Why Do Dandelions Close Up at Night?

Widely known and appreciated for their medicinal properties, dandelions belong to the Asteraceae family, meaning that they’re indirectly related to both daisies and sunflowers. And just like daisies, dandelions also close up at night, a behavior that some might consider peculiar for plants. So, why does this happen?

Dandelions close up at night due to a mechanism called nyctinasty. Nyctinasty is an evolutionary trait in which some plants “go to sleep” when it gets dark. The reasons for nyctinasty aren’t fully understood, but it’s commonly linked to the reproductive and self-defense behaviors of these plants. 

In the rest of this article, I’ll tell you more about dandelions and the different theories concerning nyctinasty. I’ll also share some interesting facts about dandelions that might convince you that they’re more than just a weed. Let’s get right into it!

What Makes Dandelions Close Their Petals at Night?

Nyctinasty is a mechanism by which a plant’s petals and/or leaves close up in response to darkness. This is a biological event that is a part of certain plants’ circadian rhythm – proving that plants are more similar to us than we think. Dandelions are therefore considered to be nyctinastic plants (i.e., plants that open up during daytime and close up at night).

Dandelions are not the only flowering plants that exhibit this fascinating pattern. Hibiscuses, poppies, and tulips also present this kind of behavior. Legumes such as beans and peas are also known to close up their leaves at night.

Self-protection and successful reproduction are the most probable explanations for nyctinasty in plants. Nyctinasty is an evolutionary process that aims to improve such plants’ defense mechanisms and increase their chances of pollination, as we will discuss later in this article.

It’s important to keep in mind that nyctinasty is much more than a response to a stimulus. Phototropism, for example, is a phenomenon wherein plants are attracted to a source of light and tend to grow toward it. Nyctinasty, however, is more a behavior than a response, as plants that employ this mechanism open and close every single day. 

Scientific Explanations for Nyctinasty

There are multiple theories as to why dandelions exhibit nyctinasty – and they all provide plausible explanations for this fascinating phenomenon. 

English naturalist Charles Darwin was one of the first to investigate the mysterious behavior of nyctinastic plants. 

According to him, nyctinasty is an evolutionary response developed by some plants in order to protect themselves from cold nighttime temperatures. By closing their leaves and petals, these plants can avoid freezing at night. 

Pollination is also a possible explanation for nyctinasty in plants. Plants use their bright flowers and unique scents to attract pollinators such as insects, birds, and small mammals. 

A second theory, therefore, suggests that because there is less chance of these pollinators visiting at night, nyctinastic plants close up when it gets dark. They then reawaken in the daytime, when these pollinators are more likely to come round.

Nyctinasty in plants is closely linked to their reproductive behavior. By folding their petals and leaves, nyctinastic plants are able to keep their pollen dry and hence, light. 

If a plant’s pollen is light enough, pollinators will find it easier to carry it to other plants, thus maximizing its chances of successful reproduction.

Nyctinasty is also suspected to be a highly advanced defense mechanism. 

To elaborate, a third theory proposes that in order to protect themselves from unwanted nighttime visitors, nyctinastic plants like dandelions close up to create clear space around them. In turn, this clear space makes it easier for nocturnal animals, such as bats and owls, to spot and catch any creatures that might try to feed on the plants at night. Think of it as nyctinastic plants “setting up” their predators as bait.

If this were the case, that would mean that nyctinasty is a much more complex behavior than was previously thought. In view of these considerations, one can understand why dandelions are considered highly evolved plants. 

Another possible explanation for nyctinasty is that some plants employ this mechanism to prevent moonlight from interfering with their ability to tell day from night. 

And if you’re wondering whether plants are capable of measuring day/night cycles, the answer is “yes” – they are. Therefore, dandelions may close up at night to enhance their sensitivity to changes of duration in light/darkness cycles.

Interesting Facts About Dandelions

The name “dandelion” originates from the French phrase “dent de lion,” meaning lion’s tooth. The reason behind the name is that these plants feature deeply toothed leaves, which someone at some point must have compared to a lion’s teeth. 

