Contact Us Host an Event Volunteer Join

Q. Who is Mr. Smarty Plants?





Ask Mr. Smarty Plants


Search Smarty Plants
See a list of all Smarty Plants questions


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


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


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

Determining male/female wax myrtles
March 06, 2009 - We are planning to use Wax Myrtle as a screen plant, and want to be sure that we are successful in having berries for the birds. We have read that berries are only on the female plants. When we aske...
view the full question and answer

Do plants grow faster in natural or artificial light?
March 13, 2009 - Do you think plants will grow faster in natural light or artificial light or a combination of both? And why do you think that. and need your answer for my biology project please and thank you for your...
view the full question and answer

Phytoremediation Plant List for St. Louis MO
April 19, 2012 - My goal is to transform urban blight plots (some up to 1/4 acre) into viable community gardens having healthy, living soil as their foundation. To this end I am researching phytoremediation (thanks...
view the full question and answer

Plants addicted to caffeine
February 28, 2009 - Im doing a science project on if plants can get addicted to caffeine, but coffee in general and i was wondering what materials you need to figure that out.
view the full question and answer

What does the name montana mean in a species name?
August 21, 2015 - What does the name montana mean in a species name?
view the full question and answer
