this summer and became acquainted with the Silversword. This plant (according to what we were told) blooms only once in it's lifetime (of 50-70 years). Are you aware of any other pl...
view the full question and answer

Smarty Plants on plant names
March 16, 2005 - I want to learn what the scientific names of plants indicate about the plant physiology, its namer, its evolutionary relation to other plants, etc. Could you give a print or web source for looking up ...
view the full question and answer

Key for Verbesina virginica
June 16, 2014 - Are the stems of Verbesina virginica hairy? My in-laws have what I believe is Verbesina virginica (blooms in September here in VA) and another wild flower that blooms before it and is yellow. I'd l...
view the full question and answer

Compare Natives to Lawn for Carbon Footprint Benefits in Durham, New Hampshire
September 22, 2010 - Are there carbon sequestration rate tables for turf (lawn) and bushes, shrubs, trees? I want to compare the carbon footprint benefit of lawn versus the same area put into native plantings.
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

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