Their flower heads consist of many tiny individual flowers, all packed together. One thing many people do not know about dandelions is that each petal is actually a flower. 

Dandelions’ bright, showy flowers rest upon hollow stalks that can get quite tall – up to 27.5 inches (70 cm). If we were to remove a dandelion’s flower head or cut into its stem, a milky white substance called latex would come out of the plant. 

Dandelions originated in Eurasia but can now be found pretty much anywhere around the world. It is believed that Europeans took dandelions with them when they migrated to North America, probably to have something that reminded them of their home. 

Being rather resistant and adaptable, dandelions can be spotted in a variety of habitats – especially wide pastures, lawns, and tracks. 

Dandelions also possess a wide range of medicinal properties:

  • They are a powerful diuretic, meaning that they increase the amount of urine produced by the body.
  • Their leaves promote a healthy appetite and facilitate digestion. 
  • Their leaves also have a protective effect on the kidneys, helping them function more effectively.
  • Their flowers are rich in antioxidants. 
  • Historically, dandelions’ roots have been used to detoxify the body. They were also used to treat heartburn and various skin ailments.
  • Their roots also act as a mild laxative.
  • According to some studies, dandelions may help normalize sugar levels, meaning that they could possibly be used to manage diabetes.
  • Evidence even suggests that dandelions could possibly lower cholesterol in humans, although further research into this is required.

Dandelion leaves are perfectly edible and may be added to salads, made into a pesto, or sautéed like any other vegetable. If you are willing to give any of these recipes a try, keep in mind that dandelion leaves taste somewhat bitter. 

Dandelion heads may even be dipped into a batter made of flour, egg, milk, salt, and pepper and deep-fried until golden.

Dandelions Are Widely Misunderstood

Now that you know how special dandelions are, you might be wondering why so many people consider them a weed. In fact, it’s not unusual for gardeners to look for ways to get rid of dandelions. 

A simple online search tells us all we need to know about how dandelions are perceived by most, as there is more information on how to eradicate them than there is on how to care for them. Clearly, not many people are interested in growing dandelions in their gardens, which is a shame considering their many beneficial properties. 

Dandelions are a wonderful source of nutrients, rich in calcium, magnesium, potassium, fiber, and vitamin C, among others. Their young buds even contain a moderate amount of protein. 

Despite their bad reputation, dandelions are actually more nutritious than some fruits and vegetables. If you’re looking for a nutritious edible plant to add to your garden, you should definitely consider dandelions!

Always keep in mind that while perfectly edible, not all dandelions are suitable for human consumption. Stay away from dandelions that have been treated with chemicals, and never harvest herbs that are near a road.   

Being perennial plants, dandelions grow back every year. Dandelions are also remarkably adaptable and easy to care for. They thrive in both favorable and unfavorable conditions, which makes them an ideal crop. 

Unlike many plants that attract aphids, dandelions are resistant to pests such as aphids and mealybugs. They grow quite quickly and do not require special care. It should come as no surprise that this resilient, fast-growing, and pervasive nature has likely contributed to the dandelion’s reputation as a troublesome weed.

Its botanical name, taraxacum officinale, comes from both ancient Greek and Latin, meaning a plant with medicinal properties, as well as a remedy for various disorders. Unlike today, people in the past were quite appreciative of this plant’s remarkable properties.

Conclusion

Nyctinasty is the mechanism that makes dandelions close up in response to darkness, only to then open up again when exposed to sunlight. Other nyctinastic plants include daisies, hibiscuses, poppies, and tulips.

There are several possible explanations as to why these plants close up at night, the most plausible ones being:

  • To protect themselves from lower temperatures.
  • To conserve their energy (and, perhaps, even their odor) for when pollinating insects are most active.
  • To prevent their pollen from getting excessively wet and heavy, thus making it easier for pollinators to carry it.
  • To defend themselves from nocturnal predators.

If you found this guide helpful, I recommend my complete guide on preventing dandelions from spreading. You’ll learn everything you need to know about keeping dandelions under control and getting rid of them for good: How to Prevent Dandelions from Spreading (Complete Guide)

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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