The Moonflower, Selenicereus wittii, is a rare and unusual cactus which spirals around tree trunks with leaf-like, flattened stems or pads.
It is found exclusively above the high waterline of the floodplain rainforests of the Amazon Basin. Its white, nocturnal flowers, reach to be 27cm in length and emit a beautiful sweet-smelling fragrance as they blossom at sunset to attract their pollinators – two species of hawkmoth with extremely long proboscises (tongues). Two hours after flowering begins, it changes its scent to something far less attractive and then the flowering is over by sunrise.
Alex Summers, Former CUBG Glasshouse Supervisor, is responsible for growing and nurturing this rare and unusual cactus in the Tropical House at the Botanic Garden. He says:
“I’m so excited to see and share this most unusual flowering. It’s very rare to have this plant in our collection and we believe this is the first time the Moonflower has flowered in the UK.
I noticed the flattened stems, or pads, which swirl around the trunk of our Water Chestnut had sent out a flowerbud in late November – which was a lucky spot as it’s almost 12 feet up in the air and could have so easily been missed! But it has only recently increased radically in size which means a flowering is imminent.”
The Moonflower is an epiphyte, which means it relies on another plant as an anchor point. The stems of this particular cactus do not resemble any ordinary cactus. They are flattened, smooth and leaf-like and create an intricate swirling pattern as they wind their way around their host tree trunk. In the Amazon rainforest, they do this to maintain a position above the seasonal inundation of flood waters from the Amazon and its tributaries. These waterways are important to the dispersal of this cactus as the seeds float, and this allows them to be carried away from the parent plant to find another tree crevice to lodge and grow in.
When it eventually flowers, the process begins by the breaking bud emitting a sweet smelling fragrance (allegedly with the same floral notes as those used in one of the popstar Rihanna’s perfumes according to nature writer and broadcaster Richard Mabey!) just as it begins to open and throughout its flowering, to attract the night flying hawkmoth. Two hours after it has fully opened, its scent changes to a more rancid smell, before closing up for good at sunrise.
Find out more in our Moonflower Factfile.
“I’m so excited to see and share this most unusual flowering. It’s very rare to have this plant in our collection and we believe this is the first time the Moonflower has flowered in the UK.”
Alex continues: “The flower has its nectary right at the base of the floral tube which means it can only be pollinated by an insect with a long tongue or proboscis. This is believed to be only one or two species of hawkmoth. Once it has flowered and hopefully successfully pollinated, it then dies a few hours later, emitting a rancid smell.
I’m so intrigued and excited to experience it flower! We acquired a small pad from Bonn Botanic Garden in 2015. I attached it to our Water Chestnut tree (Pachira aquatica) in our Tropical House and it’s since grown around the tree and now one of the stems has decided to send out a flower bud. We expect it to flower like this most years from now on.
Other than being a highly rare and unusual event to witness, I also love the story about how this elusive flower came to our attention. This is thanks to an intrepid British female environmentalist and Botanical artist Margaret Mee. She first saw the Moonflower in the Amazon in 1972 and then went back in her 70s to paint it in 1988.”
While Alex won’t be producing a botanical painting of this beautiful bloom, he will be capturing it on camera. The team have set up a webcam in the hope they can livestream the flowering to share with other enthusiasts. Updates and information can be found via the Garden’s twitter and facebook feeds – @CUBotanicGarden – or by checking the webcam page via the Garden’s homepage.
Alex is hoping to hand pollinate it with the hope of producing seed. He and his Glasshouse Assistant, Barbara, are on night watch and measuring the stem daily, as catching the flowering is a one-off event they can’t risk missing.
Please note that the Glasshouse Range is currently closed, so the only way you can see this fascinating and intriguing flower is by following us on social media and keeping an eye on the livestream. Flowering is anticipated to happen within the next 2-3 days!
For press enquiries or images contact the Press Office on 01223 762994 or press@botanic.cam.ac.uk
Scroll through these images to explore this amazing and strange plant
