Cactus leaves become needle like, which helps to reduce transpiration.
Many people may wonder if it is the first time to see the immortal. Why does it only grow thorns but not leaves?
Doesn’t it need photosynthesis?
Don’t worry, next we will answer for you one by one.
Why does cactus have thorns?
To know why cactus only grows thorns but not leaves, we have to start from cactus’ hometown.
Cactus is native to South America and Mexico.
Their ancestors faced the harsh arid environment and struggled with the rolling yellow sand, little rain and water shortage, and the changeable climate of cold and hot.
After thousands of years, they finally have a foothold in the desert.
But its posture is different: its leaves are missing, and its stems have become succulent, pulpy and prickly
This change is of great benefit to plants such as cactus.
As we all know, plants drink a lot of water.
Most of the water they drink is consumed by transpiration.
Leaves are the main transpiration part.
Most of the water will run away from here.
According to statistics, for every 100 grams of water absorbed by cactus, about 99 grams run away through transpiration, while only 1 gram remains in the body.
In the arid environment, water is hard won. Where can cactus afford such a huge expenditure?
In order to deal with the cool drought, the leaves of cactus degenerated, and some even became needle or thorn like.
This fundamentally reduces the transpiration surface, thus reducing the loss of water.
How much water-saving capacity does cactus have?
Some people planted apple trees with similar height with cactus and observed the water consumption of them in a day in summer.
As a result, apple trees consume 10-25 kg of water per day, while cactus consumes only 20 g of water.
This difference is thousands of times.
This is not cactus stingy, but the necessity of its survival.
If an apple tree with dense leaves is planted in the desert, it will not survive.
Secondly, cactus has many kinds of thorns.
Some become white fluffy and cover themselves tightly.
They can reflect strong sunlight to reduce body surface temperature.
They can also reduce water transpiration.
On the one hand, cactus minimizes water transpiration, on the other hand, it stores a lot of water.
If we don’t store water, cactus may dry up at any time in the desert where there is little rain.
The stem of cactus becomes succulent and pulpy, and its root also goes deep into the sand, so it can absorb and store a lot of water.
It is difficult to absorb water because it contains a lot of water.
Cactus’ water storage ability is amazing.
Some cactus fleshy stems are as thick as a water tank and more than 10 meters high. They are almost like a water storage bucket.
If a passer-by is thirsty, he can drink a drink from the desert with a knife.
Plants such as cactus adapt to arid climate by these changes in their body shape.
That’s why cactus has long thorns.
How to maintain cactus
Cactus is a succulent plant and is drought resistant. It will not die completely even if it is not watered in January.
But it must be watered to make it grow healthily.
In winter, we water every 20 days or so.
The watering time should be in the afternoon with high temperature.
If the house is relatively dry, we can also spray water on the leaves to keep the stems green.
After the whole plant enters the dormancy period, we don’t need to water it.
In spring, with the rise of temperature, we can appropriately increase the number of watering.
Our principle of watering is not to dry, not to water, but to water thoroughly.
But we can’t water too much, and we can’t stop watering for a long time.
When the temperature rises to about 20 ℃, it is generally advisable to water once every 7-10 days.
High temperature and high evaporation in summer make cactus grow vigorously.
This is also the season with the largest water demand for edible cactus.
We usually need to water cactus every 3-5 days.
When the temperature rises above 30 ℃, we’d better spray water on cactus stems 1-2 times every morning and evening.
This is to maintain the swelling pressure of the stem and increase its ornamental,
In autumn, we should gradually reduce the amount of water.
We should also pay attention to the water temperature and quality when watering potted cactus.
Water should preferably be neutral or slightly pH acidic.
If we use tap water, it’s best to put the tap water for two days before using it.
In addition, when we water, the water temperature should be close to the temperature in the room.
Moreover, we should pay more attention to potted cactus in cold areas in the north.