The incredibly rare moment an Amazonian cactus blossomed at Cambridge University’s Botanic Garden was caught on camera.

Experts had been closely monitoring the Moonflower and had been posting updates every day ahead of the event which is thought to be a first for the UK.

A night watch was kept throughout the week so they did not miss the flowering of Selenicereus wittii - an event which begins at sunset and is over by sunrise.

Wisbech Standard: The rare Amazonian cactus called the Moonflower at Cambridge University's Botanic Garden blossoms for what botanists believe is the first time in the UK.The rare Amazonian cactus called the Moonflower at Cambridge University's Botanic Garden blossoms for what botanists believe is the first time in the UK. (Image: PA Wire/PA Images)

The Moonflower actually bloomed earlier on Saturday afternoon (February 20) at around 3pm, and the garden said it was 28cm long.

“We have been overwhelmed by the interest in and love for the Moonflower,” said a spokesperson for the botanic gardens.

Wisbech Standard: Glasshouse supervisor Alex Summers rare Amazonian cactus called the Moonflower at Cambridge University's Botanic Garden as it blossoms for what botanists believe is the first time in the UK.Glasshouse supervisor Alex Summers rare Amazonian cactus called the Moonflower at Cambridge University's Botanic Garden as it blossoms for what botanists believe is the first time in the UK. (Image: PA Wire/PA Images)

“Thank you! It's been brilliant having so many people join us for the wait, and then celebrate the opening with us.

“Our director Beverley Glover intends to use samples of the flower's tepals for research after it had been pollinated by our glasshouse supervisor Alex Summers.

Wisbech Standard: A rare Amazonian cactus called the Moonflower at Cambridge University's Botanic Garden as it blossoms for what botanists believe is the first time in the UK.A rare Amazonian cactus called the Moonflower at Cambridge University's Botanic Garden as it blossoms for what botanists believe is the first time in the UK. (Image: PA Wire/PA Images)

“Alex is not sure how successful self-pollination will be as in the wild it’s likely this plant is pollinated with pollen from another flower and self incompatibility is common in epiphytic cacti species.

“However, we were keen to give it a go. Alex took the pollen, using a small paintbrush, and placed it on the stigma and repeated this a number of times in case the stigma matured after pollen release.

Wisbech Standard: Director Beverley Glover with a rare Amazonian cactus called the Moonflower at Cambridge University's Botanic Garden as it blossoms for what botanists believe is the first time in the UK.Director Beverley Glover with a rare Amazonian cactus called the Moonflower at Cambridge University's Botanic Garden as it blossoms for what botanists believe is the first time in the UK. (Image: PA Wire/PA Images)

“As this is the first flowering of Selenicereus wittii in the UK, it was not possible to receive pollen from another flower so self-pollination was our only option.

“We should know within a month if the plant has set seed.”