It’s always fascinating to see a plant with its leaves or flowers wide open and in full bloom during the day. And then, when you see it again at night, it’s all closed up, as if tucked up and ready for bed. Have you ever wondered why this happens?
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The phenomenon of plants that open in the day and close at night is called nyctinasty. It can be compared to our human circadian rhythms. The reasons for this action are not fully understood, but there are many annuals, perennials, vegetables, and various others that have this diurnal cycle.
The reasons why some plants close at night is not fully understood. Researchers, however, have a few theories as to why this happens:
- If the plant reduces its surface area when the sun goes down, it may lead to better temperature retention. Charles Darwin theorized that plants close at night to reduce the risk of freezing.
- The reduction in the surface area reduces night-time herbivory – in other words, herbivores grazing at night will be less likely to graze on a closed plant.
- Another hypothesis relates to herbivores and their predators – that the plant moving its leaves in response to low light will make night-time herbivores more visible to predators. This, in turn, will make the herbivores more susceptible to predators, assisting with the plant’s survival.
- This movement possibly helps capture water by absorbing moisture or catching rain during the day. Then, when the plant closes inwards during the night, the water droplets trickle down to the root system.
There are various theories about why this phenomenon occurs, but without a doubt, it is one of those situations where Mother Nature knows best. You can find nyctinastic plants across the plant spectrum. We have chosen a few examples to look at below. Let’s take a wander through the night garden and find out a bit more about some of the plants that close at night.
1. Various Legumes
There are several plants in the legume family that close up their leaves at night. You will find beans, peas, clover, vetch, alfalfa, and cowpeas in this list.
Each type of legume has its own specific care requirement, but legumes are low maintenance plants for the most part. They generally grow best in bright sunlight and moist soil.
2. Gazania Or African Daisy
A few varieties of the Gazania or African daisy close at night and in cloudy or rainy weather.
Gazanias are hardy plants that flower from early summer all the way through to early fall. Once they’re established in the garden, they’re relatively simple to care for. They are at their best with regular watering, but they are pretty drought resistant. Remember to deadhead the flowers that are finished blossoming for the season.
3. Dandelion Or Taraxacum
Taraxacum or dandelions are invasive weeds native to Eurasia but found all over the world. They can literally take root in barely a pinch of soil. Despite their status as weeds, parts of the dandelion are edible.
They’re quite magical looking, with their pretty yellow flowers and seed heads, sometimes called blowballs or clocks.
Related: Are Dandelions Poisonous?
4. Crocus
The crocus is a perennial native to Asia, North Africa, and parts of Europe. They’re found abundantly in the wild and are usually the first flowers to blossom in late winter or early spring. The crocus’s cup-shaped flowers come in a wide variety of colors and close at night. The crocus is a hardy plant that enjoys regular watering and full sun.
5. Tulip
Tulips are popular spring flowers that come in various colors and shapes. There are approximately 100 species and more than 3000 varieties of cultivated tulips. They also grow wild in Central Asia.
All the other plants on this list are nyctinastic, but tulips are photonastic plants. Their flowers close when there is no light available and reopen when the light returns. They are also heliotropic – this is when a plant moves during the day to find the optimal position to receive light.
Photonasty refers to the opening and closing of flowers in response to changing light conditions. This differs from nyctinastic plants. Nyctinastic plants have an internal rhythm that causes movement. As with nyctinastic plants, this process also appears to conserve energy and warmth to create an attractive environment for pollinating insects.
6. Purple Winecup
With its cup-shaped purple flowers, the purple winecup opens in the morning and closes at night. Interestingly, the blossoms remain closed after the flower is pollinated. Like many of the others we’ve mentioned, this plant loves full sunlight and is hardy and tolerates drought well.
7. Bloodroot
A bloodroot is a flowering plant that grows leaves and flowers on separate stems. The white daisy petals surround yellow centers and close at night. It likes dappled sunlight and moist organic soil.
Traditionally, it was used to make medicine, but it is a skin irritant and should be handled with gloves and care.
8. California Poppy
The gorgeous California poppy has cup-shaped bright yellow and orange flowers. It also rolls up its flowers during the night and when its cloudy. These flowers are at their best in early summer, and like most wildflowers, they don’t require much care. They thrive in rocky and sandy soil.
9. Rose-Of-Sharon
The dazzling-colored flowers produced by the Rose-of-Sharon shrub close up each night. This shrub requires minimal care and reseeds easily. It lives happily in most soil conditions.
10. Magnolia Tree
The evergreen magnolia tree is a sight to behold as it can grow up to 50 feet tall, and it has large, 8-inch-wide flowers. These flowers close at night for a few nights before the flowers die.
Related: Trees Similar to Magnolia
11. The Lotus
This hardy water plant closes its flowers at night. This movement gave rise to the ancient Egyptian myth that the lotus gave birth to the sun. The lotus is entirely edible and is also used in traditional Asian medicine.
12. American White Waterlily
The American white waterlily is another water plant with flowers that close from the afternoon and only open again in the early morning.
