Host an Event Volunteer Join Tickets

Support the plant database you love!

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

Difference between Styrax platanifolius and Styrax patanifolius ssp. texanus
November 18, 2011 - What is the difference between a Styrax platanifolius and a Styrax platanifolius texanus?
view the full question and answer

What does spp. stand for in Paspalum spp? From Arlington, TX.
August 11, 2010 - What does the spp stand for when talking about Paspalum spp?
view the full question and answer

Mycotrophic plants that develop underground for years in Alabama
January 10, 2006 - I recently heard someone say that there was a plant that took seven years to grow. They stated that the seed is in the ground but it begins the growth under ground but does not come to the surface for...
view the full question and answer

Smarty Plants on Science Fair projects
September 13, 2005 - I would like to know what kind of plants can grow in two weeks? Please answer quickly so I can do my Science Fair project.
view the full question and answer

Will lead accumulate in the flower nectar of plants used for phytoremediation
January 16, 2009 - I'm attempting to phytoremediate lead in my garden with mustard and/or sunflowers. I also keep bees. I understand that lead is sequestered in roots and stalks. Would the nectar also be contaminate...
view the full question and answer

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