Why Is the Blooming Time of the Night-Blooming Cereus So Short? An Explanation of the Reasons

Blooming phenomenon. The night-blooming cereus belongs to the cactus family, and it shares a trait with most members of that family: an extremely short blooming time. The night-blooming cereus especially so - a single flower takes only four or five hours from opening to withering, and it always tends to bloom in the middle of the night, which is why it has an odd name in Mexico, called the “twelve o'clock flower”.

Why is the blooming time of the night-blooming cereus so short?

It turns out that the night-blooming cereus has lived for generations in the tropical desert regions of Central America and South America. In the desert, the temperature difference between day and night is very large; daytime temperatures are high and extremely hot, while nighttime temperatures are lower and much cooler. The night-blooming cereus chooses to bloom within four or five hours at night and then withers by the next morning, so that its delicate flowers will not be scorched by the intense sunlight. This special way of blooming enables it to live and reproduce in the harsh, arid and hot environment. Over time, this habit was passed down from generation to generation.

Where does the night-blooming cereus flower bloom?

At first glance, the flower of the night-blooming cereus seems to bloom on the leaves, but in fact it still blooms on the stem. This is because the leaves of the night-blooming cereus have degenerated, and what people see as the so-called “leaves” are actually modified stems. Similar plants such as the cactus, the Christmas cactus (Schlumbergera), and the butcher's broom (Ruscus aculeatus) also appear to have flowers blooming on their leaves, but in fact they all bloom on the stem. Their leaves have likewise degenerated, and the so-called “leaves” are merely modified stems.

When does the night-blooming cereus bloom?

The blooming season of the night-blooming cereus is generally from June to October, and the blooming time is generally after 8 to 9 o'clock at night, mostly around 10 o'clock at night, and the full bloom lasts only 3 to 4 hours, very brief.

When the night-blooming cereus opens, during the first hour of opening, the speed of opening is very fast. The floral tube slowly tilts upward, and the dark purple outer covering slowly opens; then in the following half hour comes the peak blooming period, when the large, snow-white flower made up of more than 20 petals opens, and as it opens both the petals and the stamens tremble, gorgeous and moving. After that comes the regrettable three-stage contraction. The whole contraction process is gentle and orderly, lasting 5 hours, until the flower withers. To admire the wonderful sight of the night-blooming cereus opening naturally, the best time is 20:00--23:00 (that is, 8--11 o'clock at night), 3 hours in total. But only 3 to 4 hours later, the corolla closes and the flower soon withers - truly what is called "a fleeting glimpse of the night-blooming cereus"!

How many times does the night-blooming cereus bloom in a year?

How many times can the night-blooming cereus actually bloom in a year? Relevant records state 4 to 5 times, but the conclusion drawn from flower enthusiasts' many years of potted experience is: it can bloom 6 times a year.

A flower enthusiast conducted a potted night-blooming cereus experiment on a balcony. Over more than 10 years, they potted (including cuttings) 46 pots of night-blooming cereus; last year 20 pots bloomed, with the group blooming 8 times in a year, the total cumulative number of blooming days reaching 26 days, and a total of 151 flowers. Among them, a single plant potted for 10 years bloomed 6 times, with the cumulative number of blooming days reaching 20 days and a cumulative total of 34 flowers.

Why does the night-blooming cereus bloom at night?

1. The night-blooming cereus originated in the Mexican desert of tropical America, where the climate is both dry and hot. Through long-term adaptation to natural conditions, the night-blooming cereus developed the trait of not fearing drought. Its leaves degenerated into very small needle-like forms to reduce water transpiration; daytime temperatures are high and water evaporation is great, so it cannot obtain enough water to open its flowers, and only when nighttime temperatures are lower and evaporation is less can it obtain enough water to bloom.

2. This is related to climatic conditions - only under suitable humidity and temperature will the delicate night-blooming cereus bloom. Summer nights in South America are much cooler than the daytime, and blooming at night allows the flowers to avoid the fierce sun: only at 21:00--22:00, with a temperature of 20--26°C and a relative humidity above 80%, are the conditions for the night-blooming cereus to open present. Late at night, as the temperature drops, the night-blooming cereus gradually shrivels; such a blooming period avoids damage from high and low temperatures.