Daisies are one of the most popular plant options among gardeners. They’re hardy, durable, and above all, simply beautiful. Still, there’s one common question newer gardeners often have after growing some daisies: Why do daisies close at night?
Daisies close their flowers at night to protect their pollen and internals against nocturnal insects, animals, dew, moisture, and weather conditions. This behavior also helps daisies preserve biological resources.
In this article, I will talk more about why daisies close at night and how it benefits them. Keep reading to find out more.
Why Daisy Flowers Close at Night
I should begin by mentioning that although not all plants close at night, this behavior is not uncommon in the floral kingdom. The behavior of closing at night is known as nyctinasty. Daisies are one of the better-known species of plants that exhibit nyctinasty.
It’s helpful to keep in mind here that there probably isn’t one single reason why daisies close up at night. Rather, a multitude of factors have improved their rate of survival over an extended period of time and now warrant the existence of this interesting behavior.
Below are the most well-established reasons why daisies close up at night. We will also look at the evidence behind these reasons.
Closing Flowers Helps Preserve Resources
First and foremost, daisies close up at night to preserve resources. Now, you might be wondering, what kind of resources would a daisy possibly have to preserve?
Put simply, daisies want to preserve the attractant chemicals in their flowers. Daisies must use resources (nutrients) to produce these attractant chemicals, which play a major role in bringing pollinators to the flower. Pollination, of course, carries great priority to all plants, daisies included.
Insects that play a significant role in pollination, such as bees, flies, butterflies, and other critters of the sort, are active mostly during the day.
There are a few important night-time pollinators, with one of the more effective ones being moths. However, these tend to pollinate different kinds of plants, particularly ones that are usually pale and rely much more heavily on scent-based attraction.
Daisies, with their bright and vibrant colors, use both visual and scent-based attractions to attract pollinators.
Because the pollinators that commonly do the job for daisies are only around during the daytime and because daisies can’t effectively attract pollinators during the nighttime, it makes sense for them to close their flowers at night to preserve the previously mentioned attractive chemicals.
Even if we dismiss the preservation of these chemicals as something insignificant (since daisies continuously produce these chemicals naturally and aren’t really in danger of running out as long as they are healthy), it’s still ideal for them to close up during the night.
Daisies won’t attract many pollinators at night even if they remain open, and there are several other benefits to closing up at night.
It Protects Against Nocturnal Insects and Animals
While we did discuss earlier the important role of insects in the pollination of plants, including daisies, not all insects are pollinators. As many gardeners know, insects can be pests that cause serious damage to plants. Many of these damaging insects are nocturnal.
While some insects may not cause physical damage to the plant, they may ‘steal’ pollen or nectar. This means that they may take pollen or nectar without ever causing pollination.
In fact, an insect problem left unattended might be what’s holding your daisies back from achieving their full glory when they bloom.
Small animals that like to forage for food under cover of darkness (think squirrels and rabbits) can also pose a threat to delicate plant life, especially since many of these animals are either herbivores or omnivores.
Daisies close up their flowers to protect themselves against this damage from night-time insects and animals. This protects the colorful internals of their flowers while ensuring that the valuable pollen inside stays hidden and protected.
Now, you might be thinking that flimsy flower petals aren’t possibly a match for the animals interested in consuming the plant. You’d be right—flower petals are thin, weak, and do not provide physical defense against even the smallest of animals.
The protective element lies in the fact that by closing up, daisies hide the colorful and easily identifiable insides of their flower petals, stop releasing their attractive scent into the air, and instead reveal their lower petals.
These lower petals take on a color ideal for making it harder for potential predators to identify them. All these factors combined make it less likely that a predator will spot them.
According to the British Ecological Society, researchers from Stellenbosch University found that tortoises could not tell the lower leaves of daisies apart from a green leaf background, even though tortoises favor protein-rich flowers over leaves.
The researchers found similar results when they showed the colors to other common predators of daisies.
Closed Petals Protect Against Dew and Moisture
Dew is known to have some significant benefits for plants. These benefits are centered around the fact that dew provides plants with a protective layer.
This layer of moisture prevents the plant from losing any water to transpiration until the dew itself has all evaporated. This effectively makes dew an extra water supply.
However, while the dew is great for the flower’s exterior skin, it can be harmful if it gets into the interior. Pollen is supposed to be light—so light that the air can transport it to other plants. Many of the plant species in the world today rely heavily on air transport for pollination.
If pollen gets wet, it becomes heavy. Air transport for wet pollen is out of the question; however, transport via insects, especially smaller ones, becomes more difficult too.
Stagnant moisture is associated with an increased risk of plant disease, more specifically, diseases caused by the growth of fungi. As most gardeners are aware, fungi require moisture to grow.
Flowers Close for Shelter Against Weather Conditions
Daisies don’t only close up at night time—they also close up whenever there’s rain, even if it’s during the day. In fact, daisies are known for their ability to predict rainfall and close up in preparation.
The reasons for daisies not wanting to be exposed to rainfall are similar to the reasons for dew and moisture; however, this applies on a much larger scale.
In addition to the previously mentioned pollination reduction, excessive water exposure can cause nectar dilution. This dilution will make the nectar less appealing to insects; the daisy would have to expend resources on re-concentrating the nectar once the rain passes over.
When rainfall is extreme, or in cases of hail, there is the risk of the daisy enduring some damage to its reproductive organs. In the same sense, daisies closing up at night offers their internals better protection against night-time frost.
How Daisies Close Their Flowers
Have you ever wondered how exactly daisies close up their flowers on demand? I mean, plants can’t usually move on their own, right?
Petal closure is quite an interesting mechanism.
Daisies have lower petals that become exposed when the flowers close up. Low light and temperature (night-time) conditions cause these lower petals to grow faster than the upper flower petals.
As a result, the upper flower petals sort of curl in while the bottom-most petals grow and take up space, resulting in what we see as a closed-up daisy flower.
Nyctinasty is the name given to the plant’s behavior of closing up at night. Daisies’ lower petals grow faster than their upper flower petals when temperature and light are low, which effectively causes their flowers to close.
There is no exact answer for why daisies close up at night, but it is likely due to several factors that aid their long-term survival.
Closing up at night helps daisies preserve important resources, such as attractive and aromatic chemicals. It also protects their internal reproductive organs and valuable pollen against night-time threats, dew, moisture, rainfall, and frost